| 摘要 |
<p>PURPOSE:To replace a PROM with a mask ROM by switching a page address system and a batch address system according to applicable processing which is either data writing processing or data reading processing by a control signal to identify whether the applicable processing is the data writing processing or the data reading processing. CONSTITUTION:Control signals 13, 14, and 15 including a page designating address at the time of reading and the control signal at the time of writing are inputted from a control bus, the page designating address is outputted at the time of the reading by a switching control signal from a writing/reading control circuit 1, and the control signal is outputted at the time of the writing by the switching control signal. Processing to be executed is instructed by the control signal, an address system is switched according to the instruction, and an address can be designated by either taking in the page designating address from an input/output bus with the page address system at the time of the writing or taking in the control signal from the control bus as the address with the batch address system at the time of the reading. Thus, the PROM can be replaced with the mask ROM.</p> |
