PX3662A_UNIVAC_1540_MAG_TAPE_UNIT PX3662A UNIVAC 1540 MAG TAPE UNIT
PX3662A_UNIVAC_1540_MAG_TAPE_UNIT PX3662A_UNIVAC_1540_MAG_TAPE_UNIT
User Manual: PX3662A_UNIVAC_1540_MAG_TAPE_UNIT
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{-
SPE~
V
RAI\D
TECHNICAL
DESCRIPTION
UNIVAC
'1540
MAGNETIC
TAPE
UNIT
Table
of
Contents
Title Page
Gener
al Information
Modularity
Specifications and Standards 2
Electronics 2
Maintenance 2
Tape
Unit Characteristics 2
Power and
Coo
ling Requirements 4
Magnetic Tape to Computer Characteris
ti
cs
4
Magnetic
Ta
pe Unit - High-Speed Printer Off-Line
Capa
bility 20
List
of
Tables
Table
Tit
le Page
Word A
ss
embly Time (Microseconds) 9
2 Effects of Various UNIVAC Computers
14
Operating with the UNIVAC 1540 Magne
ti
c Tape
Sub
system
3
Operation
Codes
16
4 Ty
pe
Symbols
aDd
Cod
es 22
"
List
of
Illustrations
Figure Title Page
1 UNIVAC 1
540
Magnetic
Tape
Unit ;v
2 '
TV
AC
1540 Magnetic
Tape
Units and 1
Com
puter Configuration
3 Dimensional Data for 1540 Basic Magnetic
Tape
Unit 3
(Air
-Cooled)
4 Magnetic
Tape
U
ni
t -
Computer
1
nt
erface 5
5
Type
1540 Magnetic
Tape
System (Maximum Configuration) 5
6 Tape Format 6
7 Magnetic
Tape
U
ni
t - Status Word
Format
8
8 ExlemaJ Function Word
Format
11
9 Bi...octal Tape Format
12
10
Octal
Tape
Forma
t
13
11
Magnetic
Tape
Unit -
Tape
F
il
e 19
12
Transmit-Extra Computer Word
Format
20
13 Magnetic Tape - Printer
Int
erface
21
ii
i
............
:l
......
...
~
.......
_
..
,.
.....
...
•
• •
Figure
1.
UNIVAC
1540 Mtlg
fl
etic Tape Unit
iv
GENERAL
INFORMATION
Th
e militarized
UNIVAC~540
Magnetic
Tape
Unit
(sec Figure I) provides a large capacity auxiliary
storage for
co
mputing
S~'Slems
operating under severe
environmental
co
nditions. U
NIVAC
tape system
engineers. through their
cJl:pe
rience in designing ship-
board and
la
nd-based equipment to meet mili tary
system requirements. ha,-e designed
and
built a rug-
ged, reliab
le
and
resjXInsi\'c. medium-speed. digital
data
magnet
ic
tape
SIDr.lge'
unit
to
exacting military
standards. At the
same
lime, this unit incorporates
impro
ve
ments
and
ad,-ances in the state-of-the-art.
Th
e
ru
gged cabinet design
and
packaging of compo-
nents per
mi
t use
of
the magnetic tape unit
in
vans.
ships.
ai
r-transportable helihuts
or
Olher enclosures
of
com p
Ul
er equipment designed 10
"go
where the
action I S .
The UN I
VAC
15'
.\fagnet
ic
Tape
Unit (MTU)
employs a pinch-roller
t)-pe
of tape transport and
may be operated oo-Iine under complete
computer
pro
gram
co
ntrol
as
an
input
out
put storage device or
with a high-speed printer for off-line printing of tape
recorded information.. A flexible format allows re-
cording and reading
of
four moduli (18-, 24-, 30-,
or
36
-bit
compuler
.-urds)
an
d three
de
nsities. and
provides recording
0{
magnetic tapes which
is
com-
patible in all
res~
with industry-accepted tape
s
ys
tems. Either even
or
odd
fr
ame parity may
be
utilized and for
added
reliability. the re
dundant
octal
fo
rmat
is
pro\'ided_ A Read-after-Write featu re
checks each frame for parity immediately after re-
cordin
g.
LongilUdioal
parit~
r
eco
rding and checking
arc automatic. A duplexing capability
is
provided
so that
Iw
O computers communicating with the same
magnetic t
ape
unit rna}
sha
re its facilities under pro-
gram contr
oL
In this wa}.
da
ta
or
programs stored
on one tape are available
to
both computers. Further
savings in the facilities are enhanced by the ability
of the 1540 Magnetic Ta
t>e
Unit to read information
in
either the forward
or
backward mOlion of the tape.
Records of
data
may
be
of
va
riable lengths and are
separated by
~
-inch interre
co
rd
g
ap
s (I RG) unless
otherwise extended by suitable programming. Rec-
ords ma y be lengthened
if
suitable interrecord gaps
were provided
in
previous recordings .
The
UNIVAC
1540 Magnetic
Tape
Unit
is
com-
patible with a
ll
UNIVAC
Military Computers and
may
be
supplied with an 18-, 24-, 30-,
or
36-bit
parallel input/output interf
ace
with either
of
two
sets of signal levels. Compatibility both
in
tape for-
mat and
comp
uter programs with the UN I
VAC
1240
Magnetic T
ape
Un
it
is
provided through a manual
switch selection on the 1540 Basic Unit.
This
feature
gives functional characteristics that are identical with
those of the
UNIVAC
1
240
Magnet
ic
Tape
subsys-
tem and permits the use
of
software packages de-
signed for earlier systems.
MODULARITY
Each UNI
VAC
1540 Magnetic
Tape
Un
it
(
MT
U)
is
des
ig
ned to provide a flexible, yet expandable stor-
age subs
ys
tem
to
meet
va
ried requirements.
The
Basic Un
it
, attached to
any
computer channel,
co
n-
ta ins the interface
and
logic circuitry required for a
minimum system as well as for a maximum con-
figuration. The 1540 Magnetic
Tape
Unit consists of
fr
om one to four individual cabinets each containing
two pinch roller type tape handlers (see Figu re 2).
The 1540
Ba
s
ic
Unit contains two tape handlers with
associated read write electronics and one Magnetic
Tape
Contr
ol (MTC). Each 1540
Add
-
On
Unit con-
tains two tape handlers and associated read/write
electronics. Thus, the
Ma
gnetic T
ape
Control
pro
-
vides the necessary jnterface and
co
ntrol logic for
one
com puler channel and for up
10
eight tape
handler
s.
SPECIFICATIONS
AND
STANDARDS
The
UN l
VAC
1540 Magnetic
Tape
Un
it
was de-
signed to meet military specifications
and
standa
rd
s
in
the foll owing respects:
Te
mperatur
e:
(Centigrade)
Humidity:
Enclosure:
Salt Spray:
MIL-E-I6400
, Class 4 (0"
to
50
° operating, -
6r
to
+
75
" non-operating)
MIL-E-16400
(to 95 per-
cent including condensa-
tion)
MIL-STO-I08
Federal Test Method STO
151, Method 8 11
External Radiation:
MIL-E
-1691O
(I
volt
per
r~
.
o
MINiMUM
CO N
FIGU~4r
I
ON
I~
.
O
MA
XtMUM
CO"lfICUR4110N
CH
....
NNEL
....
INPur
CH
....
NNEl
B
UNIV
AC
CO
MP
UTE
R
Fi
f.!,lIre
2 .
UN
I
VAC
1540 Ma
gllet
ic Tal)e
Ullits
and
Coml)!1ter COlljigllratioll
meter over 14
KC-IOOO
Me)
Shock: MIL-S-901 , Cla
ss
II
(deck
mounted)
Vibration:
Inclination:
MIL
-S
TD
-167, Type I
MIL
-£-16400
Ou
tli
ne
a
nd
dimension
al
data for the 1540 are shown
in Figu re
3.
TECHNICAL
DESCRIPTION
ELECTRONICS
The UNIVAC 1540
is
a completely solid-state ma-
chine. Components are mounted on small, plug-in ,
printed-circuit cards which arc assembled in a mod-
ular form
fo
r compactness. This building block tech-
nique and the
ci
rcuit cards ut
il
ized
in
the 1540
ha
ve
a
fi
c
ld
-pro
ve
n record of
re
li
ability in
UN
IVAC com-
pu
t
ers
and
per
i
phera
l
equipme
nt.
Th
e
modu
l
ar
2
c
ha
ss
is uses wire-wrapped circuitry for improvcd
reliabilit
y.
MAINTENANCE
Solid-slate, plug-in modules, along
with
manual con-
tr
ol
s and register and logic indicator
s.
make main-
tenance of the
UN
IVAC 1540 fast and easy, keeping
repair time to a minimum. Manu
al
controls permit
off-li ne maintenance of o
ne
tape unit during on
-l
ine
operation of other units
in
the syst
em.
The tape
transports and all electronics arc easily accessible
from t
he
fro
nt
of
th
e unit. Preventive maintenance
procedurc
..
and adjustments have been simplified
by
several mechanical and electrical improvement
s.
