Difference between revisions of "Disc format"

Revision as of 11:52, 21 February 2019

CPCs could read discs formatted in three separate ways. Several high-capacity disc operating systems existed to add new formats to the three standard ones.

Standard CPC disc formats

• Data: 180k single-sided. 40 tracks of nine 512-byte sectors each. Sectors numbered &C1 to &C9. 64 directory entries. Can also be read by PCWs. The useable capacity is 178k.
• System: 180k single-sided. 40 tracks of nine 512-byte sectors each. Sectors numbered &41 to &49. 64 directory entries. Two reserved tracks containing CP/M BIOS. The useable capacity is 169k.
• IBM: 160k single-sided. 40 tracks of eight 512-byte sectors each. Sectors numbered &01 to &08. Provided for compatibility with CP/M-86 (and DR-DOS 1.0). Used by very few CPC purchasers, but Locomotive Software stated that this was invaluable for cross-assembly. The useable capacity is 158k.
• Vendor: Term used for System format discs with no software in the reserved tracks. The useable capacity is 169k.

All these disc formats use a CP/M based filesystem.

Third-party CPC disc formats

• FAT formats [1] (invented by MS-DOS; supported by SymbOS, DOS Copy, ReadDSK, DSK-CPC)
• MS800 formats
• Prem format (supported by Stream2)
• RODOS formats
• ROMDOS formats (also supported by ParaDOS: D80 supported by S-DOS and 400K/S)
• Ultraform
• Vortex (80 tracks, 2 sides, 9 sectors of 512 bytes, 2 reserved tracks, 704 KB; supported by FutureOS and XD-DOS)
• Xexor formats (also supported by ParaDOS)
• XD-DOS (supports 0.7 MB Data-, System- and Vortex- formats)
• etc.??

References

• http://www.seasip.info/Cpm/amsform.html
• http://www.wacci.org.uk/magazine/138/138_08.html
• http://www.microsoft.com/whdc/system/platform/firmware/fatgen.mspx