HP Flexible Disk Formatsx Formats
User Manual: HP Flexible Disk Formats
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HP Flexible Disk Formats
Martin Hepperle, June 2016
Nomenclature
0.5 MB media is typically 250…360 KB formatted (SS/DD)
1.0 MB media is typically 600…720 KB formatted (DS/DD)
2.0 MB media is typically 1.20…1.44 MB formatted (HD)
Product 0.5-Mbyte Media 1.0-Mbyte Media 2.0-Mbyte Media
HP 9122D/S E D N
HP 9122C E/2 D/2 D
HP 9123D E/2 D N
HP 9133D/H/L E D N
HP 9153C E/2 D/2 D
D = Recommended for daily use.
D/2 = Recommended for daily use; data transferred at one-half the normal rate.
E = Recommended for data exchange only.
E/2 = Recommended for data exchange only; data transferred at one-half the normal rate.
N = Never use; product unable to identify 2-Mbyte media.
Table 1: Flexible Disk Media Usage as Recommended by HP.
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity
HP 256 30 67 1 2010 514'560
Table 2: Format Data, HP 9885M, 9885S, 8-inch SS/DD media. For 9800 Series, 21MX and similar machines.
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity
HP 256 30 77 2 4620 1'182'720
IBM 128 26 77 1 2002 256'256
Table 3: Format Data, HP 9895A, 8-inch SS/DD media. For 9800 Series and similar machines.
Format Bytes/Sector Sectors Tracks/Side Sides Sectors Capacity
INITIALIZE 256 16 70 (−4 = 66) * 1 1120 (1056) 286'720 (270'336)
* The HP format uses 4 spare tracks so that 66 remain. The values given for Sectors and Capacity are for the
complete disk, values in parentheses subtract these spare tracks and represent the true available capacity.
Table 4: Format Data, HP 85, with 9121S, 9121D, 9133A disk drive, 3½-inch DD media.
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity Typical
0,1 256 16 77 (−2 = 75) * 2 2464 (2400) 630'784 (614'400) 9000/200
2 512 9 77 (−2 = 75) * 2 1386 (1350) 709'632 (691'200) HP 150
3 1024 5 77 (−2 = 75) * 2 770 (750) 788'480 (768'000)
4** 256 16 70 (−4 = 66) * 1 1120 (1056) 286'720 (270'336)
16 512 9 80 2 1440 737'280
* The HP format uses 2 per side (resp. 4 spare tracks for single sided disks) so that 66 resp. 75 remain. The values
given for Sectors and Capacity are for the complete disk, values in parentheses subtract these spare tracks and
represent the true available capacity.
** Option 4 can be used to format single-sided 0.5-Mbyte media as well as double-sided 1-Mbyte media.
If a 1-Mbyte disk is formatted with Option 4 only one side of the disk will be formatted. Option 4 is also produced
by the INITIALIZE command of the HP-85.
Table 5: Format Data: HP 9122C, 9122D/S, 9123D, 9133D/H/L, 9153A/B/C, 3½-inch DD media,
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity
0,1,4 256 32 77 (−2 = 75) * 2 4928 (4800) 1'261'568 (1'228'800)
2 512 18 77 (−2 = 75) * 2 2000 (2700) 1'419'264 (1'382'400)
3 1024 10 77 (−2 = 75) * 2 1540 (1500) 1'576'960 (1'536'000)
16 512 18 80 2 2880 1'474'560
* HP format uses 2 spare tracks per side resp. 4 for single sided disks. The values given for Sectors and Capacity are
for the complete disk, values in parentheses subtract these spare tracks and represent the true available capacity.
Table 6: Format Data, HP 9122C and 9153C, 3½-inch 2 MB (HD) media.
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity
256 16 35 (–2 = 33) * 2 1120 (1056) 286'720 (270'336)
* HP format uses 2 spare tracks per side so that 33 remain. The values given for Sectors and Capacity are for the
complete disk, values in parentheses subtract these spare tracks and represent the true available capacity.
Sector IDs are from 0 to 15.
