From: David Wood (
Date: 2004-07-06 05:01:35

You could do something like the 1541 does: Use a hardware device of some
sort to make the PET think youre going to say something (basically stalling
the bus) until the PC is ready to reply.  I'm not sure how to do this on
CBM's IEEE bus though..


On Mon, 5 Jul 2004, Baltissen, GJPAA (Ruud) wrote:

> Hallo allemaal,
> For the ???th year in a row I'm still working on my, let's say, 64HDD
> version for the PET/CBM. In general things work fine. But a big
> troubleshooter was, and still is, the handling of the DIRECTORY command.
> For those who forgot: this is the BASIC V4 version of 'LOAD "$",8' with two
> major differences:
> - the output from the drive is sent to screen, not saved as a BASIC file
> - the transfer is interrupted everey one or two bytes by te CBM for one or
> another reason
> Most of the transfer is not time critical. The only time critical is that
> you HAVE to start sending data within ??? uSecs after receiving TALK
> otherwise the computer responds with "FILE NOT FOUND". This time critical
> thing also applies to the time between bytes.
> The actual transfer of the bytes is done using handshaking, not time
> sensitive clocking as with the IEC-protocol.
> The stupid thing is that, just because of time sensitivity described above,
> everything I have to sent is placed in RAM so during a transfer IMHO most of
> the time the program is waiting for the handshake signals and checking ATN
> in between. And yet sometimes the CBM responds with a "DEVICE NOT PRESEN?"
> which means the PC hasn't noticed a ATN for some reason.
> The only thing I can think of is that a PC-interrupt consumes to much
> precious time. So I'm thinking of shutting down some interrupts in one or
> another way. Who has experience (I'm especially thinking of Nick and Andre)
> and can give me some usefull tips ?
> Many thanks IA !!!
> --
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>   / /  |_/     Groetjes, Ruud
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