Differences in IEEE timing?

[carlsson]

I have a Corvus hard disk setup, originally intended for the CBM 8032 series computers. It consists of a Corvus hard disk unit (available in sizes 6, 10, 20 MB - mine is 6 MB) and a Hardbox which is the IEEE-488 interface between the computer and the drive. It works very well on CBM 8032 and even 4032 although of course programs formatted for 80 columns won't run.

However, I've tried to hook it up to several CBM 610 and 710 systems, and the built-in commands like CATALOG D0 freezes the computer. If I load the directory manually with LOAD"$",8 it fetches from the hard disk as expected.

It makes me wonder - does the CBM-II line have a different or more exact form of timing than the older PET/CBM machines have? I suppose Commodore's own floppy and hard drives were designed perfectly according to the spec, while 3rd party IEEE devices may be slightly more sloppy. My idea is that a 4032/8032 would have patience to wait for the data slightly longer than a 610/710 would, but it is just a guess based on my actual experiences. Then again it suggests the implementation of CATALOG is different from LOAD.

Has anyone else seen something similar? How about the MSD floppy drives, do they connect to IEEE and work just as well with both PET and CBM-II computers, using the higher-level commands?

The reason I'm asking is that I'm trying to backup the hard disk to PC, using C2N232 and cbmlink. I have found the PETs are a bit shaky with C2N232 but CBM-II which normally doesn't use the cassette port is more solid. However while I can read a 8250 floppy drive using cbmlink, trying to access the Corvus hard drive results in lock-ups.

Probably I will need to make the backup a two-part process: first find a decent file copy program (PET or CBM-II) that can copy files from the current partition on the Corvus drive to a floppy disk - ideally 8250 format so I can fit 1 MB onto them. Then I'll transfer disk images using cbmlink. Hopefully there already is some Basic based backup software on the hard disk that I can use.

[Michau]

I find it weird that CATALOG behaves differently than LOAD "$". They should do the same. This make me suspicious that maybe the BASIC implementation of CATALOG is at fault, not the kernal IEEE timing. Especially because it hangs, not timeouts. Perhaps the hard drive sends the direcgtory in some slightly incompatible format that confuses the BASIC command.