gferluga
Member
- Joined
- Jul 11, 2015
- Messages
- 49
Hello everyone,
I’m trying to extract files from a non-standard CP/M disk format (77 tracks), but I’m currently stuck.
The disk image comes from a Kyber Minus Z80 system, which appears to be a close twin of the Ferguson Big Board, and historically related to the Xerox 820.
Disk characteristics (as far as I can tell):
• 77 cylinders
• 2 sides
• 26 sectors per track
• 256 bytes per sector
• CP/M 2.2
• Custom BIOS / non-IBM sector mapping
I can list the directory correctly (both on the real machine and from IMD analysis), but cpmcp fails when extracting file data, even with custom diskdefs.
I’m attaching:
• KYB01.IMD – the disk image
• KYB01.jpg – photo of the real CP/M directory listing
• KYB01.TXT – output from CP/M / ImageDisk / analysis tools
Goal: extract all files from the IMD image to a modern filesystem (Windows / macOS / Linux) for preservation.
At this point I suspect:
• BIOS-specific sector mapping (even/odd track ↔ side)
• non-standard skew or block allocation
• something that cpmtools cannot handle without custom logic
Any advice, tools, scripts, or historical insight would be very welcome.
Thanks in advance!
I’m trying to extract files from a non-standard CP/M disk format (77 tracks), but I’m currently stuck.
The disk image comes from a Kyber Minus Z80 system, which appears to be a close twin of the Ferguson Big Board, and historically related to the Xerox 820.
Disk characteristics (as far as I can tell):
• 77 cylinders
• 2 sides
• 26 sectors per track
• 256 bytes per sector
• CP/M 2.2
• Custom BIOS / non-IBM sector mapping
I can list the directory correctly (both on the real machine and from IMD analysis), but cpmcp fails when extracting file data, even with custom diskdefs.
I’m attaching:
• KYB01.IMD – the disk image
• KYB01.jpg – photo of the real CP/M directory listing
• KYB01.TXT – output from CP/M / ImageDisk / analysis tools
Goal: extract all files from the IMD image to a modern filesystem (Windows / macOS / Linux) for preservation.
At this point I suspect:
• BIOS-specific sector mapping (even/odd track ↔ side)
• non-standard skew or block allocation
• something that cpmtools cannot handle without custom logic
Any advice, tools, scripts, or historical insight would be very welcome.
Thanks in advance!
