who here already worked with these ?

[Bill Campbell]

On Mon, Dec 14, 2009, Vu Pham wrote:
> You must be super geeks :)
>
> http://royal.pingdom.com/2009/12/11/retro-delight-gallery-of-early-computers-1940s-1960s/

The first computer I used was the Bendix G-20 which was a bit
after the G-15.  I learned FORTRAN on the G-20 when I was handed
a deck of cards with a program to debug, a copy of McGracken's
FORTRAN manual, and free access to the key punch and computer.

The G-15 used rotating drum memory and interleaving instructions
was important to be sure that the next instruction was read efficiently.

I think that the G-20 was the first commercial computer to use
interrupt driven I/O that could be overlapped with computation.

I did a bit of work on the IBM 7090 and 7094 machines.  Most of
this was on a 7090 at the U.S. Naval oceanographic office.  In
typical government ``efficiency'' they required I use the Navy's
machine instead of the Burroughs B-5500 time-sharing system as it
was ``cheaper'' for me to drive to the 7090, submit a job on
cards, go back later that day to pick up the output, and resubmit
it, repeat as necessary, than to run it from our office using a
ASR-33 teletype where the output would be back immediately (for
some definition of immediately give 110 baud TTY lines :-).  The
real kicker was that this job was analyzing sonar detection data
where it would read a tape make a set of calculations, write a
line to the printer, rewind the tape, and repeat for each
different analysis.  This ran overnight, and the night operator
killed the job several times because it was ``in a loop''.  I
finally had to go babysit the job to keep him from killing it
(more billable hours).

I'm surprised they didn't list the Burroughs B-5500 as it was
probably the first machine to use real virtual memory (IBM
invented thrashing later and called it VM).  It was also
interesting in that it had no assembly language, but its native
language was ALGOL.  Burroughs MCP (Master Control Program)
Operating System was vastly superior to IBM's OS/360 and its
successors (unless you consider job security for an army of IBM
support people to do things the OS should do).

Bill
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