John Calhoun
@engineersneedart.com
Old Macintosh shareware author. Making things I wish existed when I was a kid.
engineersneedart.com
github.com/EngineersNeedArt
engineersneedart.com
github.com/EngineersNeedArt
I posted a 68K Macintosh "game shell" on Github if anyone wanted to dabble in writing a vintage Mac sprite-based game.
github.com/EngineersNee...
Included, a beta of "Flappy Toaster" (a game-shell demonstrator I threw together).
#vintagemac #retro_gaming #vcfmw
github.com/EngineersNee...
Included, a beta of "Flappy Toaster" (a game-shell demonstrator I threw together).
#vintagemac #retro_gaming #vcfmw
September 15, 2026 at 11:39 AM
I posted a 68K Macintosh "game shell" on Github if anyone wanted to dabble in writing a vintage Mac sprite-based game.
github.com/EngineersNee...
Included, a beta of "Flappy Toaster" (a game-shell demonstrator I threw together).
#vintagemac #retro_gaming #vcfmw
github.com/EngineersNee...
Included, a beta of "Flappy Toaster" (a game-shell demonstrator I threw together).
#vintagemac #retro_gaming #vcfmw
Love the re-creation of Steve's garage at VCFMW.
(Reminds me of Wonderfest 2026 recreating the Industrial Light & Magic model shop.)
#VCFMW
(Reminds me of Wonderfest 2026 recreating the Industrial Light & Magic model shop.)
#VCFMW
September 12, 2026 at 2:06 AM
Love the re-creation of Steve's garage at VCFMW.
(Reminds me of Wonderfest 2026 recreating the Industrial Light & Magic model shop.)
#VCFMW
(Reminds me of Wonderfest 2026 recreating the Industrial Light & Magic model shop.)
#VCFMW
Reposted by John Calhoun
Everyone loves the booth so far!
September 12, 2026 at 12:22 AM
Everyone loves the booth so far!
Vibe-coded (donʼt hate me) an optical halftone web-app designed for screen printing.
Free, your images never leave your device, no account—just enjoy it. (Send feedback if you find issues.)
Here:
engineersneedart.com/halftone/
#screenprinting #halftone
Free, your images never leave your device, no account—just enjoy it. (Send feedback if you find issues.)
Here:
engineersneedart.com/halftone/
#screenprinting #halftone
September 9, 2026 at 9:54 PM
Vibe-coded (donʼt hate me) an optical halftone web-app designed for screen printing.
Free, your images never leave your device, no account—just enjoy it. (Send feedback if you find issues.)
Here:
engineersneedart.com/halftone/
#screenprinting #halftone
Free, your images never leave your device, no account—just enjoy it. (Send feedback if you find issues.)
Here:
engineersneedart.com/halftone/
#screenprinting #halftone
Reposted by John Calhoun
Coming to VCF Midwest? If you're like me, it's hard trying to remember where everything is, especially with VCF taking up the ENTIRE expo hall this year.
So I made this tool last night: geerlingguy.github.io/vcfmw21-map/
Now it's a lot easier to find exhibitors! #vcfmw
So I made this tool last night: geerlingguy.github.io/vcfmw21-map/
Now it's a lot easier to find exhibitors! #vcfmw
VCF Midwest 21 — interactive table guide
Interactive floor plan for Vintage Computer Festival Midwest 21. Tap any table to see who is exhibiting there, what they are showing, and where to find them.
geerlingguy.github.io
September 7, 2026 at 12:09 AM
Coming to VCF Midwest? If you're like me, it's hard trying to remember where everything is, especially with VCF taking up the ENTIRE expo hall this year.
So I made this tool last night: geerlingguy.github.io/vcfmw21-map/
Now it's a lot easier to find exhibitors! #vcfmw
So I made this tool last night: geerlingguy.github.io/vcfmw21-map/
Now it's a lot easier to find exhibitors! #vcfmw
I'm enjoying diving into screen-printing. (White ink on a black sheet of French paper.)
The Moon from the recent Artemis mission.
Experimenting with exposure times, half-toning vs. dithering (vibe-coding custom Python algorithms and testing them).
#screenprinting #silkscreen #nasa #artemis_art
The Moon from the recent Artemis mission.
Experimenting with exposure times, half-toning vs. dithering (vibe-coding custom Python algorithms and testing them).
#screenprinting #silkscreen #nasa #artemis_art
September 5, 2026 at 10:32 PM
I'm enjoying diving into screen-printing. (White ink on a black sheet of French paper.)
The Moon from the recent Artemis mission.
