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    NOVA 4/X Restoration

    When I was working at AEDC in 79-81, we had a spectrometer with a Nova. The boot had to be toggled in manually. I couldn't do that, because that was a union job. I also found out that turning on its vacuum pump was a union job (I got written up).
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    What software is good for creating waveform timing diagrams?

    Years ago (late 1980's) I was using PALASM to generate some PALs. I got tired of reading the output states. So I wrote a program in Turbo Pascal to display the state outputs similar to a Logic Analyzer.
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    PS/2 interface, was the kb and mouse on same or different data/clk?

    I worked on IBM's 3890/XP check sorter, that could sort 40 checks/seconds, and when running would get 120 interrupts/second. The operating system was OS/2 (1.3,2.1,4.0) running on various PS/2 machines. If there was a mouse attached, and you moved the mouse around while sorting, some interrupts...
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    I have become obsessed with vintage printers.

    I worked at IBM on the 4214 printer (among many others). It was a Centronics mechanism, with one of two interface cards(coax-3270 or twinax- S36/S38) provided by IBM. The coax printer was available with monochrome or color, the color being for the European market. This business kept...
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    Unknown 68k Board

    One (maybe) interesting thing about the 3812 (and 3816) diskette. It didn't have a directory. You had to read the header of each file before you got the right one. The header had the length of the file, so you knew where to go for the next file. It's not a FAT diskette.
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    IBM 524x Printer Emulation

    I just saw the comment about the mechanisms being shared with other printers. There were several printers that had similar mechanisms (5241,5242,4974,4975,5256,3287, maybe more). Although the mechanisms were similar, there were a fair number of mechanical differences. Even the processors used...
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    IBM 524x Printer Emulation

    I worked on the code in the 5242. The first thing I was assigned was to fix what was called "the sleepy printer problem". Now and then, the printer would just stop, with the stepper motor controlling the paper advance locked. There had been several previous attempts to fix it, but they all...
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    Unknown 68k Board

    IBM didn't make the 3812. It was built by an outside vendor. It was a LED printer, not a laser printer. IBM got sued by some guy who had a patent on a 2 row LED printhead. The 3812 had a one row LED, but the SELFOC lens looked like two rows, and lost the suit. I was tasked with putting a...
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    Which minicomputer architectures used "skips" to branch and had no stack?

    I don't think so. It was developed in Boca Raton, and the assembler ran on MVS and VM. There were 2 used in the printers. One for control, and the other for the Head Image Generator. It was a 4 bit processor with a 12 bit address bus, bank switched to access different memory cards. It was...
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    Which minicomputer architectures used "skips" to branch and had no stack?

    I used the IBM ATOM (A Tiny Optimized Microcontroller) in the IBM 5224 and 5225 printers. It had a 2 level call stack. If your subroutines went more than two levels, you were toast. When I started working on this, this guy showed me this "great debug tool" (his words). You connected it to...
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