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Thread: Xebec S100 SASI Host interface... Who has one? Any documentation? Any pictures?

  1. #1

    Question Xebec S100 SASI Host interface... Who has one? Any documentation? Any pictures?

    It seems Xebec made an S100 sasi controller by themselves...
    We were figuring out the software for the byte article and also there are errors...
    Freek Heite mentioned the existence of original Xebec software for their S100 SASI interfase.

    xebec1410cpmdrivers.zip

    According the documents the Xebec S100 controller was not able to boot.
    The example schematics in the S1410 documentation just show a simple
    host interface. I guess this should come very close to the Xebec S100 SASI board.
    Xebec voorschrift.jpg
    I really would love to see a picture or documentation of that particular board.


    At this moment I have the PCB's for the Byte HCA S100 SASI host controller in production.
    http://www.vcfed.org/forum/showthrea...059#post464059

    This PCB from the Byte article is able to boot because there is an EPROM on it.
    I Think I've recovered all errors from the Byte article. The unit from that article is
    based on the Xebec example circuit. That was very useful to find errors...
    The original Xebec software will probably help a lot too. Because the Byte article
    contains many errors and isn't quite complete...

    But I think it is very interesting to see the Xebec S100 host interface! Does anyone have it?
    Is there any documentation? Any pictures?

    Regards, Roland
    Last edited by Roland Huisman; June 22nd, 2017 at 12:47 PM.
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

  2. #2
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    SASI tends to be a very simple SCSI-1 interface, no?
    Last edited by Chuck(G); June 22nd, 2017 at 01:27 PM.

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    there is a seriously mangled ocr of the manual here

    https://amaus.net/static/S100/softwa...SCSI/S100SCSI/


    also, this is the same board that DTC sold as the DTC-10 (or DTC-10-1 with DMA)
    DTC-10-1_S-100_SASI_DMA_Adapter_Preliminary_Specification_Apr 81.pdf on bitsavers has a schematic

    I've got a board around somewhere I'll see if I can take a picture of it.
    The same was true between DTC and Xebec for the Multibus host adapters.
    Last edited by Al Kossow; June 22nd, 2017 at 02:00 PM.

  4. #4

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    Thanks! The D10-1 schematic is completely different from the Xebec example schematic.

    Which one do you have? The DTS-10 or DTS-10-1? Very curious!

    Regards, Roland
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

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    Roland,
    I think I found an Xebec SASI controller for the S-100 in my collection. Up until now I did not know what it was, but reading this thread caused me to dig it out again and do some research. Here is a photo from the Xebec brochure on bitsavers (http://www.bitsavers.org/pdf/xebec/b...chure_1984.pdf)

    xebec.jpg

    and here is a photo of my board, which has no brand name on it at all, it's simply labeled S100 Host adapter:

    IMG_1777.jpg
    Attached Images Attached Images

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    I found a copy of the manual for this board in Rlee Peters archive!! It was riddled with odd characters and goofy spacing (I think it was an OCR capture), but I have cleaned it up and it's now readable with MS Wordpad (other txt editors skew the text alignment, don't know why). Anyways, here it is.

    S100SASI.TXT

  7. #7

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    Great! Thanks for the picture! That is more like what I expected. The PCB seems to
    have some extra possibilities. Probably they used the same PCB for differed versions?

    I really have to go further with my HCA project...
    It has been waiting since other project came across...

    http://www.vcfed.org/forum/showthrea...344#post472344
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

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    Just making a follow up post here, yesterday I finally found success in making my Xebec s100 SASI card work! It was quite an adventure, but very satisfying to see it in action. This was a board that I previously did not know what it was for until Roland posted an inquiry here and the gears in my head started moving. This card was sold by Xebec and was meant to be paired with their s1410 SASI to MFM bridge board. In my case I did not have a s1410 to play with, so I acquired a SCSI2SD device shown here: https://store.inertialcomputing.com/...csi2sd-v5b.htm
    A firmware update from the developer causes it to emulate the s1410 and data storage happens on a mini SD card. I had problems running the SASI card with an 8Mhz z80, but after switching to 6Mhz, everything is working! I'm curious if other SASI boards would require different code to run or if SASI implementations are mostly vanilla. Anyways, this forum helped make another success story!

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    Quote Originally Posted by new_castle_j View Post
    if SASI implementations are mostly vanilla.
    SASI (Xebec, DTC, SMS) and early SCSI (like the Adaptec 4000) bridge boards have differing command sets.

    Some of the earliest ones required you to specify the drive's Head,Track when they were powered up, for example,
    some stored the information on the front of the disk. SCSI eventually came up with a "Common Command Set"
    that most of the embedded SCSI drives use, but those can return unique mode sense pages, the most common
    difference is the drive type and geometry returned.

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    One of the SMS controllers that I used (the RLL-to-SCSI one) didn't support much of the SCSI command set other than read, write and format. ISTR that the way you got the drive geometry was to read the sector buffer after boot.

    Early SCSI was ? fun...

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