the power supply (far left) seems to require low-voltage AC. there must be an external power transformer.
the motherboard, sans dust. there's still some gunk left, so you know what's coming up next...
ColorCoral! it's soon going to turn a nasty shade of grey.
bleh
ooh a quad 555 timer. must be for the joystick port.
the infrared receiver (for the keyboard) is under the shield.
washed and dried the case. I had a hard time getting the front off, it's press fit into those little holes on the front. mine was already loose, otherwise I wouldn't have done it
I guess they cheaped out and didn't get fasteners
which is odd because right here they have a brass insert
putting it all back together
the pins on this 0.1" header are round instead of square 🤔
JJLKLPTVMDSCPA. IO
what does it all mean
this computer has no D-sub connectors. just 0.1" headers. to save money? perhaps. but IBM also sold the RT PC, a high end workstation, with the same sort of connectors.
i wonder if i should design a Snark Barker sidecar for the PCjr. obviously it would be called the "Snark Barker Snide Car"
finally got around to powering it up, and it works!
i don't have the external power brick so i just used my bench supply. oh yeah i have no keyboard 😂
• • •
Missing some Tweet in this thread? You can try to
force a refresh
i printed a new panel insert that has two BNC sockets on it (the original probes would have had captive cables)
the tricky part is that this oscilloscope has a 333K ohm input impedance instead of 1M like umm every other scope on the planet. fortunately someone designed a little conversion circuit...
in honor of Sim Wong Hoo, here's a quick historical review of the Sound Blaster! 🧵
but first we have to go back to their first sound card, the Creative Music System from 1987. (image credit: Bratgoul on Wikipedia)
this card has some special "CMS-301" chips. if you peel back the sticker, they have had their top marks removed. they're actually SAA1099 synthesizer chips made by Philips. Creative wrote music composition software for musicians on the PC.