(Fwd) Re: cbm 9060/9090 scsi command set

From: Ruud_at_Baltissen.org
Date: Thu, 14 Nov 2013 16:10:11 +0100
Message-ID: <5284E7D3.19397.1CF2D7E@Ruud.Baltissen.org>
Hallo Didier,

> does anybody has an idea about the command set really issued by
> the commodore controller to the scsi hard disk ?

I'm afraid I have some disapointments for you.
- There isn't a SCSI hard disk on board, it is a MFM one.
- Between the Commodore controller and this MFM hard disk sits a 
SASI - MFM converter. It is full of unknown ICs. OK, unknown to me, 
but those amongst us who know me well, can confirm I have a good 
knowledge on this area. I had once five systems to repair. I only 
managed one to revive because I only had one functioning converter.
- The Commodore controller has a SASI interface, not a SCSI one. A 
German friend of mine said that SASI was the predecessor of SCSI so 
one should be able to attach a SCSI hard disk. So far he hasn't 
- Documentation about SASI is rare. One source is:


- MichaƂ pointed me to a PDF as well, you can download it from my 
sit, please see:


- The third and last source is a Thesis written by Dutch students. 
Quite informing but.... written in Dutch. Available on request.
- I tried to make an interface to the LPT port of a PC with he idea 
that the PC could emulate the SASI board. But then my C= controller 
board brooke down :(

On the positive site:
- I made a disassembly of the ROM of Disk Controller, freely 
- This board does NOT use the 6530, the ROM is an EPROM in this 
case. The idea with the LPT interface was to gain knowledge. If 
aquired, I could replace the interface with a micro controller. But 
a second solution could be to replace the EPROM by one with my own 
content; not having to use this weird SASI protocol, it would 
simplify the interfacing. 

I hope this helped a bit :)

Kind regards / Met vriendelijke groet, Ruud Baltissen

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Received on 2013-11-14 16:00:06

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