From: Daniel Kahlin (tlr_at_stacken.kth.se)
Date: 2005-10-03 17:34:44
On Mon, 3 Oct 2005, Groepaz wrote:
> On Monday 03 October 2005 16:11, Baltissen, GJPAA (Ruud) wrote:
>> Hallo Patryk,
>>
>>> I am not sure if I am missing something very obvious but I
>>> just don't understand WTH is the EOR $1801 for and ....
>>
>> It won't help you but at least it gives you the feeling you don't stand
>> alone: I don't understand it either. IMHO the EOR should indeed fill A with
>> zero after the EOR.
>
> mmmh i know little about drive coding, but isnt $1801 an i/o port which thus
> might have changed in between the two instructions?
Yes. Like stated $1801 is the parallel port. This is the write routine
of a parallel-cable nibbler, yes?
What does the other end look like? (the c64 code)
The code you posted looks something like this if made into a single
loop. (original does this twice every loop)
0. lastdata=0
1. Do difference between last parallel-data and current
2. queue for writing to disk.
3. Ack.
4. Read parallel-data to lastdata
5. wait for write to finish. (bvc *)
6. goto 1
/Daniel
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