Method and apparatus for overriding a ROM routine in response to a reset
US5018062A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1987 |
| Grant date | May 21, 1991 |
| Priority date | — |
| Expiry date | Oct 23, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/32
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An electronic device comprising a state machine is coupled between the ROM and its socket. When armed by an arming sequence, the device responds to an address from a microprocessor during a reset operation to modify the output of the ROM. The modified output causes a jump to a routine in RAM rather than a jump in an initialization routine in the ROM. This enables a user to change the microprocessor's addressing mode from protected to real without a complete initialization of the system. Arming of the device and reset of microprocessor is caused by a protected mode routine, and after reset the mircroprocessor processes a real mode routine.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.