On Mon, Jul 9, 2018 at 1:23 AM Theodore Y. Ts'o <
tytso@mit.edu> wrote:
There were multiple OS's for the PDP-8 and PDP-15.
Right. You can find them on the PDP-8 web sites for instance. Check out sigh or better yet the PiDP-8 which I have running at with 4 OS loaded into the ROMs. The RIM loader can be loaded from the toggle switches for the purist, but the Pi will do it for you on power up if you like and don’t want the tedium.
I used on the
PDP-8/i was the 4k disk monitoring system, so named becasue it only
required 4k of 12-bit wide core memory.
Right I believe that was the first widely available OS and described in the small computer handbook. Remember mini (as in minicomputer) was term Gordon coined to mean minimal computer.
The resident portion of the
OS only required 128 12-bit words, loaded at octal 7600, at the top of
the 4k memory. It could be bootstrapped by toggling in 4 (12-bit
wide) instructions into the front console which had about 24 binary
switches[1].
[1] https://www.youtube.com/watch?v=yUZrn7qTGcs
The OS was distributed on paper tape, which was loaded by toggling in
18 instructions of the RIM loader, which was then to load the BIN
loader from paper tape into core memory. The RIM loader was designed
to be simple and easy to toggle into the console. (ROM? EPROM? We
don't need no stink'in firmware in read-only memories!) The BIN
loader could read in a more effoiciently packed data stored in punched
paper tape. The BIN loader would then be used to load the disk
builder program which would install the OS into the DF-32 (which
stored 32k 12-bit words on a 12" platter).
rIght and the RIM loaded was printed on front panel of the console. btw the disk was 19” in diamete. Danny Klein has the original disk platter from the one of the original PDP-8 - before marriage it used to hang in his living room. FYI that was the system at the computer museum from the EE Dept after it died in approx ‘75 I was there the disk crashed.
Later PDP-8's would run more a sophisticated OS, such as OS/8, which
had a "Concise Command Language" (CCL) that was designed to be similar
to the TOPS-10 system running on the PDP-10. OS/8 was a single-user
system, though; no time-sharing!
Be careful grasshopper. TSS/8 is available on those web sites although I admit it does not run on my PiDP-8 and I have not figured why (Something is corrupt and I have not spent the time or energy to chase it). Anyway, TSS/8. Supported 4-8 ASR-33 terminals, each had 4K words as you described before. There was assembler, basic, focal, Fortran-IV and an Algol circa 1965 extensions.
The PDP-15/30 that I used had a paper tape reader and four DECtape
units. It ran a background-foreground monitor. The background system
was what was used for normal program development. The foreground job
had unconditional priority over the background job and was used for
jobs such as real-time data acquisition. When the
background/foreground OS was started, initially only the foreground
teletype was active. If you didn't have any foreground job to
execute, you'd start the "idle" program, which once started, would
then cause the background teletype to come alive and print a command
prompt. So it was a tad bit more sophisticated than the 4k disk
monitor system.
RIght this is really the model for RT11 which would begat CP/M and last DOS-86 (aka PC-DOS, later renamed MS-DOS).