@hollowone This is a picture from an event I presented at in October. The memory map has separate reserved space for both the CGA and MDA cards. Later EGA and VGA took over the CGA address space, but the MDA address space was left reserved.

These are simple memory mapped devices; software can write to any spot in the memory map to generate text or graphics on the connected display.

You can see the MDA display being used with a debugger to debug the graphics program.

#retrocomputing

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Pair programming an debugging 1990s style. The 80486 based computer has both a VGA card and an MDA card, giving it dual screen capability.

Happiness is buying a $5 eBay card, having it arrive with excellent packaging and it being as described, adding it to your 486, and not having anything go wrong that then requires 3 hours of debugging.

(I added a cheap Hercules clone to my 486 so that I can enjoy dual screens without having to steal an original IBM MDA card from an XT.)

#retrocomputing

Would you like to see UNIX V4 on MissPiggy? #retrocomputing #vintagecomputing #unix #softwarepreservation

EtherSlip users - I have found another bug in the Etherslip driver distributed in the Crynwr packet driver collection. This bug is in the simulated ARP handling that the driver provides while emulating Ethernet. It can corrupt a random six bytes in your network program's memory.

I'm going to change mTCP to not send ARP requests at all when a SLIP connection is in use. I've also patched EtherSlip and will make that available for WATTCP users after doing some more testing.

#retrocomputing

So I got myself a couple of IBM PS/2 model P70 386[1] luggable computers. I see they're quite the fad in some corners of the Retroverse, so I thought I'd pull my usual shenanigans and install OS/2 on one. I went with version 2.11 which is probably the most lightweight version, while also being really beautiful. I'll document my travails in this thread..

Stay tuned, more to come!

Image: My P70 duing the initial attempts at booting the OS/2 2.11 installation floppies.

[1] https://www.ardent-tool.com/8573/P70_Project.html

#Retrocomputing #Installfest #Retrohardware #IBM #OS2

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Image described in post.

#Christmas #Retrocomputing #Larry #Sierra

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Screenshot from Sierra's 1990 Christmas Card application depicting a stage with Cupid flying above it with his bow and two dead(?) lovers on the floor with arrows sticking out of their backs. 16-color EGA resolution.

@ltning Okay tags on #Peertube don't do what I think they do, so .. #Floppy #Museum #Retrocomputing #DOS

Ever wanted to connect to a public Unix system with all the thrill of a DEC terminal but the security of Ed25519?

Introducing SSHtty Gateway:  be the envy of your friends, conspire in secret, profit handsomely!

#retrocomputing

I just published v0.99 of #jSH, a #JavaScript scripting environment for #MSDOS. This is the 'little' text-mode brother to #DOjS.

- fixed `Screen` object.
- fixed `CGets()`.
- added missing include
- updated zip, mbedTLS and curl

https://github.com/SuperIlu/jSH

#RetroComputing #FreeDOS #DJGPP #RetroDev #RetroDevelopment

Stopped by the Atlanta historical computing society’s holiday party in Lawrenceville! #retrocomputing #vintagecomputing #ahcs #georgia

Happy DEC-10 Day from https://icm.museum !!

2026 will be year of 36 bits!

Come play on the two SC40s and XKL TOADs

#vintagecomputing #retrocomputing

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A PDP-10 model KA

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4 PDP-10s in a row

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PDP-10 model KA

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PDP-10 model KI

Forget the chaotic Black Friday sales! 🤯 NetBSD 🚩 offers the BEST deal: it's 100% FREE! Always has been, always will be. Perfect for self-hosters and anyone seeking pure, open-source goodness without spending a dime. No catches, just solid OS. #NetBSD #BlackFriday #FreeSoftware #SelfHost #RetroComputing #OpenSource #Linux #RunBSD

This AT&T demo diskette was discovered in a large box of unsorted floppies. The instructions are for running it on a 3B2 computer which we have running as “lcm3b2” and is remotely accessible. Would you like to know what is on this diskette? #retrocomputing #vintagecomputing #floppydisk #unix

@magnetic_tape I can't remember the DPI setting exactly, but it's probably 144 DPI. I cheated and used "double strike" on the line to ensure the image was dark, but it probably didn't make a difference. (It matters on my lower quality printers.)

