@gloriouscow.bsky.social
Developer of MartyPC - a cycle-accurate IBM PC/XT Emulator
https://github.com/dbalsom/martypc
and fluxfox - a PC floppy disk image library
https://github.com/dbalsom/fluxfox
Retro enthusiast and shameless computer geek
https://github.com/dbalsom/martypc
and fluxfox - a PC floppy disk image library
https://github.com/dbalsom/fluxfox
Retro enthusiast and shameless computer geek
Now I just need to find a third way to put cats on floppy disks.
Print Pixel Art to a Floppy Disk
Print Pixel Art to a Floppy Disk
Hackaday Article
hackaday.com
January 5, 2026 at 12:21 AM
Now I just need to find a third way to put cats on floppy disks.
Reposted
For the final day of #DOScember 2025 here is part 4 of my #IBM5150 restore series. With lots of help from the community, I try to trace down what IC(s) are keeping the board from booting.
Happy Janky New Year! IBM 5150 will return!
youtu.be/p_PW85AOUFg
#RetroComputing #VintageeComputing #IBMPC
Happy Janky New Year! IBM 5150 will return!
youtu.be/p_PW85AOUFg
#RetroComputing #VintageeComputing #IBMPC
IBM 5150 Restoration Part 04 - 8088 CPU Hijinks
YouTube video by Alan Grassia
youtu.be
January 1, 2026 at 1:41 AM
For the final day of #DOScember 2025 here is part 4 of my #IBM5150 restore series. With lots of help from the community, I try to trace down what IC(s) are keeping the board from booting.
Happy Janky New Year! IBM 5150 will return!
youtu.be/p_PW85AOUFg
#RetroComputing #VintageeComputing #IBMPC
Happy Janky New Year! IBM 5150 will return!
youtu.be/p_PW85AOUFg
#RetroComputing #VintageeComputing #IBMPC
Reposted
Intel announced the 8087 floating-point chip in 1980. Now I have a blog post that explains a small part of the microcode in this chip.
www.righto.com/2025/12/8087...
www.righto.com/2025/12/8087...
Conditions in the Intel 8087 floating-point chip's microcode
In the 1980s, if you wanted your computer to do floating-point calculations faster, you could buy the Intel 8087 floating-point coprocessor ...
www.righto.com
December 30, 2025 at 7:54 PM
Intel announced the 8087 floating-point chip in 1980. Now I have a blog post that explains a small part of the microcode in this chip.
www.righto.com/2025/12/8087...
www.righto.com/2025/12/8087...
love me some CRTC abuse
Experimenting with the BBC Micro's 6845 CRTC to do some smooth full screen hardware scrolling. Not something I've attempted before and I can see a number of possibilities. This is a simple Mode 5 dynamically generated gradient that I'd have a lot of difficulty moving at this speed in software. 🔊
December 30, 2025 at 10:07 PM
love me some CRTC abuse
Reposted
Here are the DOS game trivia quiz questions I made for an event earlier in the month: youtu.be/z3mGQgVXkp8
They are all pre-Wolfenstein-3D, but most have some sort of visual clue to help out.
Let me know your score :-)
They are all pre-Wolfenstein-3D, but most have some sort of visual clue to help out.
Let me know your score :-)
How well do you know your early DOS game trivia?
YouTube video by The Oldskool PC
youtu.be
December 30, 2025 at 4:48 PM
Here are the DOS game trivia quiz questions I made for an event earlier in the month: youtu.be/z3mGQgVXkp8
They are all pre-Wolfenstein-3D, but most have some sort of visual clue to help out.
Let me know your score :-)
They are all pre-Wolfenstein-3D, but most have some sort of visual clue to help out.
Let me know your score :-)
Yes, thank you Bluesky, I can clearly see the similarities.
December 28, 2025 at 6:13 AM
Yes, thank you Bluesky, I can clearly see the similarities.
I've released my tool for encoding pixel art on floppy disk tracks.
