Hi,

This is far from 6502 related, infact it's more 8080 related, but I'm having trouble with the WD37C65 FDC (an NEC 765 controller clone with onboard data seperator and AT/EISA compatability).

I'm asking here because I believe this forum to be one of the better collections of old computer techies on the net.

Does anyone know the correct method to format disks? The manuals describes it but not clearly enough.

If anyone has anything which expands on the original manuals (Intel 8272A, NEC uP765 or WD37C65) I would greatly appreciate it.

I've done relavent Google searches and been through the Linux and NetBSD source codes with no luck (I'm hopeless when it comes to advanced C anyway...).

My current method is to do this. Send the Format Track command, wait for the status flag to read 'ready to receive data', sending off the four parameters for the sector, waiting for the status flag to say 'ready to send data', reading back the 7 parameters sent by the drive, and looping back to sending off the four parameters again, plus various variations of this.

This is incorrect, but I don't know what it should be.

I'm not using a sensible FDC (i.e. the WD1772) because I have had less luck with it, oddly enough, and I only have the WD1772 and NEC clones at my disposal.

Thanks heaps,

Thrashbarg

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Check out my 8080 project: http://kaput.homeunix.org

Hi,

if you have problems with the 1772, I have a (6502-based) device driver and schematics for a 6502-based system with it on
http://www.6502.org/users/andre/csa/ (schematics) and
http://www.6502.org/users/andre/osa/ (device driver)

Andre

Thanks for that, I'll give the WD1772 a go again.

Why are you using the IRQ pin indirectly? Latency in the interrupt routine?

I never thought to attach DRQ or IRQ to an input and poll them... this is what the 8080 design does to people

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Check out my 8080 project: http://kaput.homeunix.org

Sorry, I made the design about nine years ago. Will have to look more closely again. Guess I didn't need it in the driver.

Thanks a heap for that, I'm very close to getting CP/M running now

Where would you find these chips, other than in Atari and Commodore equipment, I've only got one and I would like to make a 6502 computer with it.

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Check out my 8080 project: http://kaput.homeunix.org

The WD1772 should be a generally available chip -- these chips are made by Western Digital (!!), not by Commodore, et. al. The decision to use WD1772 for the 1581 drive was for expediency, for the most part -- GCR is possible, but that's just one more thing to test and debug, especially when you can improve your bottom line by using already available, off-the-shelf, and by then far more affordable, hardware.

(Remember that when the 1541 came around, most floppy drives used bit-banging to some extent to keep costs down, especially for Apple and Commodore drives. Not sure about Atari.)

The 1571 was basically a 1541 equipped with a revised ROM and support for burst-mode and CP/M (heh, and dual sides -- it was a true 320KB drive). The 1581 was an opportune time for Commodore to provide a clean break, since you can't jam a 5 1/4" disk in a 3 1/2" hole, and hence, a significantly reduced need for backward compatibility.