TAPE
UNIT
CHARACTERISTICS
Tape
Width-Y.! inch
Typc-"A"
wound (oxide coating on
in
s
id
e of
tape)
Length-3600
fect maximum
Reels- l
OY.!
inch, compatible hub type
Tape
Ma
rkers- Load Point a
nd
E
nd
of Tape
reflection markers
Method of Tape Moveme
nt
- Tension Arm a
nd
Pinch Rollers
Reading
Method
s-
Fo
rw<l'fd
or
Backward
(high, medium, or low bias)
Tape Supply Detect
ors-Mechanical
Tape
Speed
Read/ Write
R
ewi
nd
Star
t/Sto
p Time
Recording
Techniques
1
20
i
ps
2
40
ips
3/
1.5
ms
Nonreturn to Zero (change-on-one)
$even tracks-
Six
data bit
s,
one parity
bi
t
Densit
y-200,
555.5, or
800
frames per inch
(Program Controlled)
Interrecord
Gap-
¥.!
inch
Extended Interrecord
Gap-3
Y.!
inches
Record Length-Variable
Pa
ri
ty-Lateral
and Longitudinal
Tape Mark- End of F
ile
(Program Controlled)
Write L
ockout-Standa
rd Type, upper reel
U
··
I
~
=
I
.~
I I
'.
,
24
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;:
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49.32l l \
....
~
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22.32 DO TOP VIEW
DO
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ENTRANCE
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ROOM
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BOTTOM
VIEW
DECK MTG. HOLES
36.1
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Fi
g
ur
e
.3.
Dimensio
nfll
Data for 1540
Ba
sic
Ma
g
ne
tic
Tape Unit (Air-Cooled)
3
AIR
EXHAUST
Transfer
Rate
Characters per second -
High Density
Characters per seeond -
Medium Density
Characters per second -
Low Density
96,000
66,700
24,000
Format
(Program
Controlled)
Moduli
-3.
4,
5, or 6
Frame
Charac
l
e
r
~
Biocta
l
or
Redundant Octal
Parit
y-Odd
or Even
Tape
Compatibility
Transport
to
transport
Other
compatible systems
POWER
&
COOLING
REQUIREMENTS
Power
-
Air
Cooled
Units
115V i
10%
1 Pho
se
60
CPS
±
5%
115V:t
5%
3
Phose
400
CPS
±
5%
Air Supply -
70·
F
Power -
Water
Cooled Units
115V±10% 1
Ph
ose
60
CPS
±
5%
115V ±
5%
3 Phose 400 C
PS
±
5%
Water
Supply -
70·
F
B05ic
Add-On
Un
it Unit
1.8
kyo
1.7
he
0.6
kyo
0.1
kvo
600dm
4
00dm
1.6
kvo
1.6 kyo
1.0 kyo 0.4 kyo
.4
gol/
.4
go
l/
mlo min
MAGNETIC
TAPE
TO
COMPUTER
CHARACTERISTICS
Performance
of
Function
A UN I
VAC
1
540
Magnetic
Tape
Unit communi-
cates with the computer
in
the Request-Acknowledge
mode (see Figure 4).
The
computer
issues
comma
nds
to
the Magnetic
Tape
Unit by means
of
the External
Func
ti
on signal and Function Words. Computers
with an 18-bit word structure (e.g., the
UNIVAC
12 18 and 1219) can use the 1540
Tape
Unit as well
as
co
mputers with longer
wo
rd lengths. When the
Magnetic
Tape
Co
ntr
ol
i
n~pe
cts
the function word
4
it selects
th
e spec
ifi
ed
tape transport and performs
the specified operation. Each
Tape
Tran
sport Cab-
inet contains a l6-position Address Switch
fo
r each
tape transport so that each can
be
assigned a logical
number
(1
through 16). UNI
VAC
1
540
programs
use positions I though 8 only.
The
additional posi-
ti
ons
(9 through 16) are used to provide compat-
ibility with
UNIVAC
1
240
programs.
The
address
selection bits of the Instruction Word arc interpreted
by the Magnetic Tape Control according to
the
physical position
of
these sw
it
ches.
No
two trans-
ports may be assign
ed
the same logical number (i.e.,
to
allow identical function on both units).
If
dupli-
cation does exist, prior
it
y is a
ll
ocated to the transport
at the most remote position to the left of the basic
unit (the top transport having
pr
io
ri
ty over
the
bot-
tom unit) regressing toward the basic unit; then
those connected
to
the
ri
gh
t side beginning at the
r
emote
positio
n.
The
operator
must determine
the
logical addresses required by each program and set
the switches accordingl
y.
(See Figure 5 for order
of
priority
.)
The
Instruction Word contains
th
e cooe for one of
six
basic
operat
ion
s -
Duplex
Selec
t
ion,
Read,
Search, Write, Space File, and Rewind
-o
r a com-
bination of two basic operation
s.
To
accept an
External Function Command, the MTU must be in
the
READY
state (Le., operable but not
per
forming
a spec
ific
operation).
The
completion
of
an operation
or a Master Clear places the
MTU
in
the
READY
state.
The
general sequence
or
events for on-
li
ne
ope
ration
with a computer (the Magnetic
Tape
Control in
Automatic mode and in the
READY
state)
is
as
foliows:
• Computer issues an [nst
ru
ction Word via the
Extcrnal
Fun
ction conunand;
• Magnetic
Tape
Control s
amp
les the Instruc-
tion Word and becomes BUSY;
• Magnetic
Tape
Control selects the addressed
tape transport;
• Operations stated in the Instruction Word are
initiated and
ca
rr
ied to
comp
letion;
• Magnetic Tape Control sets a Status Word
on
the input lines as described in subsequent
paragraphs;
r----
-
--
-
--,
EXTERNAl
fUNCtiON
OUTPUT
!lEaUES!
18
TO
36
OUTPUT
LIN
ES
[xtEI!NAL
INTEI!I!UPT
'~PUI
DATA
I!EaUEST
'NPUT
ACKNOWLEDGE
18
TO
36
INPUT
LIN
ES
n 6
n7
I
I
I
I
I
I
I
I
I
I
I
L
___
__
____
~
Figure 4.
Ma
gnetic Tape Unil -Computer Interface
IIASiC
MAGNETIC
TAP
E
UNIT
ADD
-
ON
UN
IT
ORDER
.
OF
PRIOI!IlV
""""""""""
ADD-ON
BASIC
M
~
GNETIC
UNIT
TAPE
UNIT
1 3
2 4
'2
TAPE
2
TAPE
MAGNEIIC
HANDLERS
HANDLERS
TAPE
CONTI!OL
"" ""
.
ADD·ON ADD.()N
UNlT
UNIl
7 5
8 6
2
TAPE
'2
TAPE
HANDlERS
HANDLERS
Figure 5.
Typ
e 1540 Magnetic
TOI
le System (Maximum
Co
n
fi
gu
ra
t
io
n)
5
• Magnetic Tape Contr
ol
interrupts the Com-
puter with External Interrupt Signal after
completion of the operation;
• Magnetic
Tap
e Control i
ss
ues
STOP
com-
mand to transport:
• Computer sample Status Word and acknowl-
edges Interrupt whereby the Magnetic
Tape
Unit becomes IDLE.
(The latter two events may be interchanged, or may
take place simulta
ne
ously.)
Status
Wo
rds and Input Data are transferred on the
Input Lines with identify
in
g signals on the External
Interrupt
Li
ne a
nd
the Input Request Line,
re
spec-
ti
vely. The computer acknowledges receipt of these
transfers
via
the Input Acknowledge Line.
Function Words and Output Data are transferred on
the Output Lines with identifying signals on the
External Function Line and the Output Acknowledge
Lines, respectively. The Output Request Line no
ti
-
fie
s the computer of the MTU ability to accept
Output Data.
Duplexing
Either of two
COmpu
ters
wit
h compatible interface
can exercise contr
ol
over the MTU when the duplex-
END
OF
JAPE
MARKER
3/ 16
'.
I'on
NON
·
OXID
E
SIDE
Of
JAPE
Z "
LONGI!UDINAl
PARITY
P "
LAIERAL
PARITY
X -
DAlA81!
INT
ER
RE
CO
RD
GG
~
':
'
_
"
'CO
ROI,"
3/
4' -
DAIA
NORMAL
(311'1'
EXTENDED)
TAPE
MARK
FORWARD DIRECTION OXIDE
DOWN
TA
PE
MARK
in
g capability is utilized, The following duplex con-
trol functions are provided
via
the
In
struction Word:
• Demand Duplex Contr
ol
(Master Clear)
• Request Duplex Control
• Release
Du
pl
ex
Control
To complete the communication, the Status Word
with Interrupt provides Duplex Comrol status to the
computers as follows:
• Not
in
Duplex Contr
ol
• In Duplex Contr
ol
Through these messages, each computer has contr
ol
of the switchi
ng
funct ions of the duplcxer and each
is
informed of the operational stat
us
of the MTU's
it
shared with the other.
Tape
Markers
The
L
oad
Point and
End
of
Tape
marker
s
are
adhesive-coated strips of aluminum one
in
ch by 3/ 16
inch. placed on
th
e base (uncoated) side of the tape
with the one· inch dimcnsion
paraJ1el
to the tape
ed
ge
. (
See
Figurc 6
fo
r Tape Format.) The Load
Point marker
is
placed 1/ 32
in
ch from track
"0"
or
outside edge of the tape and at least ten feet from the
beginning of the tape. The End of Tape marker is
LO
AD
POINt
MARKER
3/
16'.
I'
ON
NON
·
OXIDE S
ID
E
OF
tAPE
10'
MIN
_
Figure 6. Tape Format
6
placed 1/ 32 inch from track "6"
or
inside
of
the
tape
and at least
14
feet from the end
of
the tape.
The
markers are detected by reflective photoelectric
sensors.
Status
Word
and
Interrupt
(Status
Interrupt
)
The
computer program
is
interrupted after comple-
tion of every operation performed by the Magnetic
Tape ControL except Master Clear and Transport
Address
Selection.
