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Re: Apple floppy adaptor. I'm stuck!
Michael J. Mahon wrote:
> Tristan Mumford wrote:
-snip-
>> 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?
>
> The WRITE DATA line stays whichever way it is until the next "1" (which
> is the next flux reversal).
Interesting that after the uC bombed out and it was forced to look at where
it had formatted that it could read the signals it laid out. I guess it
kind of makes a sort of vague sense that if it wrote using the wrong signal
it would interpret the read the same way.
I'll have to see what happens after I get my hands on another 16f628a, now
that I've supposedly fixed the head stepping problem.
The read / write incompatibility will probably cause awful problems, but I
am curious as to how bad the problem will be.
>
> (I find using "phase" in this context confusing, since the head stepper
> is positioned using "phase" signals.)
Agreed. Sorry.
>
>>>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.
>
> Any LS part shouldn't have any difficulty with the 250kHz data rate,
> consisting of 1usec pulses. 50ns is a long time for these parts.
You vastly overestimate me and my components. I quote from the IC "DM7414N"
Sure it's a schottky at least.
>
>> Thanks for your input!
>
> You're welcome, and I hope it all works for you!
Me too. Really I do.
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