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Disk Contents of the
IBM® Personal Computer™ DOS
Version 1.00 (1981)


Copyright © 2005 by Daniel B. Sedory

NOT to be reproduced in any form without Permission of the Author !



DISK STRUCTURE

Absolute
Sector(s)
Size
(in bytes)
Sector(s) Contents:
0
512
Boot sector; also called Boot Record.
1-2
1,024
File Allocation Table area; 1 sector per FAT.
FAT1, and  FAT2 (copy of FAT1).
3-6
2,048
Single fixed-size Root Directory (64 entries*).
 
=====
3,584
(sub-total)
Sum of all System areas (Boot, FATs and Directory).
7-319
160,256
File area for (both system and user files).
 
=======
163,840
Total (for the whole diskette).
  163,840 bytes divided by 512 bytes/sector =
    320 sectors, Total, on a 160 KiB diskette!
*At 32 bytes per Directory entry, 2,048 / 32 = 64 possible entries.

DISK CONTENTS

See our Tech Notes on the difficulty of working with versions 1.00 and 1.10 of IBM®'s Personal Computer™ DOS; most notably, that you may not be able to use any other versions of DOS to copy files from these early diskettes unless the BIOS supports them. You can, however, still read the Directory under all later DOS versions [except in a Windows DOS-box] using the dir /a or dir /a:h commands (thus data about the two Hidden System files can be viewed when using much later versions of DOS):

 Volume in drive A has no label
 Directory of A:\

   File Name         Size    Allocated     Modified       Attrib

 IBMBIO   COM       1,920      2,048    07-23-81 12:00a     HS
 IBMDOS   COM       6,400      6,656    08-13-81 12:00a     HS
 COMMAND  COM       3,231      3,584    08-04-81 12:00a
 FORMAT   COM       2,560      2,560    08-04-81 12:00a
 CHKDSK   COM       1,395      1,536    08-04-81 12:00a
 SYS      COM         896      1,024    08-04-81 12:00a
 DISKCOPY COM       1,216      1,536    08-04-81 12:00a
 DISKCOMP COM       1,124      1,536    08-04-81 12:00a
 COMP     COM       1,620      2,048    08-04-81 12:00a
 DATE     COM         252        512    08-04-81 12:00a
 TIME     COM         250        512    08-04-81 12:00a
 MODE     COM         860      1,024    08-04-81 12:00a
 EDLIN    COM       2,392      2,560    08-04-81 12:00a
 DEBUG    COM       6,049      6,144    08-04-81 12:00a
 LINK     EXE      43,264     43,520    08-04-81 12:00a
 BASIC    COM      10,880     11,264    08-04-81 12:00a
 BASICA   COM      16,256     16,384    08-04-81 12:00a
 ART      BAS       1,920      2,048    08-04-81 12:00a
 SAMPLES  BAS       2,432      2,560    08-04-81 12:00a
 MORTGAGE BAS       6,272      6,656    08-04-81 12:00a
 COLORBAR BAS       1,536      1,536    08-04-81 12:00a
 BUG      BAS         640      1,024    08-04-81 12:00a
 CALENDAR BAS       3,840      4,096    08-04-81 12:00a
 MUSIC    BAS       4,224      4,608    08-04-81 12:00a
 DONKEY   BAS       3,584      3,584    08-04-81 12:00a
 BLUE     BAS       1,152      1,536    08-04-81 12:00a
 HUMOR    BAS         640      1,024    08-04-81 12:00a
 POP      BAS         768      1,024    08-04-81 12:00a
 FORTY    BAS         768      1,024    08-04-81 12:00a
 DANDY    BAS         640      1,024    08-04-81 12:00a
 MARCH    BAS         768      1,024    08-04-81 12:00a
 STARS    BAS         768      1,024    08-04-81 12:00a
 HAT      BAS         768      1,024    08-04-81 12:00a
 SCALES   BAS         640      1,024    08-04-81 12:00a
 SAKURA   BAS         512        512    08-04-81 12:00a
 CIRCLE   BAS       1,664      2,048    08-04-81 12:00a
 PIECHART BAS       2,304      2,560    08-04-81 12:00a
 SPACE    BAS       1,920      2,048    08-04-81 12:00a
 BALL     BAS       2,048      2,048    08-04-81 12:00a
 COMM     BAS       4,352      4,608    08-04-81 12:00a

