Microcomputer having ROM program which can be altered

Details Microcomputer having ROM program which can be altered Microcomputer having ROM program which can be altered

1995-05-25

1997-12-23

Shah, Alpesh M.

Boots, shoes, and leggings

39549701, 395375, 39518203, 3642328, 364245, 3642613, 3642685, 364DIG1, G06F 900

Patent

active

057015066

ABSTRACT:
A microcomputer whose ROM program can be altered without the necessity of rebuilding or remaking the ROM, wherein when an address outputted from a CPU to an address bus matches one of the addresses of locations at which the ROM program is to be altered, the ROM is disconnected from a data bus and a jump instruction op code is outputted to the data bus, followed by the start address of an altered contents stored in a RAM or the start address of an instruction for locating among a plurality of altered contents, the start address of the altered content that is substituted for the portion of the program to be altered; then, the CPU reads the jump instruction op code and the start address, the operand of the jump instruction, outputted on the data bus, and executes the jump instruction by which a jump occurs from the ROM program to the altered contents stored in the RAM to execute the altered contents, and control returns to the ROM program after the execution of each altered content, thereby altering the ROM program at a plurality of portions thereof.

REFERENCES:
patent: 4434464 (1984-02-01), Suzuki et al.
patent: 4573119 (1986-02-01), Westheimer et al.
patent: 5021951 (1991-06-01), Baba
patent: 5155829 (1992-10-01), Koo
patent: 5305460 (1994-04-01), Kaneko et al.
patent: 5325499 (1994-06-01), Kummer et al.
patent: 5448744 (1995-09-01), Eifert et al.
patent: 5454100 (1995-09-01), Sagane

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