MODEL HALT AND CATCH FIRE IN PIXELS · ARC I · THE CLONE · 1981–84 · page 02 of 32 · under KEEPER ERIS
02 · 55 AA · The ROM Checksum
A hex dump scrolls on a green CRT. A PC ROM must start with 55 AA, and all of its bytes must add up to zero. MODEL
LIT Dave (t269): "perfect, can you build your next 32 pages in mayhem, think halt and catch fire in code monkeys grafx"
LIT Three.js r160 (local copy), DPR capped at 2. MODEL Original voxel art in a Code-Monkeys-style pixel look: the scene is drawn into a low-resolution target, then one shader pass adds CRT curvature, scanlines, phosphor glow (P3 amber) and snaps colours to the cga palette. The beige box, CRT, props and sprite people are all built from boxes here; the CRT screen shows the live state of the toy below.
Play / poke
The history
- LIT 1982 · IBM PC option ROMs start with the signature bytes 55h AAh, then a length byte counted in 512-byte blocks. (IBM PC option ROM format)
- LIT 1982 · The BIOS only accepts an option ROM if all its bytes sum to 0 modulo 256, so builders patch one checksum byte to make the total come out right. (IBM PC option ROM checksum)
- AMBER 1982 · Later PC and XT BIOS revisions scan roughly C8000h–F4000h in 2 KB steps for option ROMs (the very first 1981 PC BIOS did not scan for them). (IBM PC / XT BIOS ROM scan)
Checked live on this page:
- checking…
The show & the cast
MODEL Season one of Halt and Catch Fire (AMC, 2014–2017) is set in 1983 Dallas: a salesman (Joe MacMillan), an engineer (Gordon Clark) and a young coder (Cameron Howe) at the fictional Cardiff Electric reverse-engineer a PC BIOS and build a portable they call the Giant.
MODEL ROXY flips one byte in the dump and the checksum goes red. Patch the last byte and it goes green again. The ROM here is original filler bytes, not IBM code.
Original pixel cast on this page MODEL
Made-up characters who stand in for roles. They are not the show's characters, and no show art, logos, likenesses or dialogue are used. The show and character names appear only as text references.
Improvement loop · ARTIST+CRITIC
MODEL ARTIST changes the look (pixel block size, scanlines, palette snap, CRT curve, exposure, phosphor glow) and CRITIC renders a 128×96 test frame, reads its pixels and scores five things: palette fidelity, contrast, scanlines, exposure and pixel blockiness (weights come from this page's seal). A change is kept only if the score goes up. LIT Scores are measured from pixels, never guessed, and the page throws if the best score ever goes down or doesn't reproduce.
params:
Gallery
Exports
WALL Nothing here goes online: the modems, boards, networks and markets are simulations. No real BIOS or ROM code is included. Show footage and art are not reproduced by design. AMBER facts are sourced but approximate.
proving…
Seal sha256(name|slug|blurb): 21e20fd472ea0c5ddd47cbe57cf5e50868d3438f8f0cc41d098311b244af6b9c · written to seals/hacf-02-rom-checksum.dlw only if missing