BUG REPORT: OpenCB; <--> Zoomfloppy <--> parallel cable issue

[Thomas Winkler]

Hi 

It seems there is a small bug in communication code maybe ...

I have modified the drive code of TRANSLIB in OpenCBM while workinf on MEMCOPY.

My main drive Code is located at $500 (buffer 2) and Trans-Code is at $700.
Tis main drive Code is waiting for commands from PC:

- send byte

- send 2 byte

- send 256 bytes
- send test pattern

- ...

So Main Code waits for command and depending on command it sends bytes back using Trans Code at $700.

This working fine for S1.

This working fine for S2.

This doesn't work fine for PARALLEL.

Parallel Code has problems on changing direction of data flow.

You can send a megabyte of data without problems.

But always if direction was changed the first byte sent to PC is zero!

I was wondering  about, D64COPY works fine with parallel trans Code.

I find out, parallel transport always send 2 bytes.

While sending 1 byte the second byte is ignored in this protocoll.

I also saw, sending 1 byte always works fine!

D64COPY does send 1 status byte followed by 256 data baytes.

So this is the reason why D64COPY works fine.

But sending 2 Bytes or 256 Bytes or 1024 bytes, always the first byte goes wrong after a change of direction.

I have made waitstates of 20ms on PC side.

But this makes no difference, first byte goes wrong, always.

best regards

Tommy

[Nate Lawson]

Do you think this is specific to the ZF or OpenCBM on other adapters? I don’t think I’ve looked into reversing direction in the d64copy parallel case, and this might be broken for the xu1541 also since that code largely came from there.

-Nate

> --
> You received this message because you are subscribed to the Google Groups "ZoomFloppy Users" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to zoomfloppy-use...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/zoomfloppy-users/70f5fb47-afac-4f22-8b0e-f03007541213n%40googlegroups.com.

[Thomas Winkler]

Hi Nate

I'm sorry, I don't have any other adapter working than Zoomfloppy. My XAP-1541 makes no sense since none of my PC has a parallel LPT port.

But I think it is only solvable in Zoomfloppy, cause I use this USB plugin calls (same as D64COPY does):

  opencbm_plugin_pp_dc_write_n(__fd_cbm, data, size);

  opencbm_plugin_pp_dc_read_n(__fd_cbm, data, size);

The problem only occurs on the FIRST "read" after a "write".
All following call to "read" working perfectly.

And it is only the first byte which fails, and content always is 0.

Best regards
Tommy

To view this discussion on the web visit https://groups.google.com/d/msgid/zoomfloppy-users/460CFAFF-FD0E-4B3D-ADFB-11A660DF7E37%40root.org.