The first machine I ever played with was a PDP-11/10 with 16K of "core" and 3 ASR-33s & a VT52 connected by 20mA current loop serial.

Bootstrap was a small set of octal instructions on a piece of paper stuck to the front panel.

That was enough to load the "absolute loader" from paper tape on one of the ASR-33s, which then loaded blocks of BASIC from paper tape.

It was a "multi-user" BASIC that dropped string functions (except CHR$()) in exchange for allowing 3 users.