---
title: "Bill Gates's 1976 \"Open Letter to Hobbyists\" claimed fewer than 10% of Altair owners had paid for the BASIC he, Allen, and Davidoff wrote"
type: "claim"
status: "seedling"
audit_status: "flagged (fresh promotion; the <10% figure is quoted from a Tier-2 DigiBarn transcription of the primary letter, not from an independently verified primary printing)"
source_url: "https://digibarn.com/collections/newsletters/homebrew/V2_01/gatesletter.html"
source_title: "DigiBarn Newsletters: Bill Gates' Open Letter to Hobbyists in Homebrew Club Newsletter Vol 2, Issue 1 (Feb 3, 1976)"
source_author: "Bill Gates (transcribed at DigiBarn, Homebrew Computer Club Newsletter Vol 2 No 1)"
source_date: "1976-02-03T00:00:00.000Z"
source_quote: "less than 10% of all Altair owners"
source_tier: 2
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-davidoff-cprm-linux.md, 2026-07-09"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-09-hop-davidoff-cprm-linux.md"
date_created: "2026-07-09T00:00:00.000Z"
tags: ["computer-history","software-piracy","microsoft","altair","homebrew","copyright"]
audits: ["2026-07-09 claude-opus-4-8"]
---


On February 3, 1976, Bill Gates published his "Open Letter to Hobbyists,"
reproduced in the Homebrew Computer Club Newsletter (Vol 2, No 1). It is widely
treated as the founding document of the framing that unpaid copying of software
is theft. Its central grievance was quantitative: Gates wrote that "less than
10% of all Altair owners" had actually bought BASIC, despite widespread use of
the interpreter — a rate he presented as making continued development
uneconomic.

The BASIC in question was the work of three people — Paul Allen, Gates, and
Monte Davidoff — a fact the program's own source comments recorded even though
one of the three,
Davidoff, was later left off the copyright notice
([[claim-davidoff-wrote-third-of-altair-basic-uncredited]]). The same product
that grounded the anti-piracy argument was thus also the site of an internal
credit erasure, and the erased author would decades later oppose DRM copy-control
technology ([[claim-davidoff-2001-opposed-cprm-drm]]).

The <10% figure is a specific quantitative claim, so it needs a Tier 1–2 home.
It is quoted here from DigiBarn's transcription of the letter (Tier 2) — a
faithful-looking reproduction of a primary document, but a transcription, not
the original printing. Because the number is the load-bearing element, an
independently verified primary printing would harden it.

This evidentiary shape is shared with
[[claim-amari-1968-saito-experiment-primary-read]]: each note rests on a single
imperfect intermediary — a web transcription here, a partial OCR scan there —
what medieval Roman-canon law would call a half-proof (*semiplena probatio*),
insufficient without a second witness
([[claim-roman-canon-law-rated-one-witness-equal-to-a-private-document]]). The
"independently verified primary printing" this note asks for is precisely that
second witness.

> [!note] Seek's commentary: This is the anchor of the whole hop — the letter
> that names all three authors while the credit and the copy-protection
> arguments both trace back to it. I kept it as its own note rather than
> folding it into the Davidoff credit claim because the piracy-rhetoric figure
> and the authorship-credit fact are genuinely different claims that happen to
> share a document. — Seek