Finally, some luck on Heath soft-sector CP/M format

HxC Floppy emulator support for all others computers...
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snhirsch
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Joined: Tue Dec 08, 2015 1:42 am

Finally, some luck on Heath soft-sector CP/M format

Post by snhirsch »

After a large amount of aggravation, I'm getting somewhere with this. It will not be a surprise to the HxC developers to hear that it was the Gap 3 setting. Looks like the IMD image needs to be exported as XML and edited to make Gap 3 different, then converted to HFE.

Update: Spoke too soon. I'm getting very intermittent behavior. Copying the full capacity of files to the emulator works about 1/2 the time and the other 1/2 is random write errors. Even with a full write that works, reading files off the emulator fails about 1 in 4 times. I've tried pushing Gap 3 one way, then the other, but there is no apparent correlation with the intermittent behavior. It simply stops working at all if I go too far either way. If time permits, I'm going to watch the bus with a logic analyzer and see if there are any gross differences between the emulator and a real diskette drive.

Update #2: Logic analyzer trace shows no smoking gun. There are 0x4E gap bytes on both sides of the index as I'd expect. It does not look like the sector data is wrapping over index. The timing and pulse width on the RD DATA line is a little odd and does not look much like what comes off a real floppy. The pulses are about 1/4 the width of a real diskette and not as regularly spaced.

With Gap 3 set at 66 (recommended value for the WD 17xx controller in the H89) I'm able to boot a single-sided image and read it without error. Writes to that same disk image are still highly intermittent, with about 4 of 5 attempts throwing sector errors at some point. Only occasionally does it succeed in filling the diskette. It's possible this Gotek hardware is defective or out of spec, so I'm going to buy another bootloader and try another unit here.

Would really help to get a response from one of the developers, but I guess everyone is busy with the Holidays.

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