Experimenting with exposure times, half-toning vs. dithering (vibe-coding custom Python algorithms and testing them).
#screenprinting #silkscreen #nasa #artemis_art
The Moon from the recent Artemis mission.
Experimenting with exposure times, half-toning vs. dithering (vibe-coding custom Python algorithms and testing them).
#screenprinting #silkscreen #nasa #artemis_art
Trying to get a screen-printing setup in the basement. First screen burned—test-strips at various exposure intervals to try to dial in my home-made, UV, LED jank-ass light.
I'll pull a print tomorrow and see if I need to burn another test-strip with different intervals.
#screenprinting #silkscreen
I'll pull a print tomorrow and see if I need to burn another test-strip with different intervals.
#screenprinting #silkscreen
August 28, 2026 at 1:56 AM
Trying to get a screen-printing setup in the basement. First screen burned—test-strips at various exposure intervals to try to dial in my home-made, UV, LED jank-ass light.
I'll pull a print tomorrow and see if I need to burn another test-strip with different intervals.
#screenprinting #silkscreen
I'll pull a print tomorrow and see if I need to burn another test-strip with different intervals.
#screenprinting #silkscreen
Probably the album that had the most profound effect on me (for some reason).
📣 We’re excited to announce that Reckoning will be the newest release in the Definitive Sound Series’ acclaimed audiophile vinyl series on September 18. You can pre order here: interscope.com/products/rec...
August 19, 2026 at 5:13 PM
Probably the album that had the most profound effect on me (for some reason).
A professor Dr. Bernd Ulmann is the analog computer expert these days. After mailing my "Anna" analog computer kit to him he was able to "program" a Lorenz attractor.
Schematic, layout (extra pots and an additional integrator were needed/added) and the scope.
#electronics #analog #chaos
Schematic, layout (extra pots and an additional integrator were needed/added) and the scope.
#electronics #analog #chaos
August 19, 2026 at 3:26 AM
A professor Dr. Bernd Ulmann is the analog computer expert these days. After mailing my "Anna" analog computer kit to him he was able to "program" a Lorenz attractor.
Schematic, layout (extra pots and an additional integrator were needed/added) and the scope.
#electronics #analog #chaos
Schematic, layout (extra pots and an additional integrator were needed/added) and the scope.
#electronics #analog #chaos
"Anna"
I wrapped up (after more than 6 months?) my little #analogcomputer trainer (hobbyist machine—whatever).
It's open—Github repo linked here. I made a few kits available (they were expensive to make though—but nice and with a nice manual!).
#electronics
github.com/EngineersNee...
I wrapped up (after more than 6 months?) my little #analogcomputer trainer (hobbyist machine—whatever).
It's open—Github repo linked here. I made a few kits available (they were expensive to make though—but nice and with a nice manual!).
#electronics
github.com/EngineersNee...
July 8, 2026 at 12:13 PM
"Anna"
I wrapped up (after more than 6 months?) my little #analogcomputer trainer (hobbyist machine—whatever).
It's open—Github repo linked here. I made a few kits available (they were expensive to make though—but nice and with a nice manual!).
#electronics
github.com/EngineersNee...
I wrapped up (after more than 6 months?) my little #analogcomputer trainer (hobbyist machine—whatever).
It's open—Github repo linked here. I made a few kits available (they were expensive to make though—but nice and with a nice manual!).
#electronics
github.com/EngineersNee...
Using a stereo digital camera (dated and not designed for low-light levels). Captured Letters to Cleo in Des Moines.
(App to create stereogram from .MPO files is Stereographer.)
#stereophotography #letterstocleo
bsky.app/profile/kayh...
(App to create stereogram from .MPO files is Stereographer.)
#stereophotography #letterstocleo
bsky.app/profile/kayh...
July 1, 2026 at 1:27 PM
Using a stereo digital camera (dated and not designed for low-light levels). Captured Letters to Cleo in Des Moines.
(App to create stereogram from .MPO files is Stereographer.)
#stereophotography #letterstocleo
bsky.app/profile/kayh...
(App to create stereogram from .MPO files is Stereographer.)
#stereophotography #letterstocleo
bsky.app/profile/kayh...
Islamic filigree created in Affinity Designer (a couple of hours), cut out of card-stock with a laser (about 5 minutes).
So delicate… I was surprised it held together.
(Beginning experiments in shadow puppetry.)
#shadowpuppets
So delicate… I was surprised it held together.
(Beginning experiments in shadow puppetry.)
#shadowpuppets
June 30, 2026 at 10:32 PM
Islamic filigree created in Affinity Designer (a couple of hours), cut out of card-stock with a laser (about 5 minutes).
