Parallel printing through z80 PIO chip

[malfer]

I have a Mimi 801 Z80 computer which has a number of issues including not being able to load cp/m. It will however load th monitor program which permits access to directly enter code. This allows me to read sectors off floppy disc and other things. I would like to be able to read data from a disc and output it to a parallel printer using the on board pio chip. The pio ports are channel data port A is port 4, channel data port B is port 5, control port A is port 6, and control port B is port 7.
I have tried copying from cp/m what I believe to be the pio initialisation routine and sending data to the printer but nothing happens. my understanding of ports and pio is very limited although i am quite happy with z80 assembly language. Any suggestions or help would be much appreciated

 

[tom.storey]

If you show us what you have tried (code, monitor commands etc) then perhaps someone can point out what you are doing wrong.

 

[norwestrzh]

Hi Malfer,

If you can find a copy of the paperback book "Z80 Applications", by James Coffron, chapter 8 has very specific information about the Z80 PIO, including initialization code samples. There are sections for all four modes of the PIO (output, input, bi-directional, and non-handshake (mode 3)). I think you would be able to find specific help with PIO applications. The trick will be finding that book (C) 1983(!).

I'd offer to scan it for you, but it's about 30 pages!

Roger

 

[Chuck(G)]

There's also the Zilog reference manual http://bitsavers.org/components/zilog/z80/UM008101-0601_Z80_CPU_Peripherals_Users_Manual_2001.pdf PDF page 195 for PIO.

 

[pbirkel@gmail.com]

I'd offer to scan it for you, but it's about 30 pages!

See: https://datassette.s3.us-west-004.backblazeb2.com/livros/z80_applications.pdf

 

[daver2]

Yep, show us your code...

Dave

 

[malfer]

Yep, show us your code...

Dave

The routine i have used is attached below. It is quite short as i have to key it in each time I try. The main part of the routine are what I copied from the cp/m BIOS of the computer. The initialisation part does appear to do something because the print head moves and the printer goes on line but then just hangs.
Thanks for your interest.
Regards Malcolm

 

[malfer]

There's also the Zilog reference manual http://bitsavers.org/components/zilog/z80/UM008101-0601_Z80_CPU_Peripherals_Users_Manual_2001.pdf PDF page 195 for PIO.

Thanks Chuck I have looked at this but I still don't understand exactly what codes I should be sending to the ports.
Malcolm

 

[cjs]

If you can find a copy of the paperback book "Z80 Applications", by James Coffron...

See: https://datassette.s3.us-west-004.backblazeb2.com/livros/z80_applications.pdf

This is now uploaded and OCRed on archive.org as well, now.