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

  1. #11

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    Quote Originally Posted by Al Kossow View Post
    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.
    The non-DMA Xebec S-100 adapter was not exactly fast, even back in the day. I managed to get equivalent performance just doing bit-fiddling on some glorified parallel ports for some systems that didn't have S-100 slots. SASI was pretty simple - SCSI added synchronous mode, disconnect, and lots of other stuff that was harder to implement in code + ports only - some sort of state machine was always a better solution. When we sold systems that needed higher performance, we used Priam drives and the ADSI (ADES, back then, before the negative connotation of that pronunciation) S-100 host adapter.

    BTW, the 1410 had a different EPROM on it for various drives. As I recall, the Syquest SQ306 used a piece of each track on the cartridge near the index for servo information (AKA servo wedge) and you would wipe that if you used the vanilla 1410 ROM and tried to format the cartridge.

  2. #12
    Join Date
    Apr 2017
    Location
    Switzerland
    Posts
    192

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    Quote Originally Posted by new_castle_j View Post
    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!
    I also happen to have a controller on my PDP-11 that interfaced with a Xebec s1410. What firmware and what settings did you use on the SCSI2SD to emulate the S1410?

  3. #13
    Join Date
    Dec 2011
    Location
    Minnesota, USA
    Posts
    223

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    Quote Originally Posted by cbscpe View Post
    I also happen to have a controller on my PDP-11 that interfaced with a Xebec s1410. What firmware and what settings did you use on the SCSI2SD to emulate the S1410?
    I worked directly with the developer and received the firmware update from him, it's not been posted for download yet. PM me if you want it, it is for the v5 scsi2sd device.

  4. #14
    Join Date
    Apr 2017
    Location
    Switzerland
    Posts
    192

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    Sent him a mail as well and got the Firmware. He plans to bring that to the official release, as soon he finds time . I'll give it a try this Weekend. The tricky thing will be probably that the SCSI2SD will report back something useful for the Plessey RL02 Controller when he does power-on selftest.

  5. #15

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    Very nice, but I thought the US is full of the original Xebec 1410 controllers?

    I really would like to experiment with those SASI 2 SD controllers as well...
    WTB: RX8E / M8357 and Case for Altair 8800

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