• https://de.wikipedia.org/wiki/National_Semiconductor

The National MM5700 or National MM57XX series a family of 4-bit calculator chips designed by National Semiconductor. The chips were made using PMOS technology, most designed for 9V battery, had an a very limited set of math operations - some only as few as addition, subtraction, multiplication, and division. These chips were made as part of National attempt to enter the ultra-low-end calculator market.

• MAPS (MM570x) - National Semiconductor
• http://www.bitsavers.org/components/national/_dataBooks/1972_National_MOS_Integrated_Circuits.pdf

• Einzigartiges Rechenwerk: Olympia CD700 | Vintage Rechenmaschine
  • national semiconductors MAPS (Microprogrammable Arythmetic Processor System)
  • besteht aus
    • MM5700 - ALU (max. 750 kHz)
    • MM5701 - register
    • MM5702 - timing and control unit
    • MM5703 - control ROM (extension)
    • MM5704 - keyboard interface unit
    • MM5705 - control ROM
    • MM5706 - static Data Monitor