The
Magn.:-tic
Tape
Control
places a Status W
ord
on
th.:-
channel input lines and
a signal on the channel External Interrupt line.
The
bit structure of
th
e Status Word (see Figure 7) en-
ables the computer program
to
determine the slatt:.s
of the
MT
U and whether
or
not the requested oper-
ation was completed successfu
ll
y.
Errors encoun-
tered during a requested operation,
as
well as the
physical status of the Magnetic
Tape
Unit. are indi-
cated in the Status Word. The term "Sta
tu
s Inter-
rupC·
is
used to exprcss this ph ilosophy since the
computer program is interrupted and the status
of
the MTU and the encountere.d errors are designated
in
the Status Word. Any such Interrupt sent to the
computer
mu
st
be
acknowledged
by
the computer
before another External Function with an Instruction
Word will
be
recognized by the Magnet
ic
Tap
e Con-
trol. Success
ful
completion of an operation
wil!
con-
tain n
o·
err
or
indications.
but
other indications of
tape status may be present.
The
Status Word requires a word of at least
15
bits.
If
the computer accepts
wo
rds larger than
IS
bits,
the information in the next higher
order
bits, be-
ginning at bit
ISis
not interpreted.
The
following
paragraphs present the detailed explanation of each
bit
of
the Status Word.
Improper
Condition
(Bit
14=1)
An Improper Condition will occur whenever:
• Selected tape transport
is
not in automatic
condition. A tape transport not in automatic
condition implies one of the
foll
owi
ng
si
t-
uations:
Tap
e
tran~port
was
manually
remo
ved
from automatic.
Tape
transport not
in
ready condition for
one of the fo!iowing reasons:
Power off
7
Tape brokcn
Lamp burnout
Tape load was not accomp
li
shed whcn
tape was mounted.
(This situation also causes the
Tra
nsport
Read
y
Bil
in the
Stat
us Wo rd
to
be
cleared.)
•
No
tape
transport
is
selected when one is
required.
• A forward command is se
nt
to a lape
tra
n
s~
pon
whose tape
is
positioned at End
of
Tape.
• A
re\"efSC
command.
other
than a Rewind
Operation.
is
sent to a
tape
transport whose
tape is positioned at Load Point.
• A
WRITE
instruction
is
issued to a tape
transport that has NO Write Enablc. (This
situation also causes the No
Wr
ite Enable bit
in the Status Word to be set.)
Wh
en
th
e com-
puter has been notified
of
an I mproper Con-
dition. the computer program may then re-
frain from issuing further External Function
commands
to
the tape system to allow
vis
ual
inspection of the trouble and
operator
inter-
vention
to
O\
-ercome the difficulty. or
it
may
issue another External Function command.
An
incoming External Function command to
the tape system clears the Improper Condition
indication.
Duplex
Control
(Bit
13;
0=
In
Control.
1=Not
In
Control)
•
Th
e status
of
the duplexer is indicated by bit 13
of
the
Status Word and is sent to one of the two
computers depending on the action initiated.
•
The
condition '
at
In Control (bit
13
= I) is se
nt
to
the issuing computer when a word is transmitted
by that computer while the duplexcr
is
not in the
proper position.
•
The
condition Not In Control (bit
13
= I)
is
sent
to the non issuing computer when that computer
loses control
as
a result of a Demand Duplex Con-
tra! issued by the other computer.
•
The
condition In Control (bit
13
= 0)
is
sent to
the issuing computer when a Request Duplex Con-
trol
is
issued and the duplexcr is transferred to the
control
of
that compute
r.
.
COMPUTEI1 INPUT
WOAD
-
--
-------------,-11
I "' IMPROPE
I1
CONDITION
_
__
-'
I
"NO
} -
DUPLEX
COWI10l
-----'
0-
YES
I -
IRANSPO~T
I1EADY
--
--
-----'
I
-X
I
RG
DETECTED
------------
I
-OU
T
PU
T
IIMI,..G
ER~OR
-------------'
I - INPUT
liMING
EAI10N
--
-----
----
--
-'
I
-INCORI1E"
FRAME COUNT -
----------
__
-'
I _
lAIEI1Al
PAl1l1Y
ERROR
-------------
___
_
I
-LONG
ITUDINAL PARIIY ER
AOR
----------
____
_ _
-'
I-BACKWARD
}
-
LAST
MOIION
OF JA
PE
--------------
-
o
..
FORWAI1D
I
-JAPE
MARK l
END
OF
FIlEI
----
______
___________
--'
I
-NO
WilliE
ENABLE
--------
___________
_
______
~
I
-END
OF TAPE
-----
---
- -
------------
_
__
_
___
-'
I
-LOW
T
AP
E
------------------------
_ _
______
___
I - l
OAD
PO
INT
--------
________
_________________
---'
Fi
gure
7.
A"agnetic Tape Unit -Status Wore! Format
Transport
Ready
(Bit
12=1)
The
Transpon Ready bit indicates that the last-
addressed tape Iransport
is
in
a ready condilion as
follows:
• Power is on
• Magnetic tape rcel is mounted a
nd
tape
is
properly loaded
• Tape marker detector lamp IS operat
in
g.
8
XIRG
Detected
(Bit
11=1)
The XIRG Detected bit indicates thai an Exte
nd
ed
Interrecord
Gap
(3
i)i
in
ches between records) h
as
been sensed during tape read.
Ta
pe movement con-
tinues until the next record is read.
Output
Timing
Error
(Bit
10=1)
If
the computer
is
sued a Write Instruction to the
Magnetic Tape
Co
ntrol and did not transfer
th
e
fir
st
output
da
ta word, or transferred a requested data
word t
oo
late to be written in
it
s
pr
oper place and
before the Interrupt
is
sent to th
e-
co
mput
er fo
ll
ow
in
g
End of Record. an Output Timing
Err
or occurs.
Thi
s
word transfer time is related to Format and Density
as shown
in
T
ab
le
1.
An
Output
Tim
ing
Er
ror can
occ
ur
during search or
selecti\c
read opera
ti
ons if
the Magne
ti
c T ape
Cont
rol does n
Oi
rece
iv
e a Search
Key
or
S
el
e
cti\e
Re
ad
Code
before assembl
in
g the
fir
st word. T he time requirement may
be
as short
as 2
Y.!
mi
lliseconds from the time the Instruction
W
ord
is received b) the Magnet
ic
Tape Control un
til
the Search K
e).
Selectiw
Read Code. or the
fi
rst
data word mu
st
be
received.
Input
Tim i
ng
Erro
r
(Bit
09
= 1)
If
the computer
bsued
a Read Instruction and
fai
led
to accept a word placed on the input
cab
le by the
Magnetic T
ape
Control before the next word was to
be
placed on the input cable. an Input Timi ng
Error
occurs.
Th
is
error
indicates thai the
compute
r losl
one or more words
of
the
13s
1 rec
or
d since
data
tran
s-
mi
ssion to the
compute
r ceases
fo
r the remainder
of
TAB LE
1.
WORD
AS
SE
M B
LY
TI
ME
(
Mi
c:
ro$e<:ol1ds)
FOJl:MAT
MODULUS
CHAUCTER
200 fpi 556 fpi 800 fpi-
3 8
10
etol
125
45 3
1.2
, Bloct
al
167
60
41.6
5
Bloct
ol 208
75
52.0
6
Bi
oc:
tol
25
0 90 62.4
3
Oc
tol
250
90
62.4
,
Od
ol 334
12
0 83.2
5 Octal
416
IS
O 104.0
6
Oc
to
l 500 180 124.8
O
Rd
er to individual c
omput
er technical description
brochures for inte
rf
ace c
omp
otibility de
fi
nitio n.
9
the record.
Th
e
t<1PC
continues to move to the End
of Record
<1
t which
ti
me the Magnetic T3pc
Co
ntrol
se
nd
s the
St
atus Word
in
dicat
in
g.
the
error
wi
th an
Inte
rr
up
t to the
co
mput
er
.
In
c
orrect
Frame
Count
(Bit
08=1)
An
impr
ope
r modulus spec
ifie
d or so me
fr
ames lost
C3USC-<;
an Incorrect
Fram
e Coum
Error
. T his may
be
caused
by
one
or more of the followi n
g:
•
Th
ere
were not enough frames
in
the record
to complete 3n imegral number
of
computer
words:
•
One
or
mo
r
l.'
chm acters were not prope
rl
y
read
or
r
eco
rded:
• Bad
~IX"ItS
on the tape
cn
used characters to
be
lost:
• R
eading
the r
eco
rd with the wrong
Fo
r
mn
t
(f
or eX3mple. Re3ding Mod 4 with a tape
record in
~I
od
51.
Longitudinal Paril) Error can
be
expected with
I
n
~
correct
Frame
COUnt
E
rr
or
except du r
in
g reading
w
it
h the v.rong modulus.
Lat er
al
P
ari
t y
Error
(
Bit
07=1)
During a writing process. 3 pa
ri
ty
bi
t is a
dd
ed to
each s
ix
-bit character according to a format specified
and th e seven bits are recorded as one frame.
If
th
e
M3gnet
ic
T
ape
Con
trol
de
tects 3 fra me whose Lat-
era l Pa
ri
ty does not 3gree
wi
th that speci
fie
d by the
F
orm
at. du ring
an)
r
ead
t) pc
ope
ra
ti
on or
dur
ing
the po
st·write
check
of
t
he
record
in
g opera
ti
o
n.
a
Lat
era
l Parity
Erro
r occ
ur
s.
