gary@brb.isnet.inmos.co.uk (04/13/90)
I am currently working on a hard disk controller project in my spare time, to hook a standard ST506 disk drive up to the Atari DMA port using my own microprocessor/drive controller design. Yes I realize that it has already been done :-) , but I hope to have intelligent cacheing, and the use of the processor (transputer) as a co-processor. The project originally started as a low cost way to get a hard disk drive hooked up to my ST (at the time they cost about 600 pounds) and at the same time play with a transputer. The original circuit used the DMA port in a very non-standard way and as a result was very slow. It was then a challenge to modify the circuit to use the DMA port in its proper mode to get the same performance as a bought drive. I used a logic analyser to examine the DMA port interface (oh for just a glance at the Developers Kit documentation on the DMA port :-) :-) ), and eventually worked it out. Unfortunately most ST books give only a cursory description of how to drive the DMA controller, the best I have is the Abacus book "Atari Disk Drives Inside and Out", but it still leaves a lot to be desired. Anyway, I am almost there. I can now format my drive using either the ICD or Supra software, and so use it. However my debug system tells me that some ASCI/SCSI commands are recieved which are not documented in the above mentioned book. I don't know what they do, so cannot write the code to emulate them. It would help enormously if someone could send me a list of the commands recognised by the Adaptec 4000 board (the one I am trying to emulate at present), or any other relevant information. Apologies in advance if this information is company confidential (but people clone IBM's don't they :-) in which case please inform me. Also is the extended partition format (stored in the boot sector of the drive) as used by ICD and Supra in the public domain? and if so does anybody have details of it? Presumably it is an extension of the normal boot sector as described in ADDIAO. Any pointers to further information sources will be gratefull expected, although I suspect that it is fully documented in the Developers Kit :-) BTW, does anybody in the UK know how much the Developers Kit costs? And if so how can I tell if it worth the money, after all I don't want to buy anything that I can't examine first (is this a common problem?). ============================================================================ Gary Morton Inmos Ltd, Aztec West, Bristol | EMail(UK) ----------| +44 454 616616 X520 |------------| gary@brb.isnet.inmos.co.uk The opinions above are my personal views | EMail(ROW) and may not reflect Inmos policy. | gary@brb.isnet.inmos.com ============================================================================