Read-only-memory for electronic calculator

Details Read-only-memory for electronic calculator Read-only-memory for electronic calculator

1973-09-24

1976-01-20

Shaw, Gareth D.

Communications: electrical

Digital comparator systems

3401725, 340173SP, G11C 1300

Patent

active

039342336

ABSTRACT:
A read-only-memory for use in an electronic calculator or the like, implemented in a large-scale-integrated MOS semiconductor chip. The ROM is designed to save area on the chip by employing a virtual ground feature and conserve power by a precharge system. The memory cells are in an array defining X and Y lines, with the presence or absence of a bit being determined by thin oxide under an X line between adjacent Y lines. Ground lines are provided for groups of Y lines, and the Y-decode matrix includes an arrangement for connecting a selected Y-line to a non-adjacent ground line. Only the X decode section is precharged rather than all the X lines. The entire decode and read out is accomplished in a small part of the instruction cycle of the calculator.

REFERENCES:
patent: 3680061 (1972-07-01), Arbab et al.
patent: 3703710 (1972-11-01), Kubo et al.
patent: 3721964 (1973-03-01), Barrett et al.
patent: 3740730 (1973-06-01), Ho et al.
patent: 3742592 (1973-07-01), Rizzi et al.
patent: 3744036 (1973-07-01), Frohman-Bentchkowski
patent: 3786437 (1974-01-01), Croxon et al.
patent: 3803554 (1974-04-01), Bock et al.
patent: 3806896 (1974-04-01), Mar

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