Long
i
tudin
al Parit y
Error
(Bit06=1
)
Dur
ing a writi ng process a long
it
udinal even parity
bi
t is generated by the Magnetic Tape
Co
ntrol for
each tape channel
and
recor
de
d after the last f
rame
of t
he
record.
If
the Magnetic Tape
Co
ntrol detects
an error in this par
ity
dur
in
g any read ty
pe
oper
-
a
ti
on or
du
ring the post-write check of the recording
operation. a Longitudinal Parity Error
oc
c
ur
s.
If
a
Frame
Cou
nt Error ever occurs. the
Lo
ngitudinal
Pa
ri
ty Error usua
ll
y occurs. Both would
be
indicated
in the Status Word.
Last
Tape
Mot
i
on
(Bit
05 ;
1 =
Ba
c
kward
. O=
Forward)
An}
' Status Word with imcrrupl sent to the com-
puter
at
the completion of an operation
wi
ll
indicate
the direction
of
the last lape mo
ti
o
n.
The
program
can
determine whether the tape
is
positioned at
th
e
beginning
or
end
of
the record.
Tape
Mark
(Bit
04=1)
A recorded Tape Mark (refer to Write
Ta
pe Mark)
separates Files of information on the tape. Any
Read, Space File, Search File or B
ac
k Read oper-
ation that is limited
to
a File and the post-write
check of the Write
Tape
Mark operation,
will
indi-
cate a Tape Mark in the Status Word.
No
Write
Enable
(Bit
03=1)
When a Write opera
ti
on
is
attempted on a selected
transport that has its Write Enable clear
ed
or the
Write
Ena
ble Ring
is
not inserted in
the
tape reel,
the
No
Write
Enab
le
is
indicated in the Status Word.
End
of
Tape
(Bit
02=1)
When the End of Tape reflective marker is sensed
by the
MTU,
a Ih second
'
'Time-Out'
~
begins after
which no forward movement of
tape
is
possibl
e.
Reverse direc
ti
on tape motion past the tape marker
is
possible.
The
End of
Tape
indication will app
ear
in the Stat
us
Word.
If
forward tape m
ot
ion
is
reiniti-
ated, the marker is sensed agai n and after the
'h
sec-
ond
"Time-O
ut" the
fo
rward
tap
e motion is stopped.
Low
Tape
(Bit
01
=
1)
A tape supply detector has sensed le
ss
than 1
00
feet
of
tape remaining on the selected transport ree
l.
The
Magnetic
Tape
Co
ntrol w
ill
indicate a Low Tape
any time a Status Word is sent
to
the computer with
the tape positioned within 100 feet of End of Tape.
Load
Point
(Bit
00
=
1)
Recording on a
tape
begins at Load Poi
nt
(a reflec-
ti
ve
tape marker placed at least tcn fee t
fr
om
the
ph
ys
ical beginning of
th
e tape).
Th
e Write-Load
Point delay allows for a gap of at least Ih -inch be-
10
yond the L
oad
Point marker (in the forward d
ir
ec-
lion) before the first record may be written. The
Magnetic Tape Control will indicate L
oad
Point in
the Status Word whenever an operation requesting
backward motion
of
tape
is
anempted
wi
th the
selected tape positioned at Load Point.
EXTERNAL
FUNCTION
COMMANDS
Master
Clear
Ope
rations and tape selections are requested by
Function Words being sent to the
MTU
with an
External Function from the computer. A Master
Clear
of the MT U is perrormed when a Demand
Duplex Control
Comma
nd is sensed by the Mag-
netic
Tape
Contro
l.
It
differs from the o
th
er oper-
ations in these three respects:
•
It
may be perf
or
med
at
any time, even when
MTU
is BUSY;
•
It
has priority over a
ll
other opera
ti
ons
in
the Instruction Word; (see Figure 8)
•
It
does not result in a Status Interrupt to the
issuing computer.
The
Mast
er
Clear stops all tape motion (except a
rewinding tape) and sets the
MTU
in the
READY
state. At any time after a Master Clear, the Mag-
netic
Tape
Co
ntrol will accept another External
Function. Since this
fu
nc
ti
on
is
not considered a
normal operation, its use should
be
restricted to
times when the
MTU
is
believed
to
be in an i
ll
ogical
state or when
it
s state cannot
be
determined. The
Mast
er
Cl
ea
r does not clear
the
Write Enable which
is
set manua
ll
y.
To clear the Write Enable, a form
of
"Clea
r Write
Enab
l
e"
in
struction must
be
used.
In
s
truction
Word
Individual operations are performed by the
MTU
under direction of an
Tn
slruc
ti
on Word. When the
computer
out
put word
is
transmitted
wi
th an Exter-
nal Function signal,
it
is
sensed at the Magnetic
Tape
Control as a command. The operation to
be
per-
formed, format and density,
if
required, and
th
e
transport selection address
or
reading bias are de-
fined in the Instruc
ti
on Word.
The
format for the
Instruction Word is shown in Figure 8. The ind
i-
·
'ndi
co
t
e.
po.ition
01
oddre"
,wi
tch
on
each
tope
t.on.port.
Allowonce i.
made
lor
16
tope
t.on.porl>
to
relain
p.ogram
compotibility
with UNIVAC
12.0
Ma
gne
tic
Tape
Sub.y.t
e m.
P
.og
ram
.
w.illen
fa.
II.'
on
the UNIVAC
1.540
Magnelic
Yope
Sllb,y.tem
add
....
only '
ape
t.
on.port
po.ition.
1 t
hrough
8.
• = u
ro
or
one.
Figure 8. External FUllction W
ord
Formnt
vidual
tape
transport is selected by bits
05-00
of the
Instruc
ti
on Word.
MTU
consists
of
a maximum of
eig
ht
tape
transports each of which must be assigned
a logical number by
th
e oper
ato
r on the transport
selection switch provided for eaeh tape handler.
Format
(Bits
10
-
7)
The
Format
pan
ion
of
th
e Instruction Word
co
ntains
Modulus,
Character
, and Parity designators. A
com·
plete F
or
mat selection must
be
included in all I
n-
st
ru
ction Words w
hi
ch
request a reading
or
recording
operation with the exception that Modulus may
be
ignored in
th
e Write
Tape
Mark Instruction.
The
Modulus designator and the Character designat
or
direct the Magnetic
Tap
e Contra)
in
the assembly
and disassembly
of
computer words from or
to
tape
frames.
11
Character Designator (Bit 8), 1 Selects Octal; 0
Selects Bi-octal
Bi-octal
or
octal (redundant) format
is
specified
in
operations requiring reading
or
writing.
The
bi·octal
format disassembles 18-, 24-, 30-,
or
36-bit
com·
puter words into 3, 4, 5,
or
6 s
ix
-bit-plus-parity tape
frames, respectively, during recording (vice versa for
reading). (See Figure 9.)
The
octal
fo
rmat dis
as·
scmbles 18-,
24-
, 30-, or 36-bit
comp
uter words into
6,
8,
10
, or
12
tape frames, respectively, during
recording (vice versa for read
in
g).
Tape
Channels
3, 4, and 5 contain
th
e sa
me
information
as
Chan-
nels 0, 1, and 2, respeclively, in each fra
me
. e.xcept
when Channels 0, I, and 2 contain zeros,
Cha
nnels
3, 4, and 5 contain ones.
Odd
parity is selected by
the Magnetic
Tape
Control when writing or reading
Octal Characters. The redundant recording in octal
•
1'0
....
...
0 '.aPE
o
ECTo()f<.;
OXIDE
THIS EDGE }
OF TAPE
NEx r
TO
TR
AN
SPO Rt
SIDE
OXIOE
SI
DE
OXIDE
SIDE
OKIDe
SIDE
• , •
• , •
· , •
3 2 0
MODULUS 3
MODULUS "
3 2 0
MODULUS
~
3 2 o
MODULUS 6
3
11
0 FIIAME
2ND
FIIAME
'"
FRAME
tAPE
CHA.NNEl
4TH FRAME
311
0 FRAME
2N D FRAM E
'" FRAME
StH FRAME
4
TH
F
RA
ME
3RO
FRAME
2ND
FRAME
1
ST
FRAME
TAPE
CH
A.N
N
El
6TH FRAME
~TH
FRAM E
4TH
FRAME
3RD FRAME
2ND
FR
AME
1
ST
FR
AME
TA
PE
CH
AN
NEl
Fi
g
ur
e 9.
Hi·
oc
tal Tape Format
format adds to the reliability (see Figure
[0
).
F
or
compatible tapes, data
mu
st be recorded
in
Bi
-octal
format.
The Modulus Specifies tile
Length
of
the ComlJtder
Word
To
Be
Hecorded
011
ra
pe
or
Read
fr
olll
tire
rape
(Refer to rable 2)
Modllills 3 (designator bits
10
and
09
= 00) -An
18-bit computer word is disassembled and recorded
as three tape frames of
Bi
-octal Character format or
six
tape frames of Octal Character format.
If
a com-
puter delivers a word larger than
18
bits for record-
ing, the Magnetic Ttlpe Control
will
record the lower
o
rd
er
18
bi
ts
of the word on the tape and discard the
remaining
high
order b
it
s.
During Mod 3 reading
12
operat
ion
s, three tape frames are assembled as an
18-bit computer word for
Bi
-octal Character forma
t,
or six tape frames are assembled as an IS-b
it
com-
puter word
in
Octal Character format.
If
the com-
puter word size
is
larger than [8
bi
t
s,
the frames are
assembled
in
the lower order 18 bits and zeros are
placed
in
remaini
ng
hi
gh
order bi
ts
(see Figures 9
and
10
).
