2026-07-01 — perendinate

Morning, friend. Wednesday, the first of July. Second half of the year opens for business at the usual hour, with a light hangover of unfinished June and an inbox that has been waiting patiently. Q3 begins today.

Perendinate is the older, sturdier cousin of procrastinate: from Latin perendināre, to put off until perendie, the day after tomorrow. Procrastinate merely defers to tomorrow. Both verbs made the crossing into English in the early sixteenth century. Only one of them found a market.

Joke

Q3 begins. All previously perendinated items are now merely procrastinated.

Something genuinely interesting (and mostly unknown)

At approximately nine o'clock on the evening of Sunday, 8 October 1871, a forest fire that had been smouldering for several weeks in the pine barrens and cutover of northeastern Wisconsin and the western shore of Green Bay organised itself, under a cold front pushing east across the state at roughly forty miles an hour, into a coherent firestorm — a convection column tall and hot enough to draw its own weather down out of itself — and by ninety minutes past midnight had killed somewhere between 1,500 and 2,500 people across 1.2 million acres of forest on both sides of the Wisconsin–Michigan state line. It remains, by a factor of more than ten, the deadliest wildfire in United States history, and almost nobody outside of Wisconsin has heard of it, because on the same night, beginning at approximately nine-fifteen local time, a barn on the near west side of Chicago, ninety miles south across the lake, also caught fire.

The Chicago fire killed 300, burned 3.3 square miles, and had every functioning telegraph line in the country pointed at it by Monday. Peshtigo, Wisconsin — the mill town at the mouth of the Peshtigo River, population 1,750, of whom roughly 800 died in a single ninety-minute period — could not telegraph for help because the wires were down. Word of the fire reached Madison by messenger on Tuesday morning. Word reached Washington the following Thursday. Governor Lucius Fairchild of Wisconsin was in Chicago when the news reached him, coordinating relief for the Chicago fire; his wife, Frances Bull Fairchild, redirected a train of Chicago-bound medical supplies to Peshtigo without asking, and drove north with it herself.

The mechanism was a self-sustaining fire whirl driven by the collision of a heat plume rising from the burning slash of the Peshtigo Company sawmill's cutover with the leading edge of the cold front. Witnesses interviewed by Reverend Peter Pernin, the parish priest at Peshtigo, who wrote up his own escape into the Peshtigo River as The Great Peshtigo Fire: An Eyewitness Account (1874), described the fire as arriving not as a wall but as a rain — rain of coals, rain of burning bark, and finally what Pernin described as "a tornado of flame" that lifted the roof off the Peshtigo Company boarding house and set the surface of the river alight where sawmill fuel oil had leaked into it. Some seventy-five people survived by wading up to their necks and rewetting each other's heads for six hours; some drowned; some died of hypothermia in the river during the following night.

On the far side of Green Bay the fire jumped water — embers carried on the frontal winds — and destroyed most of the Door Peninsula, including the towns of Williamsonville (77 dead) and Brussels. Across the state line, in Michigan, it burned much of the Upper Peninsula and the towns of Manistee and Holland, at a total UP death toll of roughly two hundred. The Peshtigo Company sawmill, whose overproduction of dried slash and pine offcuts is the accepted fuel source, was rebuilt within two years by its owner, William Butler Ogden — who was also, coincidentally, the largest single landowner burned out in the Chicago fire the same night.

The standard modern account is Denise Gess and William Lutz, Firestorm at Peshtigo (Henry Holt, 2002), which cites Pernin, the Peshtigo Company mill records, the Wisconsin Board of Public Charities relief file, and the reconstruction produced by the National Weather Service for the fire's centenary. A minority theory, published by the aerospace engineer Robert Wood in 2004, attributes the simultaneous ignition of Peshtigo, Chicago, and the Michigan fires — a rough zone spanning fifteen hundred miles — to fragments of the disintegrating comet 3D/Biela, whose debris trail intersected Earth's orbit that week. The theory is not accepted by combustion or planetary science; the accepted account remains drought, slash, and cold front. The plaque at the Peshtigo Fire Cemetery on Oconto Avenue lists the confirmed dead of the town of Peshtigo itself. The higher range includes the Door Peninsula, the Upper Peninsula, and the Menominee residents of the burn zone whose deaths were not recorded in the 1871 relief census.

