ACSI/DMA to SCSI Adapter

[DominoTree]

So, while I'm waiting on the last batch of parts to (finally!) wrap up my external floppy adapter and start making everything available, I had some spare time and I've started working with an old ACSI to SCSI adapter schematic that I found. Right now I'm mostly-copying it into KiCad, and I've added a parity generator to improve drive compatibility somewhat, and I'll be making improvements as I progress and do testing. Ideally I'd like it to work "transparently" with existing drivers.

My goal is to fashion a PCB that can be dropped into a Megafile enclosure and used with SCSI drives which are still fairly easy to get instead of the impossible-to-find-reliable RLL/MFM drives. I think I should be able to make this work for anything pre-LVD SCSI.

If I get it all working, I'm considering using an FPGA or CPLD to implement the same thing (and perhaps more), just because I have zero experience working with them and I'd really like to learn. One thing at a time though. Schematics and board layouts. Focus. :D

Any suggestions or insight or comments are *very* welcome. I'll probably even read insults if people send them :lol:

(also if there's a better spot for me to post this sort of stuff, please let me know - I've got a couple other ideas in the pipeline for our trusty STs as well)

Screenshot from 2021-01-16 14-17-42.png

[exxos]

Cool. If you look in the docs section theres schematics for hard drive circuits.

[DominoTree]

I *think* this should work. Now to lay out a PCB - halfway tempted to just let the autorouter run and see if I end up with a functioning batch of boards before I route everything nicely by hand :lol:

Screenshot from 2021-01-18 15-13-31.png

[exxos]

I *think* this should work. Now to lay out a PCB - halfway tempted to just let the autorouter run and see if I end up with a functioning batch of boards before I route everything nicely by hand :lol:

But the autouter cant be trusted and probably make it worse, so hand route it :chairsmack: :lol:

[Steve]

It would be *very* cool if it could be small enough to plug directly on to the ASCI port and convert directly to a SCSI port. A little 'in between' adapter. It would be a lot more useful than something that goes inside a Megafile to convert into a 50pin ribbon cable (which is what you're planning I think) Of course the technology can be used either way, but not many people have a Megafile. If you make it an external ASCI>SCSI cable converter you'd be able to buy cheap old low-cost SCSI enclosures and peripherals for the Atari. I think that would be quite popular.

[czietz]

It would be cool if it supported the extended ICD command set so that drives larger than 1 GB could be used.

[DominoTree]

It would be *very* cool if it could be small enough to plug directly on to the ASCI port and convert directly to a SCSI port. A little 'in between' adapter. It would be a lot more useful than something that goes inside a Megafile to convert into a 50pin ribbon cable (which is what you're planning I think) Of course the technology can be used either way, but not many people have a Megafile. If you make it an external ASCI>SCSI cable converter you'd be able to buy cheap old low-cost SCSI enclosures and peripherals for the Atari. I think that would be quite popular.

I love it! Kinda in the form factor of the ICD Link 2 maybe?

[DominoTree]

It would be cool if it supported the extended ICD command set so that drives larger than 1 GB could be used.

Right now it's just "dumb" digital logic stuff but that's definitely something I want to explore once I get this revision working properly

[beel1]

I think the amazing work Wolfgang Foerster did on his ACSI-SCSI bridge could be of great help ;)
https://shop.inventronik.de/index.php?i ... &id_lang=1
It handles ICD protocol since version 2K12A

The sources are available from http://www.experiment-s.de/de/download/ under LGPL:
https://download.experiment-s.de/Config ... tl/vhdl.7z

Different backends are here:
https://download.experiment-s.de/Config ... I_Adapter/
https://download.experiment-s.de/Config ... I-Adapter/
https://download.experiment-s.de/Config ... ACSI_SCSI/

[Tomswork]

I give the wolf gang asci to scsi an a plus had to make a cable to use on mega ste and I use it with a scsi2sd

Tom