System and method for mode switching
US5467435A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 1992 |
| Grant date | Nov 14, 1995 |
| Priority date | — |
| Expiry date | Nov 16, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2215/0065
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A host computer and printer and method of operation wherein the printer is able to switch between two modes of operation. When the printer is powered up, it initializes its internal data registers and printer memory, followed by a check to see if additional firmware, in the form of a cartridge or the like, is added to the printer. If additional firmware is present, the printer turns operational command over to the additional firmware. The present invention, residing in the additional firmware, stores a complete image of the printer state, internal registers, and memory in a location that cannot be accessed by either mode of operation. The present invention compresses the data so that the complete image of the printer state, internal registers, and memory occupies approximately eight KBytes of memory. The storage location may be part of the printer memory itself, or any other suitable location. The additional firmware then returns operational control to the original firmware within the printer thus allowing the printer to operate in the first mode of operation. The host computer may cause the printer to switch to the second mode of operation by simply overwriting the internal data r…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.