> On Mar 1, 2026, at 4:32 PM, Steve Lewis via cctalk <[email protected]>
> wrote:
>
> Well, to clarify - my "amazement" was more the idea of developing OS
> software using paper (not as much the loading of one from paper, though
> that is still a "glad I didn't have to do that" thing :).
There's a nice description, I think in Gauthier van den Hove's thesis, of the
process used for the creation of the world's first full ALGOL 60 compiler, by
Dijkstra and Zonneveld. The two of them did this in about 6 months, which
included having to invent a number of core elements of parsing technology since
they did not exist yet.
They would sit at a table, assembly language coding form in hand. One of them
would propose the next line of code, the other would agree or they would
discuss it if needed, and repeat for the next line. Those forms were then
handed to punch operators to be converted into 5-channel tape punched in the
odd code that the assembler (also by Dijkstra, part of his Ph.D. thesis work)
could read.
Amazing stuff. Also amazing is that, after several years of production use,
only two wrong-code bugs were discovered, both for highly exotic cases.
> So I'd characterize early OS development (meaning like 1956-1961) as:
> developed "in memory" (e.g. CTSS is said to have been written in FAP/MAD),
> then the program exported to punch card (or punched tape-- fan tape being a
> bit later and fairly exclusive to the "DEC" ecosystem, as it were). Once
> verified "yeah this kind of works", maybe that code quickly migrated over
> to magtape (bearing it mind this was all pre-ASCII standards). But one
> would need some kind of "bootloader" to then initiate it from magtape.
Early PDP-11 software development was done on PDP-10 timesharing systems,
including running it in simulation (MIMIC -- a precursor of SIMH). The
resulting bits would then go to paper tape, I'm pretty sure, to be loaded into
the target machine. That might in fact be a paper tape only system, or if it
was RSTS it would have disks but the initial OS load would be paper tape.
Not all that long after, DECtape would typically be the OS distribution medium.
I'm not sure if those were created on PDP-10 systems; there was FILEX to do
that, but I don't know when that appeared.
By the time RSTS/E V5B arrived, development was on RSTS itself. I don't know
about V4A; system build (SYSGEN) used DOS, but it's hard to imagine people
doing software development on that sorry excuse for an operating system.
paul
