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SubjectRe: [comphist] Re: Microsoft and Xenix.
Rob Landley <>:
> On Monday 25 June 2001 16:19, wrote:
> > I learnt my computing on a PDP8/E with papertape punch/reader, RALF,
> > Fortran II, then later 2.4Mb removable cartridges (RK05 I think). toggling
> > in the bootstrap improved your concentration. Much later you could
> > get a single chip(?) version of this in a wee knee sized box.
> "A quarter century of unix" mentions RK05 cartridges several times, but never
> says much ABOUT them.
> Okay, so they're 2.4 megabyte removable cartridges? How big? Are they tapes
> or disk packs? (I.E. can you run off of them or are they just storage?) I
> know lots of early copies of unix were sent out from Bell Labs on RK05
> cartidges signed "love, ken"...

Ah, the memories... (apologies for the interruptions, but just had too ...)

RK05 cartriges looked very similar to a floppy case the size of an old 78 RPM
record (about 12 inches across, 2 - 3 inches high). I never used them, but
I did see them. They were among the first disk drives DEC ever made. Not the
first (I think that was a DF-32 for PDP 8 systems with 32 K bytes of disk
space). The raw storage was reported as 2.5 MB, formatted was ~2.4MB, with
two recording surfaces. The drive looked very similar to a modern CD drive
that would fit in about a 3U (ummm 4U?) 19 inch rack. It had 2 recording
surfaces. It did have a write enable/disable switch. If I remember right
these were originally made for the PDP 11/10-20 systems used for laboratory
device control - chromatographs were mentioned by the chemistry department
back in school.

I may have an old DEC peripheral specification book at home (11/45 version).
I really liked those books that DEC used to put out. If you ever needed to
program a DEC interface, that book had everything. It was almost like the
engineers were bragging about how easy the interfaces were to program.

> What was that big reel to reel tape they always show in movies, anyway?

I think they were CDC transports.

> I need a weekend just to collate stuff...
> > One summer job was working on a PDP15 analog computer alongside an 11/20
> > with DECTAPE, trying to compute missile firing angles. [A simple version of
> > Pres Bush's starwars shield].
> Considering that the Mark I was designed to compute tables of artillery
> firing angles during World War II... It's a distinct trend, innit? And the
> source of the game "artillery duel", of course...

Or the 11/34 version of the Lunar Lander (load from paper tape, graphics
display on VT11 - 512x512 8 bit color). It used to be distributed as a
diagnostic tool (hardware level interrupts, dual A/D conversion via joystick,
I/O via VT11). Any memory, DMA, or bus configuration errors would hang
the system with a known diagnostic one-liner message explaining the problem.

I also saw a report of a "terminal warfare" event where the graphics display
was being used for text editing when two little stick figure men would walk
onto the display, pick up a line, and then walk off the screen. There was
nothing the user could do until it finished. The text buffer wasn't touched,
only the display buffer.

Jesse I Pollard, II

Any opinions expressed are solely my own.
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