Table 7: Format Data, HP 82901M, 82902M, 9130A, and 9135A, 5¼-inch DD media
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity
1* 256 16 35 (–2 = 33) *** 2 1120 (1056) 286720 (270'336)
2*,** 512 9 40 2 720 368’640
3* 1024 5 37 2 370 378’880
4*,** 512 8 40 1 320 163’840
5*,** 512 9 40 1 360 184’320
6*,** 512 8 40 2 640 327’680
* Formatting 5¼ inch media only.
** IBM compatible format.
*** HP format uses 2 spare tracks per side so that 33 remain. The values given for Sectors and Capacity are for the
complete disk, values in parentheses subtract these spare tracks and represent the true available capacity.
Table 8: Format Data, HP 9125S and 9127A, 5¼-inch DD media
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity Media Byte
1*,** 256 16 80 1 1280 327’680
2*,** 512 9 80 1 720 368’640
3*,** 1024 80 1
4*,** 256 16 80 2 2560 655’360
5*,** 512 9 80 2 1440 737’280 F9
6*,** 1024 80 2
* Formatting 3½ inch media only.
** IBM compatible format.
Table 9: Format Data, HP 9144, HP-150, MS-DOS, IBM-PC compatibility, 3½-inch DD media.
Format Bytes/Sector Sectors/Track Tracks/Side Sides Sectors Capacity Available
FORMAT /W 256 16 77 1 1232 315’392 264’192
FORMAT /X 256 16 77 2 2464 630’784 618’496
FORMAT /Y* 512 9 80 2 1440 737’280 700’416
FORMAT /Z 1024 5 77 2 770 788’480 780’288
* This format can be read by “modern” (2015) HD floppy drives (normally used with 1.44 MB disks) and is
therefore suitable for data exchange. Works e.g., with external USB floppy drives. Of course, the disk must be
DS/DD, 720 KB, not HD 1.44 MB. It is recommended to format such DS/DD disks on low capacity 720 KB drives
(not on HD drives).
Table 10: Format Data, HP 110 with 9114B disk drive, 3½-inch DD media.
Notes:
Number of Sectors / Disk = Sectors/Track * Tracks/Surface * Surfaces/Disk
Capacity denotes nominal, unformatted disk capacity in Bytes.
Depending on the file system, volume and directory entries or file allocation tables reduce the capacity
available for actual data.
Tracks/Side is also called Cylinders
HP Model Drive Manufacturer Drive Model Heads RPM Mode Tracks/Surface Command Set
9121D, S SONY
OA-D30V-1
OA-D31V-1
OA-D31V-14
1 600 MFM 70 AMIGO
9122D, S SONY OA-D32W-10
OA-D32W-11 2 600 MFM 80 SS/80
9122C SONY(?) 2 300 MFM 80 SS/80
9133A, B SONY OA-D31V-?? 1 600 MFM 70 SS/80
9133V, XV SONY OA-D31V-?? 1 600 MFM 70 AMIGO
9133D, H, L SONY OA-D32W-10
OA-D32W-11 2 600 MFM 80 SS/80
9114A, B SONY OA-D32W-10
OA-D32W-11 2 600 MFM 80 SS/80
9153A SONY
OA-D32W-10
OA-D32W-11 2 600 MFM 80 SS/80
9153A SONY 2 300 MFM 80 SS/80
82901M/S Tandon TM-100-2A 2 300 MFM 35 AMIGO
82902M/S Tandon TM-100-2A 2 300 MFM 35 AMIGO
9885M/S 1 360 MFM 67 SS/80
9895A 2 360 MFM 77 AMIGO
13272 Tandon TM-100-2A(?) 1 300 MFM 35 SS/80
64110A Tandon TM-100-2A(?) 1 300 MFM 35 SS/80
64100B Tandon TM-100-2A(?) 1 300 MFM 35 SS/80
9130A/K Tandon TM-100-2A 2 300 MFM 35
9135A Tandon TM-100-2A 2 300 MFM 35 SS/80
9126 Tandon TM-100-2A(?) 1 300 MFM 35
9836 Tandon TM-100-2A (?) 1 300 MFM 35
Table 11: Floppy Disk Drive Hardware.