Because that is surely a thing that people will want to do? I don't know. I just get ideas and dumb stuff happens.
github.com/dbalsom/flux...
#retrocomputing #floppy #floppydisk
Because that is surely a thing that people will want to do? I don't know. I just get ideas and dumb stuff happens.
github.com/dbalsom/flux...
#retrocomputing #floppy #floppydisk
December 28, 2025 at 3:12 AM
I've released my tool for encoding pixel art on floppy disk tracks.
Because that is surely a thing that people will want to do? I don't know. I just get ideas and dumb stuff happens.
github.com/dbalsom/flux...
#retrocomputing #floppy #floppydisk
Because that is surely a thing that people will want to do? I don't know. I just get ideas and dumb stuff happens.
github.com/dbalsom/flux...
#retrocomputing #floppy #floppydisk
Reposted
I was honored to participate in the annual Big Red Arrow Club Christmas Trivia Quiz this year, not only did I participate on a team, but had a lot of fun creating questions for the other team.
After the holidays, I'll post my question block at max quality for everyone else to test their DOS skills.
After the holidays, I'll post my question block at max quality for everyone else to test their DOS skills.
Big Red Arrow Club Gets Festive: Holiday Quiz Challenge
YouTube video by Big Red Arrow Club
youtu.be
December 24, 2025 at 8:28 PM
I was honored to participate in the annual Big Red Arrow Club Christmas Trivia Quiz this year, not only did I participate on a team, but had a lot of fun creating questions for the other team.
After the holidays, I'll post my question block at max quality for everyone else to test their DOS skills.
After the holidays, I'll post my question block at max quality for everyone else to test their DOS skills.
Reposted
🎥 New #IBM5150 Video Drop 🎞️
In Part 3 of my IBM 5150 restoration series for #DOScember, I check for the 4.77MHz clock signal on the motherboard and give it a ultrasonic bath.
(Sorry about the choppy audio, not sure what went wrong.)
youtu.be/pedaVnDbGm0
#IBMPC #VintageComputing #RetroComputing
In Part 3 of my IBM 5150 restoration series for #DOScember, I check for the 4.77MHz clock signal on the motherboard and give it a ultrasonic bath.
(Sorry about the choppy audio, not sure what went wrong.)
youtu.be/pedaVnDbGm0
#IBMPC #VintageComputing #RetroComputing
IBM 5150 Restoration Part 03 - Clock Signal Test
YouTube video by Alan Grassia
youtu.be
December 23, 2025 at 8:10 PM
🎥 New #IBM5150 Video Drop 🎞️
In Part 3 of my IBM 5150 restoration series for #DOScember, I check for the 4.77MHz clock signal on the motherboard and give it a ultrasonic bath.
(Sorry about the choppy audio, not sure what went wrong.)
youtu.be/pedaVnDbGm0
#IBMPC #VintageComputing #RetroComputing
In Part 3 of my IBM 5150 restoration series for #DOScember, I check for the 4.77MHz clock signal on the motherboard and give it a ultrasonic bath.
(Sorry about the choppy audio, not sure what went wrong.)
youtu.be/pedaVnDbGm0
#IBMPC #VintageComputing #RetroComputing
i would pay disgusting amounts of money for a floppy quilt
My Thanksgiving quilt pattern release has turned into a Christmas release - good thing it’s floppy disk themed and not holiday themed! bluepipdesigns.com/products/flo...
December 21, 2025 at 3:38 AM
i would pay disgusting amounts of money for a floppy quilt
Reposted
Appreciate you. The Retro and Vintage community is so welcoming and amazing. 🙏🏻
December 21, 2025 at 1:44 AM
Appreciate you. The Retro and Vintage community is so welcoming and amazing. 🙏🏻
Reposted
Posting here alongside my Mastodon (mcjonestech@oldbytes.space), the Seequa Chameleon also allows for customized CGA color palettes via an OPTION program! Here is Alley Cat running in red white and blue, straight from composite!
