Classic Computer Magazine Archive COMPUTE! ISSUE 46 / MARCH 1984 / PAGE 10

Load Errors With 64 CP/M

I have a 64 with a 1541 disk drive, and have just bought a Commodore 64 CP/M Cartridge. While making a backup copy of the CP/M System, I got a READ ERROR message. This error occurred on every attempt. I finally made a copy on my dealer's disk drive. I don't have any problem with my disk drive in loading and saving other programs.

Also, while using the Editing Command such as ED SAMPLE.TXT to create a new file, I got BDOS ERROR ON A: BAD SECTOR, no matter which disk drive was used.

Would you please answer these questions:

  1. Do I have a bad disk drive or a bad diskette of the CP/M System?
  2. I intend to add a second 1541 disk drive instead of using a CBM 4040 dual disk drive. Will CP/M recognize them as Drive A & B?
  3. Do I have to specify the computer and disk drive I use when ordering a COBOL Compiler?

W. P. Ling

  1. This sounds like an alignment problem. If your 1541 is only slightly out of alignment, you may still be able to access most files without getting read or write errors. Alignment problems are more likely to show up when the drive accesses the innermost and outermost tracks of the disk. This is because the read/write head is at the limits of its range, and CP/M stores its system files on tracks 1 and 2, the outermost tracks. Since the system files are accessed frequently, correct alignment is critical if CP/M is to operate properly.
  2. On the 4040, the drives are designated drive 0 and drive 1, which CP/M recognizes as drives A and B. However, if you connect two 1541 disk drives to your 64, both are designated as drive 0, with different device numbers (usually 8 and 9). Since CP/M looks at the drive number and not the device number to find drive A or B, it will not accept the second 1541 as drive B.
  3. Yes. However, we know of no COBOL compilers currently available which operate under CP/M for the 64.