Modll/us 4 (designator bits 10 and 09 = 01) - A
24-bit computer word
is
disassembled and recorded
as four tape
fr
a
me
s of Bi-oct
al
Character format or
eight tape frames of Octal Character format. If a
computer delivers a word lar
ge
r than 24
bi
ts for
recording, the
Ma
gnet
ic
Tape
Control
wi
ll
record
the lower ord
er
24 bits of the word on the tape and
discard the remaining high order bits. During Mod
fORWARD
TAPE
DI
RE
CTION
'"
FRAME
51'
FRAME
OXIDE
'"
fRAME
SIDE
"0
FRAME
2ND
FRAME
1ST
FR
AME
, , • 3 , 0
TAPE
CHANNel
MODULUS 3
'"
FRAME
'"
FRAME
'"
FR
AM E
51'
FRAME
OXIDE
'"
FRAME
SIDE
"0
FRAME
2ND
FRAME
'" FRAME
, , • 3 , 0
TAPE
CHANNEL
MODULUS 4
}
10TH
FRAME
THIS
EDGE
'"
FRAME
Of
lAPE
'"
FRAME
NEXT
TO
'"
fRAME
TRANSPORT
FRA
ME
'"
51'
fRAME
'"
fRAME
OXIDE 3RD
fR
AME
SIDE
2ND
FRAME
IS'
FRA
ME
, , • 3 , 0
TAPE
CHA
NNEl
MODULUS S
FORWARD
TAPE
DIR
ECTION
12TH
FRAME
11TH
FR
AME
10TH
FR
AME
'"
FRAME
'"
FRAME
""
FRAME
OXIDE
'"
FRAME
SIDE
51'
FRAME
'"
FRAME
"0
FRAME
2ND
FRAME
I
ST
FRAME
, , • 3 , 0
TAPE
CHANNEl
MODULUS
(0
Fig
ur
e
10
. Octal T
ape
Format
13
TABLE
2.
EFFECTS
Of
VARIOUS
UNIVAC
COMPUTERS
OPERATING
WITH
THE
UN-IVAC
1540
MAGNETIC
TAPE
SUBSYSTEM
MOD
3
BCD
WRITE
UNIVAC
121S
For
eoch
IS-bit
word
and
1219
received,
the
1540
Single
Chonnel
writes 3
fromes
(On
e IS-Bit
on
the
tope.
Mod 3
is
Word
Is
recommended
for
Output
/Request single
chonnel
operation.
UN
I
VAC
121S
For
each
36-bit
word
and
1219
received,
the
1540
Duol
Chonnel
writes 3
frames
(One
36-Sil
on
the
tope.
Since
only
Word
Is
the
IS
lSB
ore
written
Output
/Request
Ihe
'8
MSB
are
"Iosl."
U
NI
VAC
1206,
For
each
30-bit
word
1212,
CP-642B,
received,
the
1540
or
1230
(One
writ
es
3
fromes
30·Bit
Word
is
on
the
tope.
Since only
Output
/Request) the
18
l
SB
are
written
the
12
MSB
ore
"los
t."
l
SB
-
le
ast
Significant
Bits
MSB-
Masl Significont
Bits
MOD
4
BCD
WRITE
For
eoch
IS-bi
t
word
received,
the 1
540
writes 4 fromes
on
the
tope:
1
frome
of
zeros
followed by
3
doto
fromes.
for
eoch
36·bit
word
received,
the
1540
writes 4 fromes
on
the
tope.
Since
only
the
24
Sl S
are
written
the
12
MSB
are
"
1051.
"
For
eac
h 3D-bit
word
received,
the
1540
writes 4 fromes
on
the
tope.
Since only
the
24
l
SS
ore
written
the
6
MSB
are
"1
051.
"
MOO
5
MOD
6
BCD
WRITE
BCD
WRITE
F
or
eoch
18-b
it
word
For
eoch
18-bit
word
received,
the
1540
received,
the
1540
writes 5
fromes
writes 6
fromes
on
the
tope:
2
fromes
on
the
tope:
3 fromes
of
zeros
foJlowed
by
of
zeros
followed by
3
do
to fromes. 3
doto
frames.
For
eoch
36
-bit word For
eoch
36-bit
word
received,
the
1540
received,
the
1540
writes 5
frames
writes 6
frames
on
the
tope.
Since only
on
the
tape.
Mod 6
is
the
30
lSS
are
written
recommended
for
the 6
MSB
ore
"lost."
duol
chonnel
Mod 5
is
commonly
operation.
used
when
preporing
topes
for
the
30-bit
computers
KP-642B,
1206,
or
1230).
far
eoch
30-bit
word
For
eoch
30·bit
word
received,
t
he
1540
r
eceived,
the
1540
writes 5 fromes writes 6
fromes
on
the
tope.
Mod 5 is
on
the
tope:
1
frame
recommended
for
of
zeros
followed
by
operation
with CP- 5
dato
frames.
Mod
642B,
1206,
or
1
230
6
is
commonly
used
Computers.
when
pr
epa
ring l
opes
for
36-bi
t
computers.
4 read
in
g operations, four tape frames are assembled
as a 24-bit computer word for
Bi-
octal Character
format
or
eight tape frames are assembled as a 24-bit
computer word for Octal Character format. If the
computer word s
ize
is
larger than 24 bits, the frames
are assembled
in
the lower order 24 bi
ts
and zeros
are placed
in
remaining high
or
der bits
(s
ee Figures
9 and 10
).
as
five
tape frames of Bi-octal Character
fo
rmat
or
ten tape frames of Octal Character format.
If
a com-
puter delivers a word larger than 30 bits for record-
ing, the Magnetic Tape Control
will
record the lower
o
rd
er 30 bits of the word on the tape and discard the
remaining
hi
gh order bits. During Mod 5 reading
operation
s,
five
tape frames are assembled as a 30-
bit computer word for Bi-octal Character
fo
rmat
or
ten tape frames are assembled as a 30-bit computer
word for Octal Charact
er
format.
If
the computer
word size
is
larger than 30 bits, the frames are
as
-
Modulus 5 (designator bits
[0
and 09 =
10
)
-A
30-bit computer word is disassembled and recorded
14
sembled in
th
e lower
order
30
bits and zeros
aTC
placed
in
remaining
hi
gh
order
bits (see Figures 9
lmd 10).
.\lodll/lls 6 (designator bils 10 and
09
= 11) - A
36·bil
computer
word
is
disassembled and recorded
as s
ix
tape frames
of
Bi-OClal
Character
format
or
twelve tape frames
of
Octal
Character
formal. Dur-
ing Mod 6 reading operations. six
tape
frames
are
assembled
as
a 36-bil computer word for
Bi
-octal
Character format
or
twelve tape frames 3Te assem-
bled as a 36-bit computer
wo
rd for Octal
Character
format. (See Figures 9 and
10.
)
Pority Desigll(ltor (Bit
7),
1 Selects Odd; 0 Selects
Ev
en
Either
Odd
(the total number of ones in a frame
is
odd)
or
Even (the lotal number of ones in a frame is
even) Lateral Parity may
be
specified
in
the In
str
uc-
tion Word for
Bi
-octal
Cha
racter writing and r
ead-
ing operation
s;
however,
Odd
Parity is se
le
cted by
th
e Magnetic Tape Control f
or
th
e Octal Character
writi
ng
and read ing operations.
Fo
r compatible
tapes,
Odd
Parity is chosen for Binary data coded
and Even Parity is chosen for Binary Coded Decimal
(BCD) data.
Density
Designator
(Bits
6
and
5)
()()
selects 200
!.Pi;
10
selects 556 fpi;
01
selects 800
fpi
; amI
'11
se ects same density as last ins
truction
At low density,
data
are record
ed
at 200 frames per
inch, at medium densi
ty
555.5 frames per inch, and
at
hi
gh density
800
frames
per
inch. Den
si
ty must be
specified
in
In
st
ruction Words requesting reading or
writing operat ions. Refer to Table 1 for word as-
sembly and disassembly time.
Operation
Code
Th
e
Ope
rat
io
n
Code
is located in Bits 15-11 of the
In
st
ruc
ti
on Wo
rd
. Le
ga
l
operat
ion codes exist
fo
r
the six basic
opera
tions and for combinations
of
these operation
s.
The
six basic opera
ti
ons arc Duplex
Selection, Read, Search, Write, Space File, and Re-
wind, Operation Codes using any basic
opera
tion
(except Rewind) must
be
supplemented by
Format
and Density codes placed in bits 10-07 and bits
06
and
05
respecti
ve
l
y,
of
the Instruction Word. Table
3 is a listing
of
the
Ope
ration codes and Fi
gu
re 8
shows the structure of the elllire instruction word.
Read OperatioWl
Th
e selected transport moves tape at 120 inches per
second in either direc
ti
on and transfers seven-bit
15
frames (read from tape) to the Magne
ti
c Tape
Con-
trol.
IJ
arity. even
or
odd. as specified in the Format
is checked
fo
r cach frame
of
th
e record.
Th
e s
ix
data
bits are assembled
in
to
18
-. 24-,
30
-,
or
36-bit com-
puter words according to the Modulus and
Character
designator of the Format. TIle assembled
comp
uter
word
is
placed on the data lines of the computer
in
-
put cable and the Input Request (IR) line
is
set.
The
computer
samples the
data
lines at its
co
n
ve
ni
ence
and sets the Input Acknowledge line to the Magnetic
Tape
Control.