#seequa #retrocomputing
#seequa #retrocomputing
December 19, 2025 at 2:29 AM
Posting here alongside my Mastodon (mcjonestech@oldbytes.space), the Seequa Chameleon also allows for customized CGA color palettes via an OPTION program! Here is Alley Cat running in red white and blue, straight from composite!
#seequa #retrocomputing
#seequa #retrocomputing
Reposted
Did you know the 1982 Seequa Chameleon could save BIOS configurations via a DOS program? If you’re thinking it did so via a button battery, you’d be wrong! The Chameleon used this dinky XD2210 64x4 NOVRAM memory chip to store it!
Thanks to @gloriouscow.bsky.social for finding this!
Thanks to @gloriouscow.bsky.social for finding this!
December 18, 2025 at 6:40 PM
Did you know the 1982 Seequa Chameleon could save BIOS configurations via a DOS program? If you’re thinking it did so via a button battery, you’d be wrong! The Chameleon used this dinky XD2210 64x4 NOVRAM memory chip to store it!
Thanks to @gloriouscow.bsky.social for finding this!
Thanks to @gloriouscow.bsky.social for finding this!
Having a digital simulation of the CGA card can be very educational.
Here's a screenshot from the game ZZT, which is obviously in text mode:
#retrocomputing
Here's a screenshot from the game ZZT, which is obviously in text mode:
#retrocomputing
December 14, 2025 at 10:39 PM
Having a digital simulation of the CGA card can be very educational.
Here's a screenshot from the game ZZT, which is obviously in text mode:
#retrocomputing
Here's a screenshot from the game ZZT, which is obviously in text mode:
#retrocomputing
My digital logic simulation of the IBM CGA now has color!
And a release!
github.com/dbalsom/cga_...
#retrocomputing
And a release!
github.com/dbalsom/cga_...
#retrocomputing
December 14, 2025 at 12:46 AM
My digital logic simulation of the IBM CGA now has color!
And a release!
github.com/dbalsom/cga_...
#retrocomputing
And a release!
github.com/dbalsom/cga_...
#retrocomputing
A lot more progress on the IBM CGA logic simulation.
We have VRAM, and font ROM, CAS/RAS RAM timings, the shift/load clock, character glyph shift register, and somehow it all works??
Still do do: text mode attributes, and all of graphics mode...
#retrocomputing
We have VRAM, and font ROM, CAS/RAS RAM timings, the shift/load clock, character glyph shift register, and somehow it all works??
Still do do: text mode attributes, and all of graphics mode...
#retrocomputing
December 12, 2025 at 2:08 AM
A lot more progress on the IBM CGA logic simulation.
We have VRAM, and font ROM, CAS/RAS RAM timings, the shift/load clock, character glyph shift register, and somehow it all works??
Still do do: text mode attributes, and all of graphics mode...
#retrocomputing
We have VRAM, and font ROM, CAS/RAS RAM timings, the shift/load clock, character glyph shift register, and somehow it all works??
Still do do: text mode attributes, and all of graphics mode...
#retrocomputing
Reposted
so many all-women teams! every time I read about this, I discover new names and firsts. some of these women were developing machines from scratch to change the world for pennies per hour, got harassed daily, then went home to take care of multiple children in the evenings. I simply cannot fathom.
December 9, 2025 at 6:39 AM
so many all-women teams! every time I read about this, I discover new names and firsts. some of these women were developing machines from scratch to change the world for pennies per hour, got harassed daily, then went home to take care of multiple children in the evenings. I simply cannot fathom.
Some of the "new-style" CGA cards have this bodge wire, in a classic IBM yellow.
But what is it for?
#retrocomputing
But what is it for?
#retrocomputing
December 7, 2025 at 10:37 PM
Some of the "new-style" CGA cards have this bodge wire, in a classic IBM yellow.
But what is it for?
#retrocomputing
But what is it for?
