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Thread: Gorgeous Floppy Disk Controller PCB - SMS model FD0303 for IBM 3740 PERTEC FD400

  1. #1
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    Smile Gorgeous Floppy Disk Controller PCB - SMS model FD0303 for IBM 3740 PERTEC FD400

    Hi all,

    As I was getting out my Floppy Drive alignment Disks, I had the early Floppy Disk Controller card stored with them.

    I had partly forgotten about it so I brought it up to the house and last night I sat and read the brief manual that accompanied it.

    Just took the photos and wanted to share them.

    Visually it quite beautiful and brand new.

    On reading the manual and looking at the PCB I note it has Pertec Control ROMS fitted, and I read further this
    means its suits PERTEC FD400/511 Floppy Drives.

    Well I think all my spare 8" drives are not Pertec, so I wonder if I can find copies or the ROMS for this SMS FD0303 to suit Shugart or CDC










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    Typical 8X300 bipolar controller. ROMs are all bipolar. It's a power hog.

    But you can probably drive a SA800-type drive with a little external logic to handle the step peculiarities. (The FD400 uses two lines, step in and step out, to move the head; the SA800 uses a STEP signal and DIRECTION to specify which way to step.) All the other signals should be pretty much the same.

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    8X300? Can't be, that has 50 pins, the board chip has 48, also no 8T32 etc I/O ports.

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    Quote Originally Posted by woodchips View Post
    8X300? Can't be, that has 50 pins, the board chip has 48, also no 8T32 etc I/O ports.
    MC555D 'interpreter' which became the 8X300
    http://bitsavers.org/pdf/sms/microco...ption_1975.pdf
    http://bitsavers.org/pdf/sms/brochur...hure_Sep76.pdf

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    The TO-5 external transistor is the clue. It was part of the on-chip voltage regulator. The thing is part of the 8x300 family.

    There was a peripheral chip, 8x330, that was made to interface to the 8x300/305 that was a floppy controller, but I don't see it here.
    Last edited by Chuck(G); June 8th, 2019 at 08:00 AM.

  6. #6

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    One lives and learns!

    Was the 8X300 that great for it to be developed? Suppose less chips than a 74181, but even so. The 70's were a time of great experimentation, look at the various spectrum analysers around then, pity B&K can't provide service information.

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    The 8x300 could probably be categorized as a true RISC--8 instructions in the basic unit, although the set could be extended somewhat by adding other support chips. For a time, it was pretty much the only CPU that could meet the speed demands of a Winchester drive, without going to a pile of MSI TTL (I have one such controller board for an SA4000 drive--it's the same physical footprint as the drive.). MOS still had a long way to go. The only other real alternative was bipolar bit-slice (e.g. Intel 3000 or AMD 2901).

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