Discover and read the best of Twitter Threads about #retrocomputing
Most recents (10)
I'm hoping to do a series of articles / threads about how the PDP-12 works, by diving into its instruction set and other low-level behaviors. Here's the first one of these threads! 🧵 #pdp12 #umdpdp12 #RetroComputing 
The PDP-12 is a combination of the LINC and the PDP-8 -- both 12-bit machines. The practice was to describe memory using four octal (3-bit) values (rather than, say, 3 hexadecimal values). So, 111111111111b is "7777" (not 0xFFF) and 101010101010b is "5252" (not 0xAAA).
The PDP-12 runs in either LINC mode or PDP-8 mode at any given time, but you can arbitrarily switch between modes (and instruction sets) at any time, using ops PDP (0002) in LINC and LINC (6141) in 8-mode. Some hardware only works in LINC mode, so this is quite common.
Welcoming a new (old) printer (back) into my fleet: a LaserWriter II. It’s a workhorse of a printer from 1988 dressed in Snow White design language. #RetroComputing
I had one just like it for years that I used almost daily but jettisoned it some time ago. This one comes to me thanks to @compu_85! You can see here where he was repairing a series of these a few weeks ago.
This one has a IIg board in it which sports a ‘030 processor, up to 32MB RAM, LocalTalk, EtherTalk, RS-232, and SCSI. Here’s the first test page that “Web of Fate” printed. Page counter got reset— oops. I’ve got a WiFi232 plugged in to make it “wireless.” #RetroComputing
In Jan. 1997 I was 15 and obsessed with computers. My family happened to be in San Francisco and we drove by Moscone Center where I saw banners proclaiming that MacWorld Expo was happening. The pic is me around that time 🙂
A short thread ⬇️
#RetroComputing #Apple #Mac #macOS
A short thread ⬇️
#RetroComputing #Apple #Mac #macOS
I made a sign on a pizza box reading "SPARE MACWORLD PASS?" I only stood outside for ~10 minutes before a nice woman in a business suit gave me her pass and said "tell anyone who questions you that I'm your mom!" I went in and spent a joyful day exploring the exhibit hall.
Welcoming another Penman #penplotter turtle home. Hope to learn how to repair these and get them working again. Many thanks to @Retro_CAD for this one! #plottertwitter #RetroComputing
Here’s a video of a Penman plotter in working order.
The new Penman fails to detect the page edges during a home cycle. Without this, it can’t begin a plot correctly. Edges are detected through two small slots on either side of the turtle with an IR emitter and receiver pair. Black paper is recommended to increase edge contrast.
Did you know there were typewriters that used ball point pens to draw not just text but also graphics? I’ve collected several of these over the years. Thread: 🧵 #plottertwitter #RetroComputing
Panasonic made three models. The top shelf was the RK-P400C Penwriter which included the RS-232 port built in for computer control. They also came with a white pen for error correcting.
With computer control, the typewriter come act like a pen plotter. I scanned the RK-P400C manual: archive.org/details/panaso…
Another year just about gone, here's a quick hardware roundup of what I released during 2021!
In August I released 'ZX True Tone' (ZXTT) to generate the correct frequency to match the #ZXSpectrum's AY soundchip for Ed Brindley's #RC2014 YM/AY Soundcard.
ebay.co.uk/itm/1149516644…
In August I released 'ZX True Tone' (ZXTT) to generate the correct frequency to match the #ZXSpectrum's AY soundchip for Ed Brindley's #RC2014 YM/AY Soundcard.
ebay.co.uk/itm/1149516644…
While the AY/YM chips can use a clock up to 2MHz, the #ZXSpectrum used 1.7734MHz. So if listening to Spec music at a higher freq it'll be pitched higher, likewise lower pitch with lower freq. So I created ZXTT to let me listen to ZXSpectrum music at the exactly the correct pitch.
The end of August and start of September saw the release of two general expansion cards for the #SAMCoupe, larger versions of previous cards.
3 Way Expansion Card
ebay.co.uk/itm/1149672961…
4 Way SAM-RC2014 Bus Interface
ebay.co.uk/itm/1149635738…
(Use #RC2014 peripherals on SAM!)
3 Way Expansion Card
ebay.co.uk/itm/1149672961…
4 Way SAM-RC2014 Bus Interface
ebay.co.uk/itm/1149635738…
(Use #RC2014 peripherals on SAM!)
Passion project time! I love the HP-45 #calculator. It's beautiful on the outside, but I wanted to show people that it's beautiful on the inside, too. So, as a #coding & #retrocomputing challenge I wrote a simulator, & I'm now making it available to all. (Retweets welcomed.) 1/7
The simulator was designed for the Z80-MBC2, a computer designed by @Just4Fun_J4Fun with a #Z80 processor running CP/M. (If you like #retrocomputing, do try it.) But after some tedious wrangling, I was able to write code which also compiled for Windows, Linux & MacOS. 2/7
I like the sense of retro-tech and (unfulfilled) futures which the terminal application provides: it's a #hauntological calculator. It's also flexible: you can change what's shown on the display &, for slower machines (say, an 8MHz Z80), you can run in minimal mode for speed. 3/7
Some of you #RetroComputing folks might remember this from about a month ago, when I found a huge cache of vintage tech stuff in a dumpster. One of the items I rescued was a really neat old minitower PC - it’s time to check it out!
#PCGaming
#PCGaming
I’ll be testing it alongside this sweet @IBM “G78” 17” CRT monitor I found a few days ago, in the same pile that contained the pretty iMac G3 I tweeted about a couple hours ago
Along with being somewhat dirty, this PC has some really interesting handwritten tags on the front and back. Apparently it was known as “Spidey” and is also tagged “Hong Kong” and “South China Morning Post.” Maybe it was used in a newspaper office?
Short Thread: *Beyond* excited: with some crazy luck, I found an unused DataRover 840. This was (I think) the only commercially-released hardware actually sold by #GeneralMagic, the folks behind the wildly-inventive Magic Cap Operating System. @generalmagicmov #retrocomputing
As if finding an unused & functional DataRover wasn't awesome enough, this one came with the difficult-to-find proprietary serial cable, which means it's theoretically possible that I'll be able to connect this to one of my mid-90s-era computers to sync data + install apps
It's also possible that the same cable will work with my other #MagicCap device, the Sony PIC-1000, which would be really cool
I received an email from John Graham-Cumming telling me my code was in the original Terminator movie. And it's true!
Here's the still from the movie:
Here's the still from the movie:
and here's the article from the May 1984 issue of 73 Magazine:
