X68000 internal SASI pinout

Started by Computolio, July 09, 2007, 03:36:01 PM

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I can't seem to find the pinout of the 20-pin internal SASI connector used on the X68000. I'm trying to build an internal cable so I can attempt to hook up a SCSI drive. I know many of the SASI drives that shipped with X68000 machines had 50-pin connectors, and I've heard success stories of people getting SCSI drives to work using special drivers, so instructions on building this cable have to exist somewhere.

   Could I just trace it out using the external 50-pin connector on the back of the machine? Does it conform to the SCSI pinout?


Hrm, the only pinout I have is from the XVI, which uses SCSI instead of SASI.  All my schematics are for the XVI as well.  =/

The HDD port is controlled by the I/O controller chip.  Like most of the custom chips in the X68000 series, the I/O chip went through many revisions.  Called Sicilian in the first X68000, it was the IOSC in the ACE, IOSC-2 in the Pro, Pro 2, Expert and Expert 2, and Pedec in the Super and XVI.

Sicilian and its successors handled all the HDD IO as well as the floppy drive extra features like eject, drive select, LED blink etc.

Like SCSI, the SASI port had an 8-bit data bus.  The other signals present are /MSG, C/D, I/O, /BUSY, /REQ, /RESET, /SEL and /ACK.

That's all I have for now.  I'll see if I can find more pinout stuff.


I figured that that was how the SASI interface worked, as the SASI-based models don't have a dedicated controller chip like the later machines do. Something like that "SxSI" driver must only be possible if most of the work is done in software.

  I took another crack at finding the pinout on Google and I still found nothing. I still don't get why nobody has the pinout for the thing. Should I just assume that the external HD connector has a SCSI-compatible pinout and trace things from there?


The pinout should be largely compatible, yes.  In fact, I'd bet on it being the same.  It kills me I didn't keep any of the books for any X68 but my own XVIs.  =/


I traced it out and here's what I found:


   I'm not sure why the "????" pin didn't go anywhere on the SCSI connector. Maybe it's for the drive light?