       40 file(s)        144,725 bytes
         0 dir(s)        154,112 bytes allocated
                           6,144 bytes free
                         160,256 bytes total disk space,  96% in use

NOTE: Recall from the Disk Structure table above, there are only 160,256 bytes for the File area ("disk space" in CHKDSK), because the Boot Record, FAT and Directory structures must use 3,584 bytes of the disk's total capacity! The diskette does in fact contain 163,840 bytes (160 KiB) of accessible data; and we see that there's only 4% (or 6,144 bytes) left for user files.

Location of Files on Diskette

By forcing a disk editor to use its "Physical" (vs. "Logical") view of the diskette, we were able to discover the physical location of each file as follows [Note: Most system utility programs, such as WinHex, will not recognize this diskette nor its image file, so we've added a column showing the Absolute Sector location for the beginning of each file to help. Absolute Sector = Cluster + 5 ]:

 Absolute Sector 3
 -----------------                                  Absolute
   Name   .Ext    Size    Date      Time    Cluster Sector   A R S H D V

  IBMBIO   COM    1920   7-23-81  12:00 am       2      7    - - S H - -
  IBMDOS   COM    6400   8-13-81  12:00 am       6     11    - - S H - -
  COMMAND  COM    3231   8-04-81  12:00 am      19     24
  FORMAT   COM    2560   8-04-81  12:00 am      26     31
  CHKDSK   COM    1395   8-04-81  12:00 am      31     36
  SYS      COM     896   8-04-81  12:00 am      34     39
  DISKCOPY COM    1216   8-04-81  12:00 am      36     41
  DISKCOMP COM    1124   8-04-81  12:00 am      39     44
  COMP     COM    1620   8-04-81  12:00 am      42     47
  DATE     COM     252   8-04-81  12:00 am      46     51
  TIME     COM     250   8-04-81  12:00 am      47     52
  MODE     COM     860   8-04-81  12:00 am      48     53
  EDLIN    COM    2392   8-04-81  12:00 am      50     55
  DEBUG    COM    6049   8-04-81  12:00 am      55     60
  LINK     EXE   43264   8-04-81  12:00 am      67     72
  BASIC    COM   10880   8-04-81  12:00 am     152    157

 Absolute Sector 4
 -----------------
  BASICA   COM   16256   8-04-81  12:00 am     174    179
  ART      BAS    1920   8-04-81  12:00 am     206    211
  SAMPLES  BAS    2432   8-04-81  12:00 am     210    215
  MORTGAGE BAS    6272   8-04-81  12:00 am     215    220
  COLORBAR BAS    1536   8-04-81  12:00 am     228    233
  BUG      BAS     640   8-04-81  12:00 am     231    236
  CALENDAR BAS    3840   8-04-81  12:00 am     233    238
  MUSIC    BAS    4224   8-04-81  12:00 am     241    246
  DONKEY   BAS    3584   8-04-81  12:00 am     250    255
  BLUE     BAS    1152   8-04-81  12:00 am     257    262
  HUMOR    BAS     640   8-04-81  12:00 am     260    265
  POP      BAS     768   8-04-81  12:00 am     262    267
  FORTY    BAS     768   8-04-81  12:00 am     264    269
  DANDY    BAS     640   8-04-81  12:00 am     266    271
  MARCH    BAS     768   8-04-81  12:00 am     268    273
  STARS    BAS     768   8-04-81  12:00 am     270    275

 Absolute Sector 5
 -----------------
  HAT      BAS     768   8-04-81  12:00 am     272    277
  SCALES   BAS     640   8-04-81  12:00 am     274    279
  SAKURA   BAS     512   8-04-81  12:00 am     276    281
  CIRCLE   BAS    1664   8-04-81  12:00 am     277    282
  PIECHART BAS    2304   8-04-81  12:00 am     281    286
  SPACE    BAS    1920   8-04-81  12:00 am     286    291
  BALL     BAS    2048   8-04-81  12:00 am     290    295
  COMM     BAS    4352   8-04-81  12:00 am     294    299

  Last used cluster/sector on diskette:        302    307

  Unused sectors at end of diskette = 12
(12 sectors x 512 bytes/sector = 6,144 bytes free space).