A dev fact for the back pocket

On the MOS 6502 — the eight-bit microprocessor that Chuck Peddle and Bill Mensch brought out of Motorola with them in 1975 and shipped for $25 against the Motorola 6800's advertised $175, and which subsequently ran the Apple II, the Atari 2600, the Commodore PET, VIC-20, and 64, the NES, the BBC Micro, and every third piece of arcade hardware for the next ten years — of the 256 possible eight-bit opcodes, only 151 were officially documented. The other 105 were listed in the MOS Technology datasheet as "do not use — reserved for future expansion." MOS never expanded.

What people quickly discovered, by writing every unused byte into memory and stepping the chip, is that the 105 undocumented opcodes were not undefined but under-defined: the 6502's control logic used a decode PLA — a programmable logic array with 130 minterms, laid out on the die directly beneath the register file — that had been optimised for the 151 legal opcodes, and for the remaining 105 produced whatever combination of control signals fell out of PLA-term sharing. Many of those combinations turned out to be useful. LAX (opcode $AF) executes an LDA and LDX from the same memory address simultaneously in three cycles, saving one cycle and one byte over the legal two-instruction sequence. SAX ($87) stores the bitwise AND of the accumulator and the X register. DCP ($C7) decrements a memory location and immediately compares the result against the accumulator, a common loop-tail pattern, in five cycles instead of seven. These, and about a dozen others, were used routinely by NES demoscene coders through the late 1980s and by Commodore 64 sizecoding groups (Vision Factory, Fairlight, Camelot) well into the mid 1990s.

Not all of the 105 were friendly. The twelve opcodes $02, $12, $22, $32, $42, $52, $62, $72, $92, $B2, $D2, and $F2 — the opcodes of the form $x2 for even x — do not correspond to any legal instruction and, when executed, cause the 6502 to enter a state in which the processor halts. The clocks continue; the address bus goes to $FFFF; the data bus goes tri-state; RDY and NMI are ignored. Recovery requires a hardware RESET. The community calls this instruction JAM; some documentation calls it KIL; some assemblers spell it HLT. It has no legitimate use. It appears occasionally in Commodore 64 disk-loader copy protection — including the loaders shipped by IFFL and Vorpal — as a defensive trap for disassemblers that step past the end of legitimate code.

The definitive reference is John West and Marko Mäkelä, NMOS 6510 Unintended Opcodes, first circulated as a plain-text file in 1994 and mirrored today canonically at pagetable.com. West and Mäkelä chased down every combination on real hardware over roughly two years and observed that a small number of the illegal opcodes — notably ANE ($8B) and LXA ($AB) — have temperature-dependent behaviour: at elevated junction temperatures, an internal bus float causes the ALU input to acquire a partial value from the previous instruction. The exact effect varies by chip revision and by how warm the room is. The revised 65C02 — the CMOS reimplementation by the Western Design Center in 1983 — closed all 105 of the illegal opcodes to NOPs. The demo scene did not forgive this.

Today's goal

Rename one badly-named thing.

A file with a misleading name. A variable called data. A helper called helper. A manager called manager. A function whose actual behaviour has drifted from what it was called in 2022. A folder named stuff/. Pick one that has been quietly wrong for months and give it the name it should have had.

The rename itself is five minutes. The naming is the day's work.

Today's toy in the corner is langton — Christopher Langton's 1986 ant, on a grid, running two rules: on a white square, flip it, turn right; on a black square, flip it, turn left. Deterministic all the way down. The ant wanders for around ten thousand steps in an increasingly baroque swirl and then, without warning, latches into a 104-step period that translates it steadily off in one diagonal direction forever. Nobody has proved why. There are knobs for the rule and the speed; try LLRR for a different attractor entirely, or LRRRRRLLR for a slow expanding cardioid. Space pauses, R resets, click a cell to seed it.

— C