Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US07/030,786external-prioritypatent/US4901234A/en
Application filed by IbmfiledCriticalIbm
Publication of MY103220ApublicationCriticalpatent/MY103220A/en
A COMPUTER SYSTEM IN WHICH PERIPHERALS GREATER IN NUMBER THAN THE NUMBER OF DMA CHANNELS PROVIDED IN THE SYSTEM CAN ALL HAVE DMA ACCESS. SOME OF THE DMA CHANNELS ARE DEDICATED TO CERTAIN ONES OF THE PERIPHERALS, WHILE OTHERS, TERMED "PROGRAMMABLE" DMA CHANNELS, ARE SHARED BY REMAINING ONES OF THE PERIPHERALS. EACH PERIPHERAL HAVING DMA ACCESS HAS A CHANNEL PRIORITY VALUE. WHEN A PERIPHERAL WANTS DMA ACCESS, IT TRANSMITS ITS CHANNEL PRIORITY VALUE ONTO AN ARBITRATION BUS. THE WINNING CHANNEL PRIORITY VALUE IS THEN COMPARED WITH PRESTORED DMA CHANNEL ASSIGNMENT VALUES. IF THE COMPARISON IS SUCCESSFUL, THE CORRESPONDING PERIPHERAL IS GIVEN A DMA CHANNEL CORRESPONDING TO THE DMA CHANNEL ASSIGNMENT VALUE WITH WHICH THE COMPARISON WAS SUCCESSFUL.(FIG 1)
MYPI88000196A1987-03-271988-02-26Computer having programmable dma control
MY103220A
(en)