January 28, 2025 at 12:22 PM
Credits: I've been working on this with the members of the "Opcode Collective", especially Smartest Blob and
@gloriouscow.bsky.social, who used ML to convert ROM images to microcode data and extensively analyzed the contents.
7/7
@gloriouscow.bsky.social, who used ML to convert ROM images to microcode data and extensively analyzed the contents.
7/7
September 26, 2026 at 5:00 PM
Credits: I've been working on this with the members of the "Opcode Collective", especially Smartest Blob and
@gloriouscow.bsky.social, who used ML to convert ROM images to microcode data and extensively analyzed the contents.
7/7
@gloriouscow.bsky.social, who used ML to convert ROM images to microcode data and extensively analyzed the contents.
7/7
The 6502 Opcode Periodic Table
February 23, 2026 at 5:27 PM
The 6502 Opcode Periodic Table
Went down MIDI memory lane last night [musicmaker bsky]
January 10, 2024 at 12:23 PM
Went down MIDI memory lane last night [musicmaker bsky]
My Z80 Opcode Calculator app on Google Play was updated yesterday. Undocumented opcodes are now included. Test away!
#z80 #msx #zxspectrum #amstrad
#z80 #msx #zxspectrum #amstrad
Z80 Opcode Calculator - Apps on Google Play
Get your opcodes and mnemonics on the fly.
play.google.com
February 27, 2026 at 10:21 AM
My Z80 Opcode Calculator app on Google Play was updated yesterday. Undocumented opcodes are now included. Test away!
#z80 #msx #zxspectrum #amstrad
#z80 #msx #zxspectrum #amstrad
Credits: I've been working on this with the members of the "Opcode Collective", especially Smartest Blob and @gloriouscow.bsky.social , who converted the ROM images to microcode data and extensively analyzed the contents.
September 12, 2026 at 4:24 PM
Credits: I've been working on this with the members of the "Opcode Collective", especially Smartest Blob and @gloriouscow.bsky.social , who converted the ROM images to microcode data and extensively analyzed the contents.
I did this work with the Opcode Collective, especially Smartest Blob and Gloriouscow.
The full ROM image: 8087.martypc.net#dzi=tiles%2F...
A description of the 8087 microcode: github.com/a-mcego/gran...
The full ROM image: 8087.martypc.net#dzi=tiles%2F...
A description of the 8087 microcode: github.com/a-mcego/gran...
github.com
May 30, 2026 at 5:42 PM
I did this work with the Opcode Collective, especially Smartest Blob and Gloriouscow.
The full ROM image: 8087.martypc.net#dzi=tiles%2F...
A description of the 8087 microcode: github.com/a-mcego/gran...
The full ROM image: 8087.martypc.net#dzi=tiles%2F...
A description of the 8087 microcode: github.com/a-mcego/gran...
Reconstructed SC62015 Opcode Reference For Sharp Pocket Computers
Reconstructed SC62015 Opcode Reference For Sharp Pocket Computers
Hackaday Article
hackaday.com
March 26, 2026 at 6:36 PM
Reconstructed SC62015 Opcode Reference For Sharp Pocket Computers
Par le pouvoir du 6502 et du OpCode !
Comme promis il y a près de deux ans, Joe Granato et son équipe de @nesmaker.bsky.social viennent de lancer une campagne @kickstarter.com pour concrétiser un kit de développement NES et Super Nintendo mag.mo5.com/286919/un-ou...
Un outil pour créer des jeux NES et Super Nintendo sur Kickstarter
Il y a déjà près de deux ans, Joe Granato, le créateur de NESmaker, annonçait vouloir étendre son outil à la conception de jeux Super Nintendo sous un nouveau nom, RetroGameForge (…)
mag.mo5.com
August 12, 2026 at 9:51 AM
Par le pouvoir du 6502 et du OpCode !
tired: "Just trust the compiler, it's smarter than you are"
wired: "You are going to generate a fucking jump table, so help me god"
(this has made my GPU bytecode interpreter 1.5× faster)
wired: "You are going to generate a fucking jump table, so help me god"
(this has made my GPU bytecode interpreter 1.5× faster)
February 28, 2026 at 7:52 PM
tired: "Just trust the compiler, it's smarter than you are"
wired: "You are going to generate a fucking jump table, so help me god"
(this has made my GPU bytecode interpreter 1.5× faster)
wired: "You are going to generate a fucking jump table, so help me god"
(this has made my GPU bytecode interpreter 1.5× faster)
I call Javascript Opcode, Not because its particularly low language, but because its creator is my OPP!!!!
July 24, 2025 at 1:46 AM
I call Javascript Opcode, Not because its particularly low language, but because its creator is my OPP!!!!
