SCSI to IDE - test-drb@ccmp.vtda.org

3 Dec 2010

SCSI to IDE

Joachim Thiemann joachim.thiemann
<mailto:cctalk%40classiccmp.org?Subject=Re%3A%20SCSI%20to%20IDE&In-Reply-To=
%3CAANLkTikac5TkJkKANRBy_tH4rvEUZPE0qfBfS%3DouSuJN%40mail.gmail.com%3E> at
gmail.com 
Sat Nov 27 09:07:00 CST 2010 

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  _____  

On Fri, Nov 26, 2010 at 11:48, joe lobocki <jlobocki at gmail.com
<http://www.classiccmp.org/mailman/listinfo/cctalk> > wrote:

...
  So what is our option? I have seen SCSI to IDE
adapters around, but they go

...
  up into the $100's to $200's, say you have a
minimum 10 machines, that 
...
  leaves you somewhere between $1,000 and $2,000 total,
before the disk or 
...
  devices. If we could design a simple SCSI to IDE
interface, we could be set

...
  for a good long while on storage for these devices for
a decent amount of 
...
  time. There are all sorts of adapters to IDE, there is
CF to IDE, SD to 
...
  IDE, 
...
  SD to CF which could be placed in a CF to IDE adapter
if need be, i'm sure 
...
  one could also rig up a USB drive to SCSI if one
tried, but I could be 
...
  wrong. 
...

...

I have previously proposed here a SCSI-to-SD interface; I've only done

preliminary brainstorming on it, but think it should not be too hard.  The

SD card interface is very simple, both from a logic and electrical point of

view: if you don't care much about speed it can be done with SPI. (the speed

should be sufficient to keep up with 68k Mac, Amiga and Atari)  All logic

can probably be done in a single AVR or even PIC chip, if you run that at

3.3V, the only additional hardware is the SCSI level shifters.

I do not know enough about low-level SCSI to start designing this yet, and

since I gave away my Amiga 3000 and classic Macs my interest in this project

has all but disappeared... still it'd be kinda fun, I think.

Joe.

-- 

Joachim Thiemann :: http://www.tsp.ece.mcgill.ca/~jthiem

-----REPLY-----

There was some room left on my SCSI to IDE converter board design so I added
an SD socket.  
The SD circuit is very simple and is able to work with some left over inputs
and outputs from the UART.
I think this design would allow for a SCSI to SD converter as you mentioned.

The original intent was for SCSI to IDE converter but would also allow for
SCSI to CF via an IDE to CF adapter.
After a closer reading of the Z53C80 datasheet, I think it is possible to
implement both the polling mode and
a pseudo-DMA mode SCSI.  The circuitry seems pretty straight forward and I
think an 8 MHz Z80 should be
able to get some fairly decent transfer speeds.
http://www.vintage-computer.com/vcforum/showthread.php?22906-SCSI-1-to-from-
IDE-drive-converter
Andrew Lynch