Monroe Programmable Electronic Calculator (1785)

Rick Bensene rickb at
Fri Feb 29 10:25:29 CST 2008

> Monroe made several type of programmable calculators most of them were 
> rebadged Compucorp's.
> Based on the Compucorp HTL-chipset (a very sophistycated bit-slice design), 
> memory is mostly static ram i2102.
? Several types are displayed  the oldcalculator website from Rick Bensene.

The 1700-series Monroe/Compucorp calculators is one that I don't have a lot of information about, but I know that they did use a very sophisticated microprocessor-like (not bit-slice) architecture, based on the later ACL chipset, which was an improvement over the earlier HTL chipset.  

The machines used IC-ROM-based microcode, and dynamic RAM (not static like the 2102) for main memory.  The microcode determined the various functions available in the machine.  Programmable and non-programmable models were available.  Functionality depended on the ROM board which contained the microcode, the keyboard, and whether or not the machine contained expanded RAM. 

The Compucorp-designed machines of this timeframe were very advanced, and had it not been for Hewlett Packard coming out with even more advanced (albeit larger) calculators like the 9810, 9820-series, and the 9830, then later the handheld units like the HP-35, 45, and 65, Compucorp had, for a time, a good share of the high-end calculator marketplace along with HP's earlier machines (9100A, 9100B), and Wang's calculators.

For the story of Compucorp and its machines, see my website essay at

Rick Bensene
The Old Calculator Museum

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