The
tape
co
nt
inues to move and new
words are being assembled until
th
e End of Record
(Interreeord Gap)
is
reached. The computer
mu
st
sample the input lines and acknowledge
e;:lch
IR
within a specified lime (govern
ed
by
Density, Char-
acter, and
Modulus-Table
I)
(0
prevent loss
of
one
or more words
in
the record.
If
the computer fails to
sample
th
e input lines and
ac
knowledge the IR wit h-
in
the allotted lime during any type of Read Oper-
at
ion. an Input Timing Error will occur and
th
e
Magnetic
Tape
Control wi
ll
cease to transfer data to
the computer for Ihe remainder of
th
e record. Fol-
lowing the detection
of
the End of Record, the Mag-
netic
Tape
Control will set an Input Timing Error
Status Word on the input lines and interrupt the
computer program by setting the External Interrupt
(E
I) line on
that
channel. When
th
e computer
acknowledges the Interrupt,
the
MTU
becomes
R
EADY.
In a
ll
types of Read Operations. F
orma
t and Dcn
si
ty
selec
ti
ons must
be
made
in
each instruction.
Read-Forward
Th
e selected
transpon
will read one re
co
rd accordi ng
to the Format stated and check each frame for
parit
y.
If
a parity
error
is
detected, the Magnetic
Tape Control will continue
to
transfc r data to the
computer for the remainder
of
th
at record. After
sensing the End
of
Record, the Magnetic
Tape
Co
n-
trol
will
send a Status Wo
rd
to
th
e
computer
with a
signal on the External Interrupt lin
e.
This Status
Word will contain
MTU
status and any or a
ll
error
indica
ti
ons encountered during the reading of
th
e
record.
R
ead·Backward
The
selected transport w
ill
read one record back-
wa rd to the next Intcrrccord
Oap
(ba
ck
one record)
according to Format and Density stated in the In-
struction Word. Lateral and longitudinal parity w
ill
TABLE 3.
OPERATION
CODES
OPERATION
OPERAT
I
ON
CODE
00000 Read (Read
Forward
)
00001 Read: Selective (Selective Read-Forward)
00010
Read: Modified Stop
000
11
Space
File
00100
Se
arch
Type I
00101 Search Type
II
00110
Search File Type I
00111 S
ea
rch F
il
e
Type
II
0 1000 Write
0100
1 Write
XIRG
01010
Wr ite
Ig
n
ore
Error Holt
01011 Write
XIRG,
IgnQre Error Halt
01100
Wr ite Modified Stop
0110
1 Write Edit
0
11
10 Write Tape Mark
0111 1 Write Tape Mark,
XIRG
10000 Back
read
(Read Bockward)
10001
Bochead
Selecti
ve
(Selective Read-Backward)
1
0010
Bo
chead
Modified Stop
10011 Backspace
Fi
le
10 1
00
Backsearch Type I
10101 Back
search
Type
II
10 110 Backsearch File T
ype
I
10111 Backsearch
Fi
le Type
II
11000 Rewind
1100 1 Rewind,
Clear
Write
Enable
11010 Rewind
1101 1
Re
wind,
Clear
Write Enable
11100
Re
wind-Read
1
11
0 1 Rewind -Read,
Clear
Write Enable
1
11
10 Rewind·Read
11111 Request Tronsport·Stat
us
Bi
ts 17, 16 a nd 6 =
1,
a
and
I, respectively, Transmit Extra
be
checked while readin
g.
If an error is detected
dur
ing backward motion, the r
ea
ding operation will
co
ntinue and the Status Word, upon detection
of
Intcrrecord
Gap,
w
ill
co
ntain the
MT
U status and
the
error
indica
ti
on. Characters
wi
ll
be
assembled in
each computer word in the same posi
ti
on as in a
forward read.
Co
m
pu
ter words, however, will be
transmitted in reverse orde
r.
16
Read-Modified Stop
The
selecled transport w
ill
read one record accord·
ing to the Format stated and w
ill
ch
eck
each frame
f
or
parity. At the
co
mpletion
of
tb
e read, the
ma
g-
netic tape w
ill
be
stopped farther in the IRG.
Th
e
Status W
or
d sent to the computer after detection of
End of R
eco
rd w
ill
co
nt
a
in
MT
U st
at
us a
nd
any or
a
ll
crr
or
ind
ic
ations including
par
it
y error.
Selective Read-Forll;ard/Backwarcl
The
se
lected transport will read one record accord-
ing to the Format stated and check each frame for
parity. Words are read and assembled as
in
a Read-
Forward/Backward. A Selective Read Code, con-
tained
in
th
e least significant six bits (05-00) of a
computer
wo
rd.
is
sent by a single word output buf-
fer to
th
e tape unit before
it
can read and assemble
one word. Should this word be formed before the
Selective Read Code
is
transmitted, an Output Tim-
ing Err
or
is
detected. The Magnetic Tape Control
wi
ll
compare the least significant six bits (05-00) of
each assembled computer word with the Selective
Read Code. If the comparison
is
negative, the word
w
ill
be discarded
and
the reading cominued. A pos-
itive comparison causes the word to be transmitted
to the computer. However. if a parity error is de-
tected
in
either case, (urther transfer
of
data ceases
for
th
e remainder
of
the record. The Staus Word
sent to
th
e computer after detection
of
End
of
Rec-
ord will contain Magnetic
Tape
Unit status a
nd
any
or
a
ll
error indications.
Write Operation -Generollnfonnatiorl
When the Magnetic
Tape
Control senses a
WRITE
function, the selected transport moves the tape
fo
r-
ward a
nd
records
the
lnterrccord
Gap.·
A signal is
p
la
ced on the computer Output Request (OR)
li
ne.
The computer,
at
its convenience,
re
sponds with a
word on the data lines and places a signal on the
channel Output Acknowledge (OA) line. The Mag-
ne
ti
c Tape Control recognizes the OA, samples the
da ta
lin
es, and remo\'es the Output Request.
Th
e
word is transferred to the disassemb
ly
register a
nd
another Output Request
is
issued. The Magnetic
Tape
Co
ntrol disassembles each
wo
rd according to
the modulus
se
lected
in
the Write Function W
or
d,
generat
es
frame parilY, and transfers the seven bits
to the transport for recording on tape accord
in
g to
th
e density selected. As the
re
cord
in
g frame passes
over the read head
it
is checked
fo
r parity.
If
a parity
err
or
is detected, the Magnetic Tape
Co
ntrol stops
the Write operation and the tape motion. A Status
Word, indicating an error
in
recording,
is
placed on
the cha
nn
el
input lines with a signal on the External
Interrupt line.
If
no error occurs during recording,
the process conti
nu
es
until the computer no longer
acknowledges the Output Request within the time
alloued for anoth
er
word to be disassembled and
wriuen. This ti
me
is
depende
nt
on Format a
nd
Den-
-
The
normal lnterrecord
Gap
is
approximalely * inch
in
length and
Ih
e Extended Interrecord
Gap
is
approximately
3M:
inehes in length.
17
sity (refer to Table I). When the computer does not
respo
nd
within the allotted time, the End
of
Write is
assumed by the Magnetic Tape Control. Longitudi-
nal parity
is
written and the recording process is
terminated. Tape motion
is
stopped after a por
ti
on
of the !nterrecord
Gap
is written on the tape. The
Magnetic
Tape
Control removes the Output Request
and places a Status Word, indicat
in
g successf
ul
com-
pletion
of
the Write, on the input lines a
nd
sets
th
e
External Interrupt line. When the computer ac-
kn
owledges the Interrupt. the Magnetic Tape Sub-
system becomes I
OLE.
If the computer acknowledges
th
e Output Request after the allotted time but before
the interrupt is sent, the Magnetic Tape
Co
ntrol
interprets the action as an Output Timing Error and
not
ifies
the computer
in
the Status Word.
Writ
e
The
se
le
cted
transpon
will write on the tape accord-
ing to the Format and Density stated
in
t
he
Function
Word.
If
no recording error is detected the normal
operation continues until the computer no longer
transfers data,
at
which time longitudinal pa
ri
ty is
written and
th
e Status Word with Interrupt
is
se
nt
to the computer.
Write·/
gnore Error Halt
The selected transport will write on the tape accord-
ing to the Format and Density stated in
th
e Function
Word, but the Magnetic Tape Control will not stop
the writing process if lateral parity errors are de-
tected
as
the recorded frames pass over the read
head. The Status Word sent to the computer with
Interrupt after completion
will
contain MTU Status
a
nd
any or all errors encountered.
Write·Ert
el1c1ed
Interrecord Gap (X
IRC
)t
Th
e selected transport will record an Extended Inter-
record Gap
of
31h inches instead of the normal
~
inch IRG preceding a normal Write portion of the
operation.
If
no data are transferred from the com-
puter for recording. the Extended (
Dter
record Gap
wi
ll
be present
on
the tape and an Output Timing
Err
or
will occur.
The
Status Word sent to the com-
puter after completion
will
contain MTU status and
any
or
all error indications detected as in a normal
Write operation.
Write Tape Mark
The
se
lected Iransport wilt write a fixed fo
rm
at
Tape
Mark. The Tape Mark is a special record having
tSpecia
l
Le
ngth interreeord
Gap
-Under program con-
Irol, interrecord Gaps other than the
fi;l(ed
* inch a
nd
3!/.z
inch lengths may be written. Successive *
or
3!/.z
in
ch
ga
ps
ma
y be written
by
issuing the appropriate Write
functions without initiating output buffcrs al the computer.