MD5 Sums for every File on the Diskette

For a complete introduction to using MD5 Sums (click here).
If you believe that one or more of the files on your DOS version 1.00 diskette have become corrupted, compare their MD5 sums with this listing:


  5f01e2438448c2fcbfcf296352cd5acd IBMBIO.COM
  3a1b572ec8958a796cd15bbaa99cefba IBMDOS.COM
  d572c3df143808773a0b0939fb9da381 COMMAND.COM
  ede9224c34be6e01fceb4d17ddc3337e FORMAT.COM
  9813bae4e76b904552f58a3a826a0ef1 CHKDSK.COM
  e1b70c19e40a68d90ff9dfc498ab7374 SYS.COM
  ffe1930af52e4f540f461a0c9c592843 DISKCOPY.COM
  a2dfdadcffc4208a2cdebebc9b66f07a DISKCOMP.COM
  fec33adb9ee657a21fc2711d89e6a84c COMP.COM
  432d0670686c7b1fe428063843855d3f DATE.COM
  66e912f7dcd34aabee47e0637d3b470c TIME.COM
  4ba98f31bb6f9bc06698cc3efe815fc1 MODE.COM
  78f7965a01690258f57abb89fa9e6f3c EDLIN.COM
  839c5f862c9e4c90a69aff70814dd5a7 DEBUG.COM
  2f11573f12d0bf5a60a62a50eef7e577 LINK.EXE
  4ac114a0894989489485ed08d52e9cb4 BASIC.COM
  9cb1db514ca75c1c9fd9c942ada25a5a BASICA.COM
   368a8b2d18b0881e80ef4a1e7e26d477 ART.BAS
   b08169f5b1f9886d69c8c209813df677 SAMPLES.BAS
   d6f25be6c0ffc6c4f05a6fe1e7078952 MORTGAGE.BAS
   49f9fe08571876a5d88e3844db35e12d COLORBAR.BAS
   03240ce0e0793b57be0f6201c8a01c26 BUG.BAS
   44251a6e5fc1b2f13d626488c35bde67 CALENDAR.BAS
   fe153b712dac1a50863768fb8ab7c29b MUSIC.BAS
   0bea43a247d7b22d45e19d263f88021f DONKEY.BAS
   c6309377f97a125cb0a9edc80d8f1f1e BLUE.BAS
   aa9b7d7e8457ee3edfed60620dbff8a9 HUMOR.BAS
   924b61e199bdfb13e2b74b20878c8d73 POP.BAS
   340a8b49f95f5e3b7a18806eac432f8a FORTY.BAS
   c2cee792871d26a5c5bfe2fcb7ee0511 DANDY.BAS
   80a7916e2c4d0375ae89641954a46718 MARCH.BAS
   99872b28ee6a976dedc16ca52e8fddf7 STARS.BAS
   eede0ef0c0ca3d45d32cb62626bd2ff5 SAKURA.BAS
   8f49e98a2402706a9f7379ced35c25a2 SCALES.BAS
   ae9b3f828835b3354fc9bf68c0ad38ab HAT.BAS
   cd934c4abaed629c3b5fedaa89848a45 CIRCLE.BAS
   36aa895f9599e28b24c962d028d73b32 PIECHART.BAS
   614ca59d96c64dad9906ba8e3648cd83 SPACE.BAS
   fd1b7820181e861becc7a821e95deec0 BALL.BAS
  caf204273d6473614b040de20b1dbf99 COMM.BAS

On our Forensic Examination page, we've also included the MD5 checksum for an image file of the whole diskette!

 

NOTE: This is still a work in progress!

 


 

Last Update: 25 September 2005 (25-09-2005).

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