| Codeberg | https://codeberg.org/stepleton |
| Obscure 1985 BSD workstation | http://mg-1.uk |
| U.S. call sign | WSĂATO |
Do you have 5.25" and 8" floppy disks that are spare, low-quality, degrading, or just generally in bad shape?
I'd like to take my floppy disk data recovery game to the next level. I have equipment, but there's no substitute for experience. Therefore I'm looking for loose collections of old floppy disks to practice on. I'm especially interested in working with disks where the binder affixing the media to the donut is starting to fail.
I'm in London; will pay shipping; can pick up disks around here as well. Boosts are appreciated!
Definitely riding the struggle bus trying to fix this #Tektronix 4907 power supply. A pretty simple linear supply that blows a fuse 33% of the times you turn it on.
Things it's not:
Find the schematic on page 208 of this PDF if you'd like to play along...
Here is a wiring diagram if you'd like to try to hack up your own Farallon EtherMac AAUI MAU to work with AUI. It's not as simple as connecting the right wires together, since AAUI usually supplies +5V power while AUI supplies +12V. The answer is to use a voltage regulator to make +5V from +12V, or what I've used myself is a cool-running buck converter like the Recom R-78E5.0 series. I've used the 1A variant, not because the EtherMac consumes 1A (nowhere close) but because I have a bunch of these buck converters handy for various projects.
The diagram also shows capacitors connecting various "Shield" pins to ground. The standard defining AUI states that these pins must be "capacitively coupled" to Vc (which I've recklessly labeled GND) but offers no further guidance for the sake of non-wizards like me. I was not able to measure any capacitance between shield pins and Vc on a real MAU that I own, so I simply didn't fit any: the shield lines terminate on the PCB with no connection anywhere. AUI cables are allowed to be up to 50 metres long, and I'm guessing the coupling is meant to accommodate that. My ribbon cable is 5 cm long, so I'm guessing it does not matter.
Here is some potatovision proof of the AUI-hacked Farallon EtherMac AAUI #Ethernet MAU mentioned in this post working with #mTCP on an IBM PC/AT (with some help from an old Netgear twisted pair to WiFi adapter).
What I haven't done yet is verify that the AAUI connector still works, but I'd bet it does: all of its wires just pass through the board directly to the MAU.
AAUI-to-AUI. Plenty of retro machines have only a 15-pin D-sub AUI connector for #Ethernet . To hook up anything that looks like a modern Ethernet cable, you need an adapter called a MAU. And while AUI to 10BASE-T MAUs used to accumulate in IT department drawers like fleas, these days they're surprisingly hard to find for a reasonable price. Go on over to eBay and try it now...
AAUI (note extra A) is Apple's AUI: much the same thing but with a funky connector. You can find 15 of them for $30 or just one for $10. So, is it possible to adapt an AAUI MAU to AUI?
Yes.