The 8087 was literally just a magic black box that could do reasonably fast and, more importantly, robust floating point operations. Thanks to Ken and The Opcode Collective its magic is revealed.
In 1980, Intel introduced the 8087 floating-point coprocessor chip. Plugging this chip into your IBM PC made math 100 times faster, good for CAD and spreadsheets. I opened up the chip to reverse-engineer exactly how it does complicated calculations. Let's take a look inside...
September 13, 2026 at 9:34 AM
The 8087 was literally just a magic black box that could do reasonably fast and, more importantly, robust floating point operations. Thanks to Ken and The Opcode Collective its magic is revealed.
When you spit out a markdown file full of claudeish its less a human readable explaination of things and more of an opcode printout in claude lingo
June 12, 2026 at 6:43 PM
When you spit out a markdown file full of claudeish its less a human readable explaination of things and more of an opcode printout in claude lingo
This is neat: with sufficiently careful struct layout, I can pack an opcode word into 8 bytes, be zerocopy-friendly, still have non-terrible ergonomics, and keep all of the fields correctly aligned!
![Screenshot of Rust code reading
use zerocopy::{IntoBytes, Unalign};
#[derive(Copy, Clone, IntoBytes)]
#[repr(u8)]
pub enum Opcode {
Add(Unalign<BinaryData>),
Sub(Unalign<BinaryData>),
Mul(Unalign<BinaryData>),
Div(Unalign<BinaryData>),
Atan(Unalign<BinaryData>),
Neg(Unalign<UnaryData>),
Square(Unalign<UnaryData>),
Sin(Unalign<UnaryData>),
Cos(Unalign<UnaryData>),
Tan(Unalign<UnaryData>),
}
#[derive(Copy, Clone, IntoBytes)]
#[repr(u8)]
pub enum BinaryData {
RegReg { out: u8, lhs: u8, rhs: u8, _pad: [u8; 3] },
RegImm { out: u8, lhs: u8, rhs: Unalign<f32> },
ImmReg { out: u8, rhs: u8, lhs: Unalign<f32> },
}
#[derive(Copy, Clone, IntoBytes)]
#[repr(u8)]
pub enum UnaryData {
Reg { out: u8, arg: u8, _pad: [u8; 4] },
}
fn main() {
assert_eq!(std::mem::size_of::<Opcode>(), 8);
}](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:sgqw2zixdcjtjjhrm4bw64ny/bafkreigechnlis7c7tqlxdd5kdpnf6ctfdcxsmcypkddqtt3qyrkxz66se)
September 10, 2026 at 5:57 PM
This is neat: with sufficiently careful struct layout, I can pack an opcode word into 8 bytes, be zerocopy-friendly, still have non-terrible ergonomics, and keep all of the fields correctly aligned!
sounds like a valid x86 opcode to me
"XHGSY JKSK HSG SVSGUL?" clearly must be a coded message.
Garfield June 01, 2026 https://www.gocomics.com/garfield/2026/06/01
June 1, 2026 at 11:16 AM
sounds like a valid x86 opcode to me
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
On TestFlight for iOS now.
testflight.apple.com/join/e3nSMedK
Z80, 6502, 8080, 6800, 6809, 1820, 2652
March 7, 2026 at 11:13 PM
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
On TestFlight for iOS now.
testflight.apple.com/join/e3nSMedK
Z80, 6502, 8080, 6800, 6809, 1820, 2652
It's not specifically for undefined behavior, it's a trap opcode. Every reasonable CPU has them.
x86 used not to, and people used undefined instructions for it, so Intel defined an "undefined instruction" opcode retroactively, because of course they did.
x86 used not to, and people used undefined instructions for it, so Intel defined an "undefined instruction" opcode retroactively, because of course they did.
May 26, 2026 at 7:01 AM
It's not specifically for undefined behavior, it's a trap opcode. Every reasonable CPU has them.
x86 used not to, and people used undefined instructions for it, so Intel defined an "undefined instruction" opcode retroactively, because of course they did.
x86 used not to, and people used undefined instructions for it, so Intel defined an "undefined instruction" opcode retroactively, because of course they did.
Forgot to post this last night. Fixed the Z80 emulation so that it calculates opcode T-states correctly. Then fixed the loader so it takes those into account for its timing. There were a couple of additional bugs in the loader that prevented it from working, so fixed those and…
June 11, 2026 at 10:45 AM
Forgot to post this last night. Fixed the Z80 emulation so that it calculates opcode T-states correctly. Then fixed the loader so it takes those into account for its timing. There were a couple of additional bugs in the loader that prevented it from working, so fixed those and…
one fable per opcode
July 11, 2026 at 11:24 AM
one fable per opcode