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Re: Apple floppy adaptor. I'm stuck!
Michael J. Mahon wrote:
> Michael J. Mahon wrote:
>> Tristan Mumford wrote:
>>
>>> G'day.
>>>
>>> As you may or may not know I've been working on a little device to
>>> allow PC
>>> 3-1/2" floppy drives to be used on a disk ][.
>>>
>>> It can now do the following:
>>>
>>> * de/Select and spin up/down the drive.
>>> * Detect the write-protect state of an inserted floppy.
>>> * Move the head around.
>>>
>>> What it can't seem to do is read and write. The basic question I want
>>> to ask
>>> is whether the apple2 has an active high or low for read and write
>>> pulses.
>>> I believe it's active high, but I'm starting to doubt myself a little.
>>
>>
>> Actually, it's *neither*! The Disk ][ Controller *toggles* the state
>> of the write line each time that it writes a "1". No toggle = "0".
So are you saying instead of the PC floppy dataline pulsing the data low for
a phase change, the disk ii analog card just changes state and stays that
way until the next phase change?
>
> In addition to the WRITE DATA signal, there is a /WRITE REQUEST line
> (pin 10) that is active low.
>
> I'm sure you've already sorted this, but the write protect switch is
> connected in a very interesting way in a Disk ][ drive. ;-) If phase 1
> is high, then a drive *always* appears to be write protected. (I don't
> think that any Apple software depends on this.)
Yeah all done. Hopefully correctly. Seems to be according to a combination
of UTA2, various diskII pinouts, pc floppy pinouts, and a datasheet for a
PC floppy drive I managed to dredge up.
I do have some doubts on the hex inverter I'm using to keep up with the
datarate though. It's about 20 years old. So I might pinch one from a 386
motherboard I've been stripping for parts.
-snip-
Thanks for your input!
Tristan.
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