Specifications for Monroe 1655

Manufacturer: Monroe Division of Litton Business Systems
Model Number: 1655
Serial Number: Two Units in Museum
#1: E 915193
#2: E 916836
Date of Manufacture: #1: Mid 1970
#2: Late 1970
Manufactured In: USA
Original Price: $3,250 at introduction
Weight: 12 1/2 Pounds
Size: 12 1/2" Wide, 12 1/2" Deep, 6" High
Power Requirement: 60 Watts, 115V AC, 60Hz
Display Technology: Nixie Tube, Burroghs
10 Digits Mantissa, 2 Digits Exponent.
Special +/- Nixie for mantissa & exponent sign
Neon indicators for Overflow & Error condition
Logic Technology: Computer Design Corp. First-Generation "HTL" LSI Chipset
Chipset Fabrication by AMI
Logic contained two plug-in circuit boards
MOS Mask-Programmed ROM for microcode
Digits of Capacity: Internal: 14 Digits Mantissa + 2 Digits Exponent
Displayed: 10 Digits Mantissa + 2 Digits Exponent
Decimal Modes: Automatic Floating Decimal
Switch selectable normal or exponential notation
Automatic switching from normal to exponential mode
Arithmetic Logic: Algebraic
Math Functions: Comprehensive compliment of engineering math functions
Constant: None
Memories: 10 accumulator registers
Registers 7, 8, and 9 are working registers
Programmable: Yes, Learn Mode (LEMP)
128 Step Base Capacity
Additional 128 steps optional
Both units have 256 step capacity
Six Level Subroutine Nesting
Extensive Test & Branch Capabilities
Punched Card programming allows access to low-level microcode instructions/subroutines

Sincere thanks to Mr. David Lammi for donation of Monroe 1655 Serial #E 915193, along wtih CR-1 card reader and dust covers.

Tech Data [HTL Processor Instruction Set]

Previous Machine: Sharp QT-8D
Next Machine: SCM Cogito 412

Related Machines: Compucorp 120
Compucorp 122E
Compucorp 140
Monroe 1860

Advertising: Monroe 1655
Monroe 1655 Spec Sheet


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