MS-DOS 2.25: was it ever released or was it vaporware ?

[PorkyPiggy]

The actual BIOS (system BIOS and DOS BIOS) ROM is PR10002/PR10003, not PR10001. PR10001 is the DOS ROM plus a disk formatter. Interestingly enough, this DOS ROM actually contains disk-based MS-DOS, not ROM-based MS-DOS. The DOS BIOS copies the DOS from the DOS ROM into RAM upon taking control. This is probably why you can just pull the DOS from the DOS ROM (first 0x460B bytes) and boot it with a PC-DOS BIOS.

I have extracted all the MS-DOS 2.25 file (including MSDOS.SYS), see attachment.

Sincerely,
Pig

 

[clueless_engineer (Brett)]

The actual BIOS (system BIOS and DOS BIOS) ROM is PR10002/PR10003, not PR10001. PR10001 is the DOS ROM plus a disk formatter. Interestingly enough, this DOS ROM actually contains disk-based MS-DOS, not ROM-based MS-DOS. The DOS BIOS copies the DOS from the DOS ROM into RAM upon taking control. This is probably why you can just pull the DOS from the DOS ROM (first 0x460B bytes) and boot it with a PC-DOS BIOS.

Thanks again! My assumption about the PR10002/3 ROMs is due to the in-built diagnostics having the same version number as the ROM, so I appreciate you taking the time to actually figure it all out. I'll update my Github.

I still need to figure out the 50-pin connector so I can upload the COMMAND.COM file to the machine and see if it'll then boot.

Brett.