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FWD# 61159
Thu, 15 Mar 2007
Back in 197x, I played with several Monrobot Mark XI computers at Scotch College Melbourne. The "Computer Club" had a room in an old Army-style building with 2 Monrobot XI computers.
We started with one such computer, but when it broke down, we went looking for spare parts, manuals, expertise etc, and eventually collected 5 computers, another complete set of circuit cards and maintenance manuals.
We had a grand time, writing code in "sexadecimal", typing it in on the electric typewriter, saving programs to/from paper tape, repairing paper tape, playing blackjack and other games.
There was a higher-level language QUIKOMP http://www.mv.com/ipusers/xlisper/MonrobotXI.jpg and a Nmemonic Assembler, but it was generally simpler to just type in the Hex.
The Character set was based around the puched card data format " ",1-9 0 A-I J-R "/",S-Z Sexadecimal I/O used the characters 0-9, S, T, U, V, W, X (easy to map from punced card to 0-15).
Graham ??? tried to "network" two Monrobots together by cross-connecting I/O channels though a interconnect box that recognised certain characters as "push button X on the control pannel".
Our systems had extra half-cabinters on the end holding large 240V to 110V transformers. Internally the 110V AC was rectified and then fed to valves used to drive the parallel output devices.
The electric typewriters had extra mechanical soloenoids and combs underneath, which If you e.g. pressed a key while trying to unjam an electric typewriter, you could get ~150V DC through your fingers!
BRL 1961, MONROBOT XI, start page 0672
MONROBOT XI
Monroe Calculating Machine Mark XI
MANUFACTURER
Litton Industries
Monroe Calculating Machine Division
Photo by Monroe Calculating Machine Division
APPLICATIONS
The Monrobot Mark XI is a stored-program, general
purpose electronic business computer capable of
operation with a wide variety of input-output equip-
ment.
PROGRAMMING AND NUMERICAL SYSTEM
Internal number system Binary
Binary digits/word 32 including sign
Binary digits/instruction 16
Instructions/word 2
Instructions decoded 27
Instructions used 27
Arithmetic system Fixed point; programmed
floating point
Instruction type One address
Number range 0 to 231 - 1 or 0 to +- 109 or
0 to +- 2, 147, 483, 647
Instruction word format
+---------------+-----------------+
| 16 11 | 10 1 |
+---------------+-----------------+
| Instruction | Address |
+---------------+-----------------+
ARITHMETIC UNIT
Incl. Stor. Access Exclud. Stor. Access
Microsec Microsec
Add 9,000 3,000
Mult 34,000 28,000
Div 500,000 500,000
Division is programmed.
Construction (Arithmetic unit only)
Transistors 190
Diodes 1,675
Arithmetic mode Serial
Timing Synchronous
Operation Sequential
STORAGE
No. of No. of Average Access
Medium Words Digits Microsec
Magnetic Drum 1,024 32,768 6,000
INPUT
Media Speed
Punched Paper Tape 20 char/sec
Electric typewriter 10 char/sec
16-key numeric keyboard 10 char/sec
80-column card 16 col/sec
Teletypewriter 10 char/sec
The machine can accomodate any three of the above input
devices simultaneously. Punched paper tape may be any code, 5
to 8 level. Quoted input and output speeds include conversion
to and from binary as well as translation of any tape language
to machine code. Higher speeds are possible using pure binary
input and output.
OUTPUT
Media Speed
Punched Paper Tape 20 char/sec
Electric Typewriter 10 char/sec
80-column Card 16 col/sec
Teletypewriter 10 char/sec
The machine can accomodate any three of the above output
devices simultaneously. Punched paper tape may be any code, 5
to 8 level.
CIRCUIT ELEMENTS OF ENTIRE SYSTEM
Type Quantity
Tubes
5727 10 - 30 (10 tubes/output device)
Diodes
Primarily 1N636 2,300
Transistors
Primarily 2N412 383
CHECKING FEATURES
Parity check on input and output. Parity
may be omitted.
Action taken on parity failure depends upon program. With
Teletype or other parity-less codes, parity is not used.
POWER, SPACE, WEIGHT, AND SITE PREPARATION
Power, computer 0.850 Kw 0.940 KVA 0.9 pf
Volume, computer 48 cu ft
Area, computer 15 sq ft
Room size 10 ft x 10 ft
Floor loading 30 lbs/sq ft
100 lbs concen max
Weight, computer 375 lbs
System requires 15 amp, 110 volt, AC, 60 cps line.
PRODUCTION RECORD
Number produced to date 7
Number in current operation 6
Time required for delivery 6 - 9 months
COST, PRICE AND RENTAL RATES
Cost of computer with operator desk,
1 typewriter, 1 tape reader, and 1
tape punch $24,500
Additional Equipment
16-key numeric keyboard 300
Tape Reader 1,250
Tape Punch 700
Typewriter 2,350
Buffer for third device 600
Above prices are approximate.
Monthly rental of computer with operator desk,
1 typewriter, 1 tape reader, and 1 tape punch,
including service $700
Maintenance contracting is $1,200/year after
90-day service guarantee.
PERSONNEL REQUIREMENTS
Manufacturer makes a programmers' school available to users.
One operator is required for each 8-hour shift. Virtually no
operator training is required.
RELIABILITY, OPERATING EXPERIENCE,
AND TIME AVAILABILITY
Conservative solid-state design assures long life and wide
margins under all but the most extreme operating conditions.
Pluggable printed circuit boards provide trouble-free operation as
well as ease of maintenance. Monrobot XI operates with full
+-25% voltage margins at 110oF ambient.
ADDITIONAL FEATURES AND REMARKS
The Monrobot Mark XI accepts alpha-numeric information
in any code from up to three independent input devices and can
output information to any combination of three independent
devices.
System can simultaneously prepare independent output
documents in any format, and can merge transaction and
unit record input tapes in any format.
