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  1. Modifying an IBM 4869 external floppy box, Part 2

    Okay, now replace the cable retainer (all plastic), making sure to press firmly along its entire length to make sure that all wires have been pierced by the insulation-displacing contacts and that the retainer latches into the connector body:
    Click image for larger version. 

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    Fold the cable over the connector body as it was originally, and replace the strain relief. You may need to bend the ears slightly together to get the relief to latch over the retainer. You'll probably have ...

    Updated March 16th, 2019 at 03:07 PM by Chuck(G)

  2. Talking to an autistic Macintosh Classic

    In the VC Forum thread "AppleTalk from Mac Classic to Ethernet on iMac G3" I got a range of advice on how to get data off a Macintosh Classic with very limited software and hardware options.

    The Classic had System 7.0 installed, which did not include PC Exchange for read-write of PC floppies. Nor did this installation have any AppleTalk link active.

    The options for communication were:

    1. 8-pin min-DIN serial port
    2. DB25 SCSI port ...
  3. Cloning a PAL/HAL (Part 3)

    Part 2 of this series can be found Here

    With the hardware to read the PAL "brute force", all we need is a program to do it.

    //	Read a 10L8 PAL and come up with a truth table.
    //		Uses the little board with the 393s
    #include <stdlib.h>
    #include <stdio.h>
    #include <dos.h>
    #define PRINTER 0x378			// printer base port
    #define PAL_DATA 0x80			// bit representing the

    Updated June 12th, 2019 at 09:57 PM by Chuck(G)

  4. Cloning a HAL/PAL, Part 11

    This example details cloning the Creative Sound Blaster CT1350B U12 PAL. If you're just starting out on this thread, go to the start at Part 1.

    Okay, so we've got a weird looking PAL "brute force" dump, that has 10 inputs and 8 outputs, but it doesn't work. In particular, we've noticed that the data from dumping the dupe doesn't match the original:

    000000  A1 A9 B1 BB BB BB BB BB-A1 A9 B1 BB BB BB BB BB
    008000  A1 A9 B1 BB BB BB BB BB-E1

    Updated June 12th, 2019 at 10:22 PM by Chuck(G)

  5. Cloning a PAL/HAL, Part 13

    Part 12 of this series is here. The beginning of this series is here.

    Cloning the Trantor T130B ROM PAL, continued.

    In the preceding entry, we've discovered that simply reading and crunching the original PAL results in impossible garbage. In particular, nothing appears to be happening with the output on pin 13. So, let's pull out the datasheets and continuity tracer and see what gives.

    The controller chip on this board is an NCR 53C400. The datasheet ...

    Updated June 12th, 2019 at 10:19 PM by Chuck(G)

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