• The Gotek

    Alexander R Pruss • an hour ago • 0 comments

    I've always been worried about aging magnetic media. Late last year, my faithful oscilloscope didn't boot up. Fortunately, I had multiple copies of the system discs (the OS lets you make copies of a disc), so I was able to get it back up, and I made a new copy. But I was worried. I finally got a Gotek to replace the aging Sony MP-F52W-30 drive, made an adapter to interface the HP's Sony-compatible cable with the Gotek (there are some instructions here and more details here). Getting the disc change connection working was the hardest. It turns out that while my SFRKC30.AT3 Gotek looks from a distance like an SFRKC30.AT2 Gotek, it exposes the PA14 pin in the same place as the older SFRC922, and so on the AT3 one should follow the older unit's instructions.

    I was now able to use HFE files (which are a complicated file format that handles all sorts of non-standard discs) on a flash drive to boot the oscilloscope. Yay! To this day (January 17, 2027), I still haven't been able to get direct image files to work, though.

  • The beginning

    Alexander R Pruss • an hour ago • 0 comments

    About a decade ago, I saw an HP 1653B Oscilloscope and Logic Analyzer on Craigslist for $50, including probes, pods, diskettes and three volumes of manuals. I was going to buy it, but when the seller heard about my hobby interests, he just gave it to me for free. Thank you!

    The copyright date on the ROM code is 1987. It's a great unit. Reliable and nice. I've used it as an oscilloscope (but not logic analyzer) for many projects. There are full manuals here.

    The system has a 3.5" floppy drive which it boots from. I've always been afraid of the floppies failing.

    Some years back, I made a Greaseweazle out of a Blue Pill and an old PC floppy drive. This let me transfer the system disc to my PC:

    gw read --format ibm.scan --tracks=c=0-79:h=0-1 outputfile.hfe::bitrate=500

    The HFE file can then be converted to a raw file with SAMDisk: 

    SAMDisk copy outputfile.hfe outputfile.raw

     The file system is LIF and I was able to use lifutils to extra the SYSTEM_ operating system file from the raw files. I tried to disassemble it with Ghidra in order to run my code on it, but failed (more on that later).