System ROM including a flash EPROM and a ROM for storing primary boot code replacing a block flash EPROM
US6182187A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 7, 1993 |
| Grant date | Jan 30, 2001 |
| Priority date | — |
| Expiry date | Apr 7, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/4403
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A computer system having a system ROM comprising a flash or bulk EPROM replacing a block flash or boot block EPROM, and a second ROM to store the primary boot code. In a first embodiment, a single block EPROM is replaced with a bulk EPROM and a ROM, where the ROM is preferably a one-time programmable ROM. The primary boot code is copied into the ROM thereby preventing its erasure. The bulk EPROM is reprogrammed if desired. Separate decode logic detects an address to the primary boot code and enables the ROM. In a second system using a block EPROM and a bulk EPROM as the system ROM, the block EPROM is replaced with a bulk EPROM, and the primary boot code is copied into both bulk EPROMs, preferably at mirrored locations. An external switch is provided with appropriate logic, so that the user may select between either of the bulk EPROMs to boot the system. Thus, if the system is unable to boot from one of the bulk EPROMs, the user may flip the switch to access the primary boot code from the other bulk EPROM. A software program is executed after successful reboot to reprogram and verify the contents of both of the bulk EPROMs. The software reprograms and verifies one bulk EPROM and the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.