#retrocomputing
Successfully dumped the ROMs from this absolutely disgusting Seequa Chameleon motherboard. You can see how clean it was *supposed* to be, underneath.
Turns out it was a version with no prior good dump, so that's cool!
@mcjonestech.com
#retrocomputing
Turns out it was a version with no prior good dump, so that's cool!
@mcjonestech.com
#retrocomputing
December 6, 2025 at 11:11 PM
Successfully dumped the ROMs from this absolutely disgusting Seequa Chameleon motherboard. You can see how clean it was *supposed* to be, underneath.
Turns out it was a version with no prior good dump, so that's cool!
@mcjonestech.com
#retrocomputing
Turns out it was a version with no prior good dump, so that's cool!
@mcjonestech.com
#retrocomputing
nand2mario has made this awesome 8086 microcode browser:
nand2mario.github.io/8086_microco...
#retrocomputing
nand2mario.github.io/8086_microco...
#retrocomputing
8086 Microcode Explorer
nand2mario.github.io
December 4, 2025 at 6:45 PM
nand2mario has made this awesome 8086 microcode browser:
nand2mario.github.io/8086_microco...
#retrocomputing
nand2mario.github.io/8086_microco...
#retrocomputing
More progress on the CGA.
Most of the visible traces are in - I've been running some traces on 2nd layer - I have no idea how they actually run, but hey, you can't see them anyway.
Most of the visible traces are in - I've been running some traces on 2nd layer - I have no idea how they actually run, but hey, you can't see them anyway.
December 4, 2025 at 3:36 AM
More progress on the CGA.
Most of the visible traces are in - I've been running some traces on 2nd layer - I have no idea how they actually run, but hey, you can't see them anyway.
Most of the visible traces are in - I've been running some traces on 2nd layer - I have no idea how they actually run, but hey, you can't see them anyway.
The PCB of the IBM CGA card is translucent, at least where there are no copper fills or solder mask. That mostly means the areas around the pads.
If you hold the card up to the light, you can see all the pads glow.
#retrocomputing
If you hold the card up to the light, you can see all the pads glow.
#retrocomputing
December 3, 2025 at 8:29 PM
The PCB of the IBM CGA card is translucent, at least where there are no copper fills or solder mask. That mostly means the areas around the pads.
If you hold the card up to the light, you can see all the pads glow.
#retrocomputing
If you hold the card up to the light, you can see all the pads glow.
#retrocomputing
Reposted
🎄🎅🏼🎥 #DOScember Video Drop 🎞️
This year for DOScember I give you the gift of me fumbling around inside an #IBM5150 PC as I try to restore it to working condition all month long.
youtu.be/Jlaypmy0PyY
#IBM #VintageComputing #RetroComputing
This year for DOScember I give you the gift of me fumbling around inside an #IBM5150 PC as I try to restore it to working condition all month long.
youtu.be/Jlaypmy0PyY
#IBM #VintageComputing #RetroComputing
IBM 5150 Restoration Part 01 - PSU
YouTube video by Alan Grassia
youtu.be
December 3, 2025 at 2:14 AM
🎄🎅🏼🎥 #DOScember Video Drop 🎞️
This year for DOScember I give you the gift of me fumbling around inside an #IBM5150 PC as I try to restore it to working condition all month long.
youtu.be/Jlaypmy0PyY
#IBM #VintageComputing #RetroComputing
This year for DOScember I give you the gift of me fumbling around inside an #IBM5150 PC as I try to restore it to working condition all month long.
youtu.be/Jlaypmy0PyY
#IBM #VintageComputing #RetroComputing
Day 2 of tracing out the IBM CGA card.
I had vivid dreams last night, all in cyan and magenta.
I had vivid dreams last night, all in cyan and magenta.
December 3, 2025 at 2:42 AM
Day 2 of tracing out the IBM CGA card.
I had vivid dreams last night, all in cyan and magenta.
I had vivid dreams last night, all in cyan and magenta.