I like to think that, when designing this clamp, someone said "make sure it's just wide enough to hold a quad-height flip chip module". I don't want to hear anybody say "but Ethan that's just a 14" piece of square tubing." #retrocomputing#unibone#pdp11#tools
putting on the BBS Documentary on while i code for the day
one of the great finds over the years was an original DVD set of the series.
watching it on a 4:3 CRT is a totally different experience than on a widescreen HD panel. it absolutely looks better on this CRT - like watching a 90s PBS doc.
Hi #RetroComputing fans - can any of you tell me what sort of slot that is in the third position down, in this fuzzy photo of a HP desktop? It looks like an audio tape slot!
Just christened and licensed ‘truly’, a DEC Alpha 500au with the same non-commercial kit we got nearly 25 years when we switched to DEC Alpha! Welcome truly to SDF Vintage Systems! ‘ssh menu@tty.sdf.org’
I'm in over my head here. This Type 1 IBM 5170 board just won't POST. Basically the same behavior as the 5162 board I have. The POST card just displays "-- --". I have a bunch of tools that should help troubleshoot but lack the skills/knowledge to use them effectively. Ugh.
Huge shot in the dark, but does anyone have a list of the phone numbers used by Labatt Blue Line (free long distance voip calling in the 2000s on Ontario)?
Can't believe it but I'm reverse engineering another schematic. It's an #AppleII Prometheus Versacard which provides serial/parallel/clock. Hangs when I try to use it even though 74xx chips test fine. Today it is refusing to map in the ROM to $C800, must be something wrong with the latching. At least boolean logic is something I can get my head around, unlike trying to make sense of power supplies that are built on physics side-effects.
Figured out why $C800 isn't getting mapped in: because I put the card in a IIe! They hooked up USER1 to the chip that checks if IO space is being accessed. On a IIe that pin isn't USER1 anymore and is low most of the time, preventing the card from decoding addresses. Put the card in a II+ and sure enough $C800 works.
The scanned manual I found online mentions using the card in a IIe, which is clearly not possible with my card. So I went looking to see if I could find any pictures of another card and found an eBay auction with some good pictures. Sure enough, there was a later revision where USER1 isn't connected!
I was able to get the ROM to go into its built-in terminal mode. But transmit from the card doesn’t work, only receive does. All the flow lines are on so the 6850 ACIA shouldn’t be blocking transmission.
Hooked up a logic probe to the 6850 TX pin and I see activity when sending. Must be the 5V to RS232 level shifter that isn’t working. #RetroComputing#VintageComputing
I’m probably being silly, but I don’t want to permanently modify the Versacard to make it IIe compatible. So instead I’m going to modify a socket to act as an adapter.
Using a short piece of wire wrap wire I’ll jumper the pin 3 to pin 16 to keep it pulled high at all times. No need to strip the wire, the soldering iron will take car of that for me. There’s also a convenient slot in the pin spring to insert the wire into.
Back in the day #Amiga had a compression tool Imploder that famously included a soundtrack. I always thought that more applications should have one. X-Copy Pro is a software that most amiga users got quite used to, for ermmm floppy disk backups. It did have some sounds, most famously the "BONG!" that indicated op completion. It however did not have a soundtrack. It's finally time to fix that omission!
I took X-Copy, disassembled it enough to determine how it normally utilises the amiga hardware and then wrote a small patch that:
Modify the setup routine to initialize mod playback routine. Since the application itself already uses CIA-B timers I found it easier to modify the ptplayer routine to utilise CIA-A timers instead.
Modify level 2 interrupt handler that is normally used to process the keyboard communication to also process the CIA-A timers A and B of the ptplayer routine.
Modify the cleanup routine to restore original state of the CIA-A timers.
The soundtrack is the Cecconoid Amiga soundtrack trilateral.mod by @h0ffman (PS I might have been inspired by a certain clip Hoffman uses in his Twitch streams at https://www.twitch.tv/djh0ffman)
Interested in an authentic BBS experience? Check out the Bitzone under SDF Vintage Systems https://sdf.org (also available via telnet login as ‘bitzone’)