Microcomputer with internal selection of on-chip or off-chip access
US4580216A · kind A · utility
20Cited by
7References
12Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 22, 1981 |
| Grant date | Apr 1, 1986 |
| Priority date | — |
| Expiry date | Jun 22, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/26
- 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. In the normal single-chip operation mode, a macrocode word is fethched from 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. In another mode, such as used for self-test employing a check-code, the device loads macrocode from external into on-chip RAM then executes from RAM to perform the desired routine, switching modes of operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.