Ed S boosted

fforth - small Forth written in C 

Ed S boosted

Back in 2010 I was playing with a cheap graphing calculator, the Sentry Ca756. It was programmable and I wrote a game for it. Then the calculator died before I typed the game in.

Last night I found the file on my drive so I typed it into BBC BASIC, converting it line by line. So I finally fot to see my game!

Only had one logic error, the line after LBL 7 is L>0=>GOTO 1 and should be L<0=>GOTO 1

I think there are other syntax errors in the Sentry version but it doesn't really matter. 😁

Ed S boosted

@niconiconi The CDC 6000 series (1964) had register B0 hardwired to 0.

Ed S boosted

#TIL In the Apollo Guidance Computer, register 7 is hardwired to zero, allowing one to zero out other registers, or to access the first element in the (base+offset) addressing mode.

I always thought the "$0 register" is a neat trick invented by MIPS. So this idea was actually much older...

Ed S boosted
Ed S boosted
#retrocomputing moment of the day. A ~7 minute marketing video on the massively parallel Thinking Machines CM-2 from back in the late-80s. 64K processors in 1988 w/28GFLOPS peak. Wow. youtu.be/BVtHh9JoS3s youtu.be/BVtHh9JoS3s
Ed S boosted

@bhtooefr That Omni laptop is awesome.

The UK #retrocomputing scene is amazing.

Great series of articles on CPU design and a great critique of , by Dan Luu:

CPU internals series:
-CPU bugs
-New CPU features since the 80s
-A brief history of branch prediction
-The cost of branches and integer overflow checking in real code
- Why CPU development is hard
- Verilog sucks, part 1
- Verilog sucks, part 2

Index at foot of this page:

(Verilog seems to the best among a collection of poor choices.)

Ed S boosted

if you like #retroComputing, there's also retroComputingForum.com run by @EdS and other former members of their community that used to be on #GooglePlus before it shut down.

See also mastodon.sdf.org/@EdS/10222091

Hey fans, don't forget to sign up to the forum! Have a look around - it's irresistible:

(Not irresistible in all jurisdictions.)

De-duplicating in-order with
where we compare

awk '!visited[$0]++' your_file > deduplicated_file
awk '!v[$0]++'

with the more robust forms
awk '!($0 in seen); {seen[$0]}'
awk '!($0 in s); s[$0]'

with the ungolfed version

awk '{ if (! visited[$0]) { print $0; visited[$0] = 1 } }'

and also compare awk with and find the README for the one true awk
"NOTE: This version uses ANSI C, as you should also."


via the discussion at

Ed S boosted

After fixing the "memory write" timing violation, my breadboard #Z80 completed the π calculation program flawlessly, and was able to calculate π to 500+ digits.

In the troubleshooting process, boards were rewired based on a "bus-centric" approach - always use a row of rightmost boards as the system bus, so new modules can be daisy-chained, and the bus can be probed easily.

The Arduino board is only used as a PSU & USB serial, no cheating here.

TODO: in-system EEPROM programmer, video.


Ed S boosted

My old #ABC80 is restored and working again. This one is nearly 40 years old. #z80 #retrocomputing

Ed S boosted

"How computing's first 'killer app' changed everything"

If you're my age, you probably learned how to use VisiCalc on a 6502-based machine as your first introduction to spreadsheets.

60 freshly launched satellites strung out like beads on a wire.


"SpaceX Starlink objects train 24 May 2019. The train of Starlink satellites passing over Leiden, the Netherlands, about 22.5 hours after launch."

Video by Marco Langbroek. Launch by SpaceX: single launch; twice re-used booster safely landed on drone ship; both fairing halves recovered; 60 Starlink satellites deployed.

Ed S boosted

"They were covered in (what else?) dust, but they were there, all 172 of them, each one containing about 2,500 feet of tape. The only problem was that they were in a format so obsolete that the data was beyond O'Brien's reach. He sent an email to NASA, offering to repatriate the tapes, but the agency politely declined."

Ed S boosted

@thomasfuchs This is haunting me. Possibly the worst example of key placement in history.

Ed S boosted

Run CP/M on your C64 – using Emulation!
#commodore #c64 #cpm #retrocomputing
The Roßmöller CP/M Emulator for C64 "borrowed" an 8080 emulator for 6502, and the CP/M OS.

Ed S boosted

Interesting on-line puzzle game. Linjat. Read the "How To Play" and "Tutorial", then give the game a go.


#Puzzles #Entertainment

For more, check out Simon Tatham's Portable Puzzle Collection [ chiark.greenend.org.uk/~sgtath ]


Ed S boosted

This is what I learned to "program" on. It wasn't until a couple years later that dad got a and I started to learn BASIC and 6502 stuff. I have no real recollection of how this thing worked. I feel old.

Show more
Mastodon @ SDF

"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko