Hold Request Contention Resolver for Microprocessor System
Original Publication Date: 1980-Jan-01
Included in the Prior Art Database: 2005-Feb-13
In the system of Fig. 1, multiple direct memory access (DMA) devices DEV1-DEV4 contend with each other and with microprocessor PROC for access to the address and data lines of ADBUS. These contentions must be resolved by user-supplied logic for microprocessors and DMA devices, such as the Intel 8085 and 8257. RSLV1-RSLV3.1 are identical simple and cascadable circuits to resolve contention for the ADBUS in a first-come, first-served priority.