National Semiconductor MM5799

MM5799 is a National Semiconductor microcontroller in the COPS I family.

data sheet from 1977 National MOS LSI Databook

The MM5799 has 1.5 K of 8-bit ROM and 96 4-bit nibbles of RAM. It was used in games like Mattel Basketball, Hockey and Soccer, as well as educational calculators like Quiz Kid Racer and Quiz Kid Speller.

In these games, the die is bonded directly to the PCB and protected with a plastic cover. That makes it easier to get die shots, although it's very easy to break the exposed bond wires. The marking on the die says MM4799 instead of MM5799.

Quiz Kid Racer

National Semiconductor educational calculator. It uses a DS8874 9-bit shift LED driver.

Patent with source and object code

hardware description and pinout

die shot

segment PLA Input on right, output on left

ROM array

raw ROM dump

ROM dump

source code warning- octal ahead

instruction decoder pic

instruction decoder decoded

full PCB

digits and operator LED under magnifying bubble

normal digit under magnifying bubble

equals sign under magnifying bubble

operators LED under magnifying bubble

digits and equals sign with magnifying bubble removed - note how equals sign LED is mounted lower

equals sign with magnifying bubble removed

operators LED with magnifying bubble removed

DS8874 clock and data signals - this is while it's flashing + - x /

Quiz Kid Speller

National Semiconductor educational calculator.

die shot

segment PLA Input on right, output on left

ROM array

raw ROM dump

ROM dump

LED driver, transistors and diode surface-mounted on PCB

DS8877 LED driver surface-mounted on PCB

transistor surface-mounted on PCB

another transistor surface-mounted on PCB - I'm guessing one is NPN and the other PNP. There's a 3rd that's not bonded.

diode surface-mounted on PCB

word list - this takes up pages 20-32 and part of page 33, plus quite a bit of code. MM5799 is not very efficient at this; it takes more than 1.5 bytes per letter!


Mattel handheld game.

top metal die shot - this game had the battery connected backwards, which vaporized some bond wires and metal, and deposited spall all over the die

top metal ROM array

top metal segment PLA Input on right, output on left

die shot with top metal removed - it cleaned up nicely

ROM array with top metal removed

segment PLA with top metal removed Input on right, output on left

raw ROM dump

ROM dump

simple MM5799 disassembler

MM5799 emulator work in progress

MM5799 info from CPU Shack

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