Plummer, Dave
▶ Watch on YouTubeCore ideas
Plummer traces a self-taught path into computing that begins with an unsupervised TRS-80 at a RadioShack he biked to as an 11-year-old, through a Commodore 64 phase where he hand-wrote a Galaga clone in raw 6502 machine language (no assembler) and then accidentally destroyed his only backup by copying a blank floppy over it, to dropping out of high school almost imperceptibly — "there's no moment when I dropped out... you just go less and less and less" — and working night-shift jobs like 7-Eleven before a physically miserable gas-tank-dipping incident convinced him to talk his way back into school at 21. He funded his return to university by selling shareware (HyperCache, a disk cache for the Amiga) via mailed shareware registration cards, and got into Microsoft the same scrappy way: reading a book about Bill Gates, then cold-emailing every Microsoft employee he could find in his own customer registration stack until one, Alasdair Banks, connected him to a phone interview that led to a DOS-team summer internship. He describes Microsoft in that era as "the single most potent assemblage of smart people" he's encountered, credits Bill Gates's success to relentless singular focus plus hiring people smarter than himself, and offers granular technical color on the period: MS-DOS as fundamentally a 640K-limited command launcher (the "640K ought to be enough" quote is apocryphal), the A20-line trick for squeezing an extra 64K of high memory, and porting the entire Windows 95 shell to NT — including Unicode conversion, and a heated, ultimately-lost architectural argument about aligning ID-list byte lengths on MIPS that he still believes cost Windows measurable performance decades later.
Plummer supplies firsthand creation stories for several ubiquitous pieces of software. Task Manager began as a side project he wrote at home (unable to call internal APIs, so initially reading from the registry), rebuilt in-house with NtQuerySystemInformation calls once he had access, deliberately avoiding the C runtime entirely (saving ~96K by manually invoking C++ object constructors) to keep the original binary at 87KB, and using a self-devised Hamming-code-like dirty-bit scheme per row/column so only changed cells get repainted — a design still underlying today's multi-megabyte version, handling roughly two billion users a month. A recurring bug where Task Manager reported over 100% CPU usage was eventually traced (via a debug assert containing his home phone number, left in commented-out shipped source to this day) to a kernel accounting issue rather than his own code. He also built ZIP folder support (originally sold as shareware "Visual ZIP," acquired by Microsoft after a cold-call from an internal buyer who didn't realize he already worked there — he used the proceeds to buy a Corvette), ported Space Cadet Pinball to NT by treating the original assembly state-engine as an untouched black box wrapped in new C rendering code, and built Windows Product Activation for XP under a tight deadline after the original owner slipped the schedule. He and Lex spend a long stretch debating Windows' loss of user customizability (unmovable taskbar, dark-pattern "recommended settings" defaults nudging users toward Edge) — Plummer's view is that this is partly genuine engineering-complexity cost and partly a scheduling/craftsmanship problem, since UI that keeps getting rewritten under deadline pressure never accumulates the polish that comes from one owner caring about a component for years — while acknowledging a self-critical episode from his own shareware days, when his company Software Online was investigated by a state attorney general over nag-to-upgrade reminders and default paid disc-fulfillment, an experience he calls one of the scariest of his life and traces partly to his own autism-driven trouble anticipating how upsell tactics would be perceived by people who think differently than he does.
The second half of the conversation is a detailed, practical account of living and working with autism (and ADHD). Plummer describes monotropism — intense single-task focus with difficulty task-switching — as the core theory of autistic cognition, alongside a near-total blindness to others' unstated mental states ("I run a little proxy NPC game for everybody I deal with"), literal interpretation of language and figures of speech (a childhood incident involving his grandfather's "big enough to hold a horse"), and "masking" as the effortful, non-automatic performance of neurotypical social behavior. He offers concrete coping mechanisms he's developed: emotional post-processing (replaying past interactions afterward to identify what he missed, sometimes correcting the record years later, as when he emailed a car-restoration shop a decade after the fact to say he actually had been impressed with their work), explicit check-in rituals with his wife of 31 years to substitute for the intuitive emotional reads he can't make, and a "10-second autism test" (asking whether cooperation or creativity matters more to society, and a literal-vs-idiomatic "how many chairs are left" puzzle) as informal, error-prone but illustrative diagnostic heuristics. He argues that autism's association with excellent programmers comes from the same trait profile — obsessive drive to take things apart and understand what's inside, combined with singular focus — and that his best professional advice for autistic people is to "sell what you can do and not yourself," using portfolios and concrete work rather than personality-driven interviews. He closes on his current side projects (an RL agent, built with Lua for game-memory extraction and Python for a dueling Deep-Q network, learning to play the 1980 vector arcade game Tempest, on which he holds the world record; restoring PDP-11 minicomputers; and running "GitHub Primes," a long-running multi-language benchmark project comparing prime-sieve implementations across ~100 programming languages, currently topped by Zig) and a measured view of AI-assisted coding: useful as an accelerant and teaching tool for experienced programmers picking up new languages, but not yet capable of whole-cloth generating complex systems, with the programmer's future role shifting toward something like an architect assembling pre-built components rather than hand-writing individual lines.
Excerpts
On the moment he first understood the psychological mechanics of quietly dropping out of high school:
“There's no moment when I dropped out. You just go less and less and less until you realize it's going to be embarrassing if I show up because I haven't been there in a long time, and then pretty soon you're just not going, and that's how you drop out of high school. So, if you find yourself on that path, stop doing that.”
On building Task Manager to be small and reliable, and the debugging assert that carried his home phone number for years in shipped source code:
“I didn't want to link to the C runtimes at all... that saved me whatever the C runtime is, 96k or something... I finally put my phone number in the assert, and I was like, 'If you see this message, call DavePL at 425-836'... We were able to go through, and it was actually a kernel accounting issue... You'd think we would then remove my phone number, but we just commented it out, so it's shipped, and it's in all the damn source code leaks for NT that are out there.”
On why he doesn't think autism entails a lack of empathy, framed as a communication rather than a caring deficit:
“I don't know how you're feeling, so it's hard for me to be empathetic with it until you communicate to me what it is you're experiencing. And then once I know, once I have an understanding of what's going on in your head, I can feel incredibly sorry for you. But until then, I'm going to assume you're going to handle it just like I would in your position.”