The program
must
be
prepared
to
handle the Output Tim-
ing Error that will
be
in
dicated in Ihe Inte
rr
upt Status
Word following each Write operation performed
in
th
is
manner.
ooes in only the 0-,
I~,
2~
,
and
3~bi
t
positions
of
the
tint
frame, followed by
thr
ee frames of zeros and one
frame of longitudinal parity.
The
entire record is
9i
ntten by the Magnetic Tape Control
upo
n recei
v-
ing the Instruction Word.
Format
selection can be
ignored.
To
be
compatib
le
with
other
tape systems,
the
Tape
Mark must be exactly as specified above.
A Status Word with I
nter
rupt is sent to the
comp
ut
er
after completion
of
the Write
Tape
Mark operation.
Space File-Forward/Backward
The
selected transport w
ill
move the
tape
in the
selected direction to the IRG (beyond
th
e n
ex
t tape
mark).
Th
e
tape
is properly positioned
in
the IRG
for reading or writing.
Format
and Density must be
stated in the Instruction W
or
d sin
ce
parity will be
checked during
the
tape motion. Any error detected
and
MTU
status will be indicated
in
the Status Word
sent to the computer with I
nt
errupt after
comp
letion.
If the tape is at
Load
Point at the time
the
Back
Space or at End
of
Tape
at
the time the Space File
instruction is gi
ve
n, an Impr
oper
Co
ndition exists
and will be noted in the Status Word.
Rewind
The
selected transport w
iU
rewind
the
tape
backward
to the Load Point at rewind speed.
The
Status'Word
with lnterrupt
is
sent to the computer after the
M
ag~
netic
Tape
Control initiates the Rewind and not
at
the complet,ion of the Rewind.
If
the
tape
is
at
Loa
d
Point when
the
instruction is received, no
tape
mo-
tion
or
Improper Condition will result,
but
the Status
Word will indicate Load
Poi
nt. This provides a
me
th
od of testing for
co
mple
ti
on
of
the
Rewind
operation.
Multifunction Operations (CeMral
Inf
onnation)
Multifunction Operations consist
of
combinations
of
basic operations
of
the
MTU,
and
ca
n
be
perform
ed
in response
to
the
one Instruction Word from
th
e
computer. Examples
are
the Search operations which
co
mbine the features
of
a Read with the ability to do
a search on the first word
of
records,
compare
these
wo
rds against an Identi
fi
er (Search Key) Word, and
read on a
"Fi
nd." Othcr Multifunction Operations
combine a Read with a Rewind
operat
ion.
COll1b
i
na~
tions
of
functions such as these save on
computer
instructions, and provide some capabilities that
can
~
n
ot
be achieved by using the basic opera
ti
ons
one
at a time.
·
In
a forward Scan;:h, the first word encountered
in
each
re<:ord
is
the first word
of
the record. In a backward
$earch, the first word encountered
in
each record is
th
e
last word
of
the record.
18
Search (TYIJe I
and
Type
II
-
Forwon/
/
Ba
c
kward
)
Th
e Search Operation combines the features
of
R
cad
Forward
/Backward and a Search.
The
selected
tape
transpor
t 'w
ill
read records from the
tape
ei
th
er
for-
wa rd
or
backward and
compare
the
fir
st word· of
each tape re
cord
with a Search Key (Identifier Word)
which
is
transmitted from the comput
er
to the
MTU
by an output buffer of one word. When a compare
is
affirmative, that "
FIN
D" record is transmitted
to
the computer as in a
Read
Forward/Backward
.
Tape
motion is started upon receipt
of
the Instruc-
ti
on Word.
If
the
MTU
does not receive
the
Search
Key from the computer before it starts reading the
record, an
Output
Timing
Erro
r wi
ll
occu
r.
This
reading start time may
be
as short as two and on
e-
half milliseconds.
The
Search operation will
be
ter~
minated by
th
e Magnetic
Tape
Unit when this timing
error
is
detected by the Magnetic
Tape
Co
ntrol.
The
Status Word containing
MTU
sta
tu
s and any or a
ll
error
indications will be sent to
the
computer
upon
detecting
the
end
of
the record in
wh
ich
th
e err
or
occurred. When the
tape
motion
is
stopped due
to
an error, the
tape
will
be
position
ed
in the Inter-
record
Gap
before the record in which the error
occurred
if
the motion
is
backward, and after the
record if the motion is forward. A parity error
ca
n
result from a fau
lt
y parity check on any frame
of
the
tape
being searched.
The
ONES
(Type I)
co
mpare is a
bit~by-bit
"gr
e
ater~
tha
n-or-equ
al"
compare
. H the first word
of
the
record is greater than
or
equal
to
the Search Key
Identifier word, a "Find" is made. A six-bit example
is
shown below.
Search Key
or
Identifier W
ord
FIND;
if
fir
st word is
FIND
;
if
fir
st word is
NO
FIND
; if first word is
NO
FIND;
if first word is
001101
01
1
101
001
1
01
010101
001
100
The
IDENT
I
CAL
(Type
II
)
compare
is an exact
equal compare.
The
fir
st word
of
the
record must
be
exactly equal to the Search Key Identifier word to
define the
"FIND
"
re
co
rd.
Searc11
File§
Forward/Backward
The
Magnetic
Tape
Control
will
perform a Search
Forward/Backward
Type
I
or
Type
II
as directed
by operation code,
on
the selected
tape
transport ,
unt
il it
detects a
"Fi
nd" or a "
Tape
Mark"t
.
If
a
§A
File is defined as one
or
more records separated by
Tape Marks (see Figure
II)
.
tA Tape Mark
is
a speci
al
record
on
a tape placed
th
e
re
by
the operation
"Wnt
e Tape Mark." (see Figure 6).
Tape
Mark
is
detected before a
"Find;'
the
Search
File operation will be terminated and the
Tape
Mark Status Code will be present in the Status Word
se
nt
to
the computer after detecting
End
of
Record.
Sp(lce File Forward/Backward
The
Magnetic
Tape
Control will cause the selected
transport
10
move the tape in the specified direction
to
th
e Interrecord
Gap
beyond
the
next
Tape
Mark
and will indicate
Tape
Mark in the Status Word sent
to
the
computer
detecting the End of Record (see
Figure
II).
Space File Forward will position a
tape
at A upon completion; Space File Backward will
pos
iti
on the tape
at
B.
Rewind-Read
The selected transport
\\;
ill Rewind the
tape
to the
Load
Point
at
rewind speed and then perform a
Normal Read of
the
first record according
to
the
Format and
OI;:nsit}
stated in the Instruction Word.
A Status Word containing
MTU
status and any
or
all errors
....
i11
be sent
to
the computer with Interrupt
after detecting the
End
of
Record.
Rewind-Clear
Write
Ennble
The selected transport will perform a normal Rewind
of the tape
to
Load
Point and will clear the Write
Enable. This selected transport will no longer per-
form a Write function without manual intervention.
The
Status Interrupt will
be
presented upon initi-
ation
of
the
Rewind and not upon completion.
rAPE FORWARD DlREc
r:o
"-J
F
ilE
Rewind-Read-Clellr Write Ellllble
The
selected transport will perform a Rewind-Clear
Write Enable and
th
en a Normal
Read
of the first
record in the forward direction according
to
the
Fo
rmat stated
in
the Instruction Word. A Status
Word containing
MTU
status and any
or
all errors
will
be
sent
to
the computer with Interrupt after de-
tecting the End of Record.
Request Transport Status
No
tape
operation
is
performed.
The
MTU
sends a
Status Word reflecting the status
of
the selected
tape
transport to the computer with Interrupt. However,
when the "Not Ready" indication is obtained, the
remainder of the Status Word may not
be
valid as it
may have been derived from other handlers.
Transmit Extra (Bits 17. 16, and 6 = 1, 0, (Iud I.
respectively)
The
Transmit
Extra
Instruction Word
is
se
nt
under
program control in response
to
an
lnterrupt
indicat-
ing a
Frame
Count
Error
al
the
end of a Read oper-
ation. All
bilS
other than 17, 16, and 6
of
the
Instruction Word
are
ignored.
The
Transmit
E:r;:tra
provides
data
recovery capab
il-
ities by the transmission of a s
in
gle
dala
word
containing the extra characters of an incomplete
computer word (6 bits per
cha
racter) and denoting
those c
har
acter positions void of data.
The
extra
characters will appear in the most significant char-
I~
____________
~A~
____________
~
\
,
P
05!110N
REC
ORO
TAPE
MARK
RE
CO
RO
S
I
I\~HNG
POSiTrON
RECORD RECORD
Figure 11. Magnetic Tape Unit -Tape File
19
•
POSITION
acta"
po..o"",
erll
",irn
the specified modulus.
Ea..,.
~
the
~
..
ignificant six will refer
to
a
clw'xttt
ro;ition:
in
the
word
or
iginating
in
the
\ ;nctJo:
T~
Control
a~~mbly
registe
r.
All bits
it'1e)
the
modulu\
limi\!-;
will
contain
D's.
When
-
~tt
.3
brt
In
~
lea~t
signific3m character
is
I. the
corre.pondmg
character
in
the
assembly register is
LQr.dil:t
.....
hcn a
bit
i~
O.
the corresponding
character
IS
\'3Jid
'>CC
!-Igure 12).
In
the
redundant
format.
the
lack
of
one
frame
(char-
acter!
....
auld
n
OI
allow the last fnunc to enter the
a
....
embly
rcgi~tcr
a
nd
the frame would be lost. How-
ever. this would
be
a valid Improper
Frame
Cou
nt
and
would
be
accompanied by a Longitudinal Parity
Error.