So delicate… I was surprised it held together.
(Beginning experiments in shadow puppetry.)
#shadowpuppets
So delicate… I was surprised it held together.
(Beginning experiments in shadow puppetry.)
#shadowpuppets
I hope to finally get this to Steam this time (and this summer).
June 18, 2026 at 3:41 AM
I hope to finally get this to Steam this time (and this summer).
Modular means I can add a breadboard to "Anna" if need be…
This harmonograph program has not 2, but 4 pendulums! (2 pendulums for the X axis and 2 pendulums for the Y.)
That's over 52 wires of code!
(The longest program I have, um, written yet.)
#analogcomputing #electronics
This harmonograph program has not 2, but 4 pendulums! (2 pendulums for the X axis and 2 pendulums for the Y.)
That's over 52 wires of code!
(The longest program I have, um, written yet.)
#analogcomputing #electronics
May 12, 2026 at 3:11 AM
Modular means I can add a breadboard to "Anna" if need be…
This harmonograph program has not 2, but 4 pendulums! (2 pendulums for the X axis and 2 pendulums for the Y.)
That's over 52 wires of code!
(The longest program I have, um, written yet.)
#analogcomputing #electronics
This harmonograph program has not 2, but 4 pendulums! (2 pendulums for the X axis and 2 pendulums for the Y.)
That's over 52 wires of code!
(The longest program I have, um, written yet.)
#analogcomputing #electronics
Happy Mother's Day, mom. Wish you were still here. 🥹
May 10, 2026 at 12:03 PM
Happy Mother's Day, mom. Wish you were still here. 🥹
"Programmed" a simple harmonograph on the analog computer. One pendulum (displays red), a 2nd (yellow) and both mixed (green)—sometimes adding, sometimes subtracting.
Switch to XY-oscilloscope mode for the Lissajous curve.
(Next: double the program to 4 pendulums.)
#analog_computer #electronics
Switch to XY-oscilloscope mode for the Lissajous curve.
(Next: double the program to 4 pendulums.)
#analog_computer #electronics
May 10, 2026 at 2:53 AM
"Programmed" a simple harmonograph on the analog computer. One pendulum (displays red), a 2nd (yellow) and both mixed (green)—sometimes adding, sometimes subtracting.
Switch to XY-oscilloscope mode for the Lissajous curve.
(Next: double the program to 4 pendulums.)
#analog_computer #electronics
Switch to XY-oscilloscope mode for the Lissajous curve.
(Next: double the program to 4 pendulums.)
#analog_computer #electronics
(Little blurry…) "Anna" programmed for Lotka-Volterra (prey/predator) equation.
1st display mode: a strip chart with prey population red, predator orange. (Predator's population lags prey's.)
2nd display mode a kind of XY oscilloscope plotting pop. in "phase space".
#analogcomputer #electronics
1st display mode: a strip chart with prey population red, predator orange. (Predator's population lags prey's.)
2nd display mode a kind of XY oscilloscope plotting pop. in "phase space".
#analogcomputer #electronics
May 5, 2026 at 11:57 PM
(Little blurry…) "Anna" programmed for Lotka-Volterra (prey/predator) equation.
1st display mode: a strip chart with prey population red, predator orange. (Predator's population lags prey's.)
2nd display mode a kind of XY oscilloscope plotting pop. in "phase space".
#analogcomputer #electronics
1st display mode: a strip chart with prey population red, predator orange. (Predator's population lags prey's.)
2nd display mode a kind of XY oscilloscope plotting pop. in "phase space".
#analogcomputer #electronics
"Spring+Mass" is, I have heard, the "Hello World" of analog computing.
"Anna's" pair of integrators connected in a circular arrangement give rise to oscillation. Pots control spring constant, dampening, mass…
(ADCs & an ESP32 on "MAIN" give a visual representation.)
#analogcomputing #electronics
"Anna's" pair of integrators connected in a circular arrangement give rise to oscillation. Pots control spring constant, dampening, mass…
(ADCs & an ESP32 on "MAIN" give a visual representation.)
#analogcomputing #electronics
May 1, 2026 at 7:01 PM
"Spring+Mass" is, I have heard, the "Hello World" of analog computing.
"Anna's" pair of integrators connected in a circular arrangement give rise to oscillation. Pots control spring constant, dampening, mass…
(ADCs & an ESP32 on "MAIN" give a visual representation.)
#analogcomputing #electronics
"Anna's" pair of integrators connected in a circular arrangement give rise to oscillation. Pots control spring constant, dampening, mass…
(ADCs & an ESP32 on "MAIN" give a visual representation.)
