Monrobot : A trip down memory lane in the world of computers

Fred Cisin cisin at
Wed May 13 14:26:36 CDT 2020

A friend recently reminesced about the Monrobot, which we have discussed a 
little bit lately, . . .

[Note: Unrelated to the Marilyn Monroebot on Futurama]

---------- Forwarded message ----------
Date: Wed, 13 May 2020 16:38:22 +0000 (UTC)
Subject: A trip down memory lane in the world of computers   (I probably have
     shared this with you in the past)   from an email to another friend...

My high school... Erasmus Hall High School in Brooklyn...  Â
they were trying to exclude China and India at the time) was the first in 
NY City to get its own computer... in 1965.   IT was a Monrobot XI 2000.

Regarding that Monrobot XI  2000...     made by the Monroe desktop 
calculator company of that era...

Its main memory was a rotating magnetic drum, with 2K 
16 bit words of fast electronic storage. 
Cycle op time was 11 milliseconds. 

It used 16 bit words, and one wrote its machine language 
using what was NOT called "Hexadecimal", but instead "Sexadecimal" 
(Latin, not Greek prefix was used)  numbers, and NOT 1-9 then A-F, but 
rather 1-9 and then T-X. 

Storage was on punched paper tape.

I learned to program it so that I could optimize access to the rotating 
drum memory and get three accesses (the max possible) per revolution of 
the drum, as much as tripling memory access speed.

11 milliseconds means  100 cycles per second.   Modern desktop PCs 
operate at around 3,000,000,000 cycles per second.Compared to the 2,000 
words of main system memory of the Monrobot XI, today's desktop PCs have 
around 8 to 32 billion words of memory.

I programmed it  (at age 14, in 1965) in machine language (the computer 
teacher didn't know how to do that)  ... wrote a program for it to allow 
me to input and it to output to its printer a sequence of 3 strip tease 
images I got from a printout at Columbia University where I was then going 
to the Science Honors Program for high school kids, there. on weekends.

---------- Forwarded message ----------

I may be wrong about Erasmus Hall High School  of
Brooklyn being THE first high school in NY City to get its own
computer.   There is a reference elsewhere to Bronx High
School of Science kids being taught IBM 650 language in 1959
or so.

I suppose, if so, I could start splitting hairs and say that,
while the Monrobot XI and the IBM 650 were similar in many
ways, the Monrobot XI was a much more modern generation in
that it used solid state, where the IBM 650 used vacuum tubes.

I vaguely recall there may have been a Monrobot XI and a
Monrobot XI 2000, the latter having twice the system memory
(rotating magnetic drum) as the earlier model.

Those were the days.  I recall boot-strapping in programs in
machine language from the front panel!

I loved that machine.  I remember the delicious smell of the
high quality oiled paper tape! [Some paper tape was oil
impregnated, some was not).

The thing came with a Fortran compiler.  You loaded your
source tape on one tape reader, then loaded in part 1 of the
compiler, and an intermediate  tape was output.  Then you
loaded that intermediate tape and part 2 of the compiler on
the tape reader, and a compiled program paper tape was
output.   THEN you input the compiled program, and (if you
were very very lucky), it ran.

Everyone else including the teacher used Fortran ONLY.   I did
most of my programming on it in machine (not assembly... I
hand assembled my programs) ... machine language.

15 years later I programmed a prototype "Bio-medical micro
computer" that incorporated the JUST MONTHS EARLIER released
Intel 8080 processor to examine electrocardiograms in real
time (interrupt driven)  and identify abnormal beats.   I
programmed it in machine language, too.   Storing programs in
1702 EPROMs.   Input was via 3 buttons cycling 7 segment LEDs,
and a LOAD and RUN button.  And an analog input for the EKG
signal.    Output was to EPROM programmer and to EKG strip

Damn thing actually worked, pretty much.   As well as most
other efforts back in 1975, anwyay.


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