| 摘要 |
Address generators output addresses of transfer data of transfer origin and destination DRAM's. Updating of the transfer addresses from the address generators during execution of DMA is performed based on a CAS signal from a timing signal generator. A delay element delays the CAS signal by a time which is the sum of an access time of the transfer origin DRAM and a data set-up time of the transfer destination DRAM. A transfer data counter counts the number of leading edges of the CAS signal while a RAS signal from the timing signal generator is held active. When a counted value reaches a preset value, the transfer data counter outputs continuous data transfer suspension information to the timing signal generator. With this arrangement, the halt in operation of a CPU due to continuous occupation of a bus is effectively prevented while achieving the increased data transfer rate. <IMAGE> |