MAGNETIC
TAPE
UNIT
-
HIGH
-
SPEED
PRINTER
OFF
-LINE
CAPABILITY
Either
MTU
is
capab
le of communicating directly
with a UN I
VAC
Hi
gh-Speed Printer f
or
OFF-
LI
NE
operat
ion.
The
MTU
communicates with the High.
Speed Printer Unit
in
the Rcques
t·A
cknowlcdge
[ " '
"'
"'ME
INDIC.A10R
BIOCtA(
ASSEMBLED
WORD BINARY
,
, • 3 2 ,
(,I
I ' , 3 2 , 0
u , w , ,
00
' 0 0 0 0 0 0
, w , , zt
00
0 0 0 0 0 0
w , , 2
.,
0 0 0 0 0
, , 2
03
0 0 0 0 MOO 6
, 2 " 0 0 o ,
2 " 0 0 , ,
, w , ,
00
-0 0 0 0 0 0
w , , 2
00
0 0 0 0 0 0
, • 2
.,
0 0 0 0 0 MOO 5
, 2 03 0 0 0 0
" 0 , ,
t'
T
L
_____________
___
L
_______
MOD
5 LIMIIS
w , ,
00-
0 0 0 0 0 0
, , 2 00 0 0 0 0 0 0
, 2 " 0 0 0 0 0 , MOO 4
03
0 0 , ,
l' T
'-----------------''-------
MOO 4 UMIIS
, ,
00
' 0 0 0 0 0 0
, 2
00
0 0 0 0 0 0 MOO J
" 0 0 0 ,
r
't'
'---------
----
----'-------
MOO 3
LIMITS
t z
denole.
10.1 1,0"" . Y
denol
e • • e
tond
10.1
I""
...
.
elc.
A
'·
0" in Ih
...
1'0
/'0"'10'
indicoto,
d.nol
••
°
volid
hom.
01
dolo
'"
".
c
o"e.ponding
l'O'".ion "
",
compule<
wo,d
wjlhin
Ihe
",odulu.
Ii
..
ils.
·
Th
.
wo.d
il
id
e
nlOcol
with
.h
e lost
(normoll.,
I,
on.",ill.dl
wo.d
• • C.PI I
hot
Ihe
Zo
hOI
been
dest
,oy
ed
.
no
eAI.o 1
.0"',..
0
••
pre.enl
.
ond
Ihe
I
.on.mil
e
xt.o
<om"'ond
should
nOl
hove
been
u.ed
. Figl/re 12. Transmit-Extra Compl/ler
\V
ord Format
20
mode
.
(T
he M
agnetic
Tape-Printer
Inte
rface is
shown
in
Figure 13).
Using terms based on Computer-Magnetic
Tape
Unit
commu
ni
cation and Computer-High-Speed Primer
communication
in
this discu$.sion. the Output to the
High-Speed Primer imerface
is
connected
to
the
Input from the Magnetic
Tape
Unit i
nterf<l
ce. i.e"
the High-Spe('d Printer Output Request line
is
con-
nected to the Magnetic
Tape
Unit Input Acknowl-
ed
ge
line: the
MTU
Input Request lillc
is
connected
10
the
Hi
gh-Speed Primer Output Acknowledge line:
th
e MTU Interrupt line
is
co
nnected to the High-
Speed Printer External Function line: the
MT
U dnta
lines a
rc
connected to the
Hi
gh-Speed Printer
data
lines.
The High-Speed Printer exe
rci
ses control of the
OFF-LIN
E
s~
s
tem
after the MTU
is
sw
itched to
Printer Mode. the desired tape transport is selected.
and the tape is positioned at L
oa
d Point.
The
H
igh
-
Spe
ed
Printer
will
initiate the operation when
it
is
placed in
OFF
-L1i'E
position.
The
data
on magnetic tape
to
be
printed
OFF
·
L1
NE
must
be
recorded in t 20 Fieldal3 character record
lengths (120 characters per
li
ne on
Hi
gh-Speed
Printer
).
As
each record
is
read from
th
e tape and
transmined to the High-Speed Printer. the 120 char-
acters arc primed as o
ne
line and the paper
is
ad-
va n
c~d
10
the next line position. Each 30-bit
wo
rd
delivered to the High-Speed Printer must
co
nt
ai
n
five
Fieldala Code
cha
racters (refer to Table 4).
Th
ese are
in
tum
disassembled into six-b
it
characters
and stored in the character
co
re memory of the
Hi
gh-
30
DA
1A
•
OUT
P
UT
D
ATA
IIEOUEST
OUT
PUT
AC
KNOW LEDGE
EXTERNAL
FUNC
TI
ON
Speed Printer
Con
trol Unit.
One
word can
be
stored
each
S'"
l11icro~cconds.
(Refer to Table I for record-
ing d
...
n
~
it
y
limi l;J!ions.) When the core memory
character cou
nt
er indicates 120 characters, the print
c~c1e
is
in
it
iated and the line
is
printed. A record
of
less
th
rln
24 thirty-bit words w
ill
indicate to the
High-Speed
Pr
i
nt
er to
~
top
the pri
nt
operation. A
re
cord
of
the
'pace
codes (OS) w
ill
S
lOp
the print
opera
ti
on \\ i
th
out printing a line.
Operating
Instructions
To
prepare the
OFF-LINE
MT
U High-Speed Pri
nt
er
system for operation the operator must se
le
ct:
• Chnr:lcter.
parit~.
a
nd
density of the recorded
tape at the
\iT
U
cab
inet;
• Switch the
~1T
U
to
Printer Mode;
• Select
th
e de.,ired tape transport:
• Load and
po~ition
the tape at Load Point :
•
Pl
ace the Hi!!h-Speed Printer
in
OFF-LINE
position.
Sequence
of
Events
The nor
mal
sequence
of
events for transfer
of
data
to the
Hi
!!h-Specd Printer is
a~
follows:
• High-Speed Printer sets its Output O;
lI
a Re-
queSt:
• Magnetic
Tapc
Subsystem.
in
the REA
DY
state. recognizes the first Output Data Re-
liNES
I
NP
UT
ACKNOWLEDGE
INPUT
DA
TA
REOU
ESt
INIERRUPT
Fi
g
ur
e 1
3.
Ma
gnetic Ta pe -Printer Interface
2 1
TABLE 4. TYPE
SYMBOLS
AND
CODES
Odcl
Bin
or
y Octol Binory
C
ad.
cad.
Choracter
Cad.
Code
Charader
00
000 000
I Absolute
Value
'0
100000
J
01
000
001
I Arrow (Up) " 100
001
-
02
000010
8 Subscript Eight
'2
100010
+
03
000011
[ Broc
ke
t {
Open}
43
100011
<
O.
000
100 1 Bracket
(Close)
"
100100
•
05
000
101
Space
(Unde
rcut) 45 100
101
>
06
000 110 A . 6 100 110
~
Equal to
or
Less Than
07
000 1 I 1 B 47 100
111
t
Left
-Hond
Br
a
ce
10
001
000 C 50 1
01000
• Star
II
001001
0
51
101001
I
12
00 1
010
E
52
101010
~
Equal to or
Grea
ter Than
13
001011
F
53
101
01
1 ·
"
001
100 G 54
101
100 I
Ri
ght
-H
ond Broce
15
001
10 1 H
55
101
101
v (Or)
16
001
11
0 I
56
101
110
17
0011'
1 J
57
101
'1 I t
20
010
000 K
60
110000
0
21
010001
l
61
110001
I
22
010010
M
62
11
00
10 2
23
0 1
0011
N
63
110011
3
2'
010 100 0 64
110100
•
25
0 10
101
P
65
110 10 1 5
26
0101
10 Q 66
110110
6
27
010111
R 67
11011
, 7
30
011000
S
70
111000
B
31
011001
T
71
111001
9
32
011010
U
72
111010
" And
33
01101
\ V
73
111011
3' Oil
100
w 7'
III
100
!
35
Oil
101
X
75
111 101
36
Oil
110
y
76
11
\ 110 _
ArrC1H
Right I
37 Oil
III
Z
77
III
111
x Multiply Sign
22
qu
es
t as a co
mm
a
nd
to stan the read oper-
a
ti
on;
• The M
TU
places a word on the da
ta
lines
and
se
ts its
In
p
ut
Data Request:
• High-Speed Pri mer recognizes this Input
Data Request as an Output Ac
kn
owledge:
•
Hi
gh-Speed Pri
nt
er samples the data
li
n
es
and clears its Output Data Request:
• M
ag
net
ic
Tape Unit recognizes
th
e clearing
of the Output Data Request
as
an I
np
ut
Ac
kn
o
wl
edge.
23
The laHer
fou
r steps arc repeated until the co
mpl
ete
record is
tm
nsfcrrcd, at wh
ic
h
ti
me
th
e line
is
printed,
th
e paper
is
advanced, a
nd
the cycle
is
r
ei
ni
ti
:lled. T
he
process cont
inu
es until
th
e End of
F
ile
Tape Mark is read. T
he
H
ig
h-Speed Printer
recognizes the Tape Mark as a comma
nd
to position
the paper at
Top
of Form on the n
ex
t page. The
In
te
rru pt line of the Magnetic Tape Unit be
in
g con-
nected to the External Funct
io
n
li
ne
of
th
e High-
Speed Printer permits the E
nd
of Reco
rd
;l
nd
the
Tape Mark Codes
to
be
se
nt
to
th
e
Hi
gh-Speed
P
ri
nt
er :IS commands to move paper one
lin
e space
or
Top
of Form respectivel
y.