#analogcomputing #electronics
I "programmed" (patched) Lunar Lander. A special "metering mode" on "Anna" reads analog voltages representing gravity, thrust, velocity, position—displays a small lunar module descending.
(Breadboard is not for prototyping—it's how you program/wire-up the modules!)
#analogcomputing #electronics
(Breadboard is not for prototyping—it's how you program/wire-up the modules!)
#analogcomputing #electronics
April 30, 2026 at 9:47 PM
I "programmed" (patched) Lunar Lander. A special "metering mode" on "Anna" reads analog voltages representing gravity, thrust, velocity, position—displays a small lunar module descending.
(Breadboard is not for prototyping—it's how you program/wire-up the modules!)
#analogcomputing #electronics
(Breadboard is not for prototyping—it's how you program/wire-up the modules!)
#analogcomputing #electronics
The final (1.0) boards/PCBs for my hobbyist analog computer (Anna) are finally rolling in from Asia. As I complete the manual, I'm playing with "programs" on it.
I switch to "scope mode" and reset the integrators to display a "harmonigraph" simulation I wired up.
#analogcomputing #electronics
I switch to "scope mode" and reset the integrators to display a "harmonigraph" simulation I wired up.
#analogcomputing #electronics
April 30, 2026 at 6:35 PM
The final (1.0) boards/PCBs for my hobbyist analog computer (Anna) are finally rolling in from Asia. As I complete the manual, I'm playing with "programs" on it.
I switch to "scope mode" and reset the integrators to display a "harmonigraph" simulation I wired up.
#analogcomputing #electronics
I switch to "scope mode" and reset the integrators to display a "harmonigraph" simulation I wired up.
#analogcomputing #electronics
Last for today: a scan of
an ImageWriter printout of
a screenshot of
Glider 1.0.
an ImageWriter printout of
a screenshot of
Glider 1.0.
April 17, 2026 at 2:42 PM
Last for today: a scan of
an ImageWriter printout of
a screenshot of
Glider 1.0.
an ImageWriter printout of
a screenshot of
Glider 1.0.
Final "boss" in Glider: the cat that tried to obstruct your glider from escaping the house.
An early sketch—the paw a separate bitmap could animate (the swat!).
The cat "trick" was: move into pawRect & retreat quickly (swat misses). Then dive back in. (The cat waited a second or so between swats.)
An early sketch—the paw a separate bitmap could animate (the swat!).
The cat "trick" was: move into pawRect & retreat quickly (swat misses). Then dive back in. (The cat waited a second or so between swats.)
April 17, 2026 at 2:39 PM
Final "boss" in Glider: the cat that tried to obstruct your glider from escaping the house.
An early sketch—the paw a separate bitmap could animate (the swat!).
The cat "trick" was: move into pawRect & retreat quickly (swat misses). Then dive back in. (The cat waited a second or so between swats.)
An early sketch—the paw a separate bitmap could animate (the swat!).
The cat "trick" was: move into pawRect & retreat quickly (swat misses). Then dive back in. (The cat waited a second or so between swats.)
Here's another early Glider sketch showing tables and candlesticks. For the tables, the bases were bitmaps, but the vertical support and table-top were rendered (allowing arbitrary heights/widths).
The candle was a bitmap with a flickering bitmap flame.
Just getting started here…
The candle was a bitmap with a flickering bitmap flame.
Just getting started here…
April 17, 2026 at 2:33 PM
Here's another early Glider sketch showing tables and candlesticks. For the tables, the bases were bitmaps, but the vertical support and table-top were rendered (allowing arbitrary heights/widths).
The candle was a bitmap with a flickering bitmap flame.
Just getting started here…
The candle was a bitmap with a flickering bitmap flame.
Just getting started here…
Very early Glider… Before I knew how to display an arbitrary PICT (picture, created with MacPaint, for example), I rendered icons instead (32 pixels by 32 pixels). Sketched on graph paper first…
A very different glider on the left. The one on the right would win out (when I grew beyond 32 pixels).
A very different glider on the left. The one on the right would win out (when I grew beyond 32 pixels).
April 17, 2026 at 2:20 PM
Very early Glider… Before I knew how to display an arbitrary PICT (picture, created with MacPaint, for example), I rendered icons instead (32 pixels by 32 pixels). Sketched on graph paper first…
A very different glider on the left. The one on the right would win out (when I grew beyond 32 pixels).
A very different glider on the left. The one on the right would win out (when I grew beyond 32 pixels).