Retro computer enthusiasts: you might find this CPU opcode app useful. Please let me know of errors and omissions!
On TestFlight for iOS now.
testflight.apple.com/join/e3nSMedK
Z80, 6502, 8080, 6800, 6809, 1820, 2652
A C64-themed sticker, reading WARNING: All computers in this car are old, useless, and probably broken. Please don't break in to steal them.
I still have it! (played it like a pro: crossed arms #iykyk)
For an interesting read about it, see "Sinclair and the sunrise technology" of Ian Adamson and Richard Kennedy
rk.nvg.ntnu.no/sinclair/com...
"One of the most conspicuous economies incorporated into the design of the ZX80 was the 'touch-sensitive' or 'membrane' keypad ..."
In 1976 you could buy a KIM-1 for $245, connect it to a terminal, and start programming. In 2026 you can spend $245 on a keyboard. Progress.
You do not look like I pictured you.
There is a built-in 6502 opcode reference in Virtual Kim’s assembler view.
apps.apple.com/us/app/virtu...
Yes, I remember very well. The first PET 2001 that was imported in the Netherlands. I was having one for a review for a magazine several weeks. My first review of a home computer!
Amazed at the power and functionality and the horrible keyboard!
Commodore PET computer - white box with simple keyboard and monitor on top with flared cuboid casing. Cross between 2001 and ancient Egypt.
I remember a kid in school had a PET and they brought it in to show it off. It was just amazing looking with the futuristic case, and the monitor and tape-deck built-in. I’d never seen anything like it. Would love to have one now!
Do you remember your first PET?
People ask why I still program in 6502 assembly. Because when you JSR to a subroutine and RTS back, you know exactly what happened. Every cycle. Every bus access. There are no mysteries. Just you and the silicon.
And lets not forget the serial TTY support. Also bit-banging. Amazing what you can do with less than 2Kb of 6502 code and one 6530 RRIOT.
As is the handling of the audio tape load and save. All bit-banging! So clever for the year it was written, 1975! No AI, no libraries and books full of 6502 knowledge, the first to crack this on a 6502. The KIM-1 monitor is an excellent study onject.
Pfff. Does work have a “no stickers” rule?!
Whippersnapper. Get off my lawn you kids!
Clearly the spare goes on the Mac laptop.
The KIM-1's six 7-segment LEDs are not driven by dedicated hardware. The 6502 itself runs a loop to multiplex them. Even the display is software. This machine trusts nothing it can't do in code.
Also z80 is all zeros.
6502 has a fun mnemonic: 0xEA, like E.A., the game company that Does Nothing (Right).
VC83 BASIC project for 6502 -- targeting #AppleII and the sim65 simulator, with the capability of being extended to other platforms
#retrodev #retrocomputing #programming
Chuck Peddle didn't just design the 6502 — he designed a future where ordinary people could afford computers. The KIM-1, the PET, and everything that followed. Not bad for a chip that can't multiply.
My multi-cpu assembler, OmniAsm now supports the GB CPU as well as Z80 and 6502!! I still need to tweak the parsing of some opcodes like (FF00+XX) and SP+XX, for example, but I think the rest are working :)
The 6502 has no multiply instruction. No divide. If you want to multiply two numbers, you're doing it yourself with shifts and adds. Builds character.
A book called “AI on the Commodore 64”
Claude may be down, but the 6502 family is ready to help.
There's something meditative about entering a program one byte at a time on a KIM-1. No autocomplete. No syntax highlighting. Just you, the hex keypad, and the absolute certainty that you typed AD instead of A9 somewhere.
Bits of C64s.
New blog post - The repair of an Acorn A5000 RISC PC where the CMOS battery leaked not once, but twice in the last 30 years.
blog.tynemouthsoftware.co.uk/2026/03/acor...
Plus a seemingly unrelated hard drive access problem.
The 6502 cost $25 when it launched in 1975. The competing 8080 was $179. MOS Technology didn't just undercut the competition — they humiliated them. And they sold chips out of a jar at a trade show to prove it.
Zero page addressing: because the 6502 designers looked at 256 bytes and said "these ones are special." And they were right. Every cycle counts when you're running at 1 MHz.
Why not subscribe to re:enthused, because we REALLY love #RetroGaming and #RetroComputing
youtu.be/SDsV-n5uuqM
makertube.net/c/reenthused...
The KIM-1 had 1K of RAM and a hex keypad. No screen. No keyboard. No storage. And yet people wrote chess programs for it. In hex. By hand. We were not okay.
