Microcomputer with self-test of macrocode
US4797808A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 1981 |
| Grant date | Jan 10, 1989 |
| Priority date | — |
| Expiry date | Jun 22, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F11/2273
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A microcomputer device contains a CPU with an arithmetic/logic unit and data/address registers on a single semiconductor integrated circuit having on-chip macrocode and microcode storage. A macrocode word is fetched from an on-chip ROM and stored in an instruction register in the CPU, then a sequence of microcode words is fetched from the microcode store based on this macrocode word. A check-code based on some function of all macrocode bits is stored in on-chip ROM upon manufacture. To test a device after fabrication is complete, a test program (resident in ROM or downloaded into on-chip RAM) is executed to address all bytes of macrocode and perform some cummulative function on it via the ALU to see if the same check-code is produced. If so, an output indicates a good unit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.