Mmap was the only way to do disk I/O in Multics — we’re talking about a design a decade earlier than that. (Also you’re thinking of TOPS-10 — TOPS-20 and TWENE

Mmap was the only way to do disk I/O in Multics — we’re talking about a design a decade earlier than that. (Also you’re thinking of TOPS-10 — TOPS-20 and TWENEX were developed in the 70s. But your heart is in the right place!