Microprocessor controller with automatic clock-rate switching
US5442774A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1993 |
| Grant date | Aug 15, 1995 |
| Priority date | — |
| Expiry date | Sep 16, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F1/08
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A printer controller employs a microprocessor together with an application-specific-integrated-circuit (ASIC) to manage the operation of the printer. Among its functions, the ASIC manages memory access for the microprocessor. Either fast- or slow-clock microprocessors may be installed in the controller, but the ASIC requires a slow clock. When a fast-clock microprocessor is installed, the ASIC must divide the clock frequency to provide its own (slow) clock. Likewise, the use of a fast-clock microprocessor requires the ASIC to insert memory-cycle WAIT times, whereas a slow-clock microprocessor needs no WAITs. In a preferred embodiment of the invention, provision is made, during initial power-on RESET, to inform the ASIC which clock speed is being used. This information is conveyed by the configuration of the WAIT interconnection between ASIC and microprocessor, thus eliminating the need for a dedicated ASIC pin for this purpose.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.