Here is the finished output:

#retrocomputing

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Bream spring keyboard keys printed on an IBM 5140 Convertible thermal printer.

The last post for today, I promise!

I wanted to test the printer repair I made four years ago before I put the machine away. It's still good!

The problem was a spring that went out of tension. The mechanism is very complex and it made the printer not print on every other line. It would advance the paper correctly, but just not print.

The printer is a thermal printer than can also take ribbons. The ribbons are unobtanium now so this is just bare fax paper.

#retrocomputing

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An IBM 5140 Convertible thermal printer printing a JPG of a beam spring keyboard mechanism.

@sycophantic That one was actually messier than it looks - it squirted a blob of whatever was inside it onto the circuit board.

Not quite a full on explosion, but it made enough smoke and mess to get my attention when it happened.

#retrocomputing

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A bad tantalum capacitor from an IBM 5140 CRT circuit board. This is right after it went bad; it spilled some of its innards. The ball of tantalum (?) was knocked off later while trying to take better pictures.

Bad Tantalum! Bad!

Why does this capacitor have three legs? It makes it easier to use machines to assemble the boards - the center leg on this one is the anode (positive) and the outer legs are cathode (negative) connections. No matter which way you insert it, you can't get it wrong.

These little guys are 4 times as expensive as two legged versions so it was replaced with a standard two legged version. It works, just make sure you get the polarity correct.

#retrocomputing

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A burnt and bad tantalum capacitor on an IBM 5140 CRT adapter ("slice") controller board.

The CRT slice on the IBM 5140 Convertible is working again - it had a blown tantalum capacitor. But the backlight on the flip-up display is totally dead, making it basically unreadable. I almost hate these things.

Has anybody successfully repaired an IBM Convertible display? My non-backlit versions often have dead rows of pixels or rows of pixels stuck on, and this one has the backlight problem.

#retrocomputing

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IBM 5140 Convertible with an external display showing a Moire pattern programmed in BASIC.

- Updated #tiff to 4.7.1

- Updated pl_mpeg

- Updated #nanoSVG

- Updated #libpng to 1.6.50

- Updated #jasper to 4.2.8

- Updated #AnimatedGIF to 2.2.0

- Moved mbedTLS config out of the source tree

- Added more examples/tests

- Added my #VCFe talk slides from May, 2025

#MSDOS #DOSGaming #retrocomputing #JavaScript #FreeDOS #creativecoding #p5js #retrodev #retrodevelopment #3dfx #OpenGL #Processing
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- fixed error message for library loading in win32

- fixed SQLite3 database opening in win32

- return empty object from GetNetworkInterfaces() on win32

- fixed curl on win32

- updated zip to 0.3.5

- Patched #Allegro 4 to support all BMP formats (backport from allegro5).

- improved documentation

- Updated to #mbedTLS 3.6.5

- Updated #cURL to 8.17.0

#MSDOS #DOSGaming #retrocomputing #JavaScript #FreeDOS #creativecoding #p5js #retrodev #retrodevelopment #3dfx #OpenGL #Processing
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I just released v1.14.0 of #DOjS on https://github.com/SuperIlu/DOjS/releases/tag/v1.140

New Features:
- SMK file playback via libsmacker
- #C64 SID playback using cRSID
- #EXIF data reading
- Sound synthesis based on MicroModSynth from @benhencke

See thread below for more release details!

#MSDOS #DOSGaming #retrocomputing #JavaScript #FreeDOS #creativecoding #p5js #retrodev #retrodevelopment #3dfx #OpenGL #Processing
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I pushed an update to #DOStodon (the #Mastodon client for MS-DOS):

- Updated DOStodon binaries to latest #DOjS release v1.14.0

Grab it at https://github.com/SuperIlu/DOStodon

Screenshot is showing both, the DOS ( @DOSBox_Staging ) and the the win32 version (Win10).

#Javascript #RetroComputing #MSDOS #CreativeCoding #MastodonClient #FreeDOS #DJGPP

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screenshot of two instances of a text based mastodon client both showing a timeline for the tag CatsOfMastodon