Rom burst transfer continuous read-out extension method and a

Abstract

A microcomputer with a built-in ROM for a burst transfer method has a ROM divided into blocks, for reading data by being supplied with an address, a first control circuit for supplying the address to the ROM, an adder for adding a specific address value to the address and outputting an added address which is the result of the addition, a comparator for comparing the next supplied address and the added address and outputting the result of the comparison, a second control circuit for supplying a control signal indicating to the first control circuit that a burst transfer will or will not be executed, based on the result of the comparison output by the comparator, and a selector for selecting data output from each block and outputting the data to a bus. In the microcomputer, the address includes selection data for selecting any of the blocks, and the address and the added address are input to the blocks, so that data corresponding to the address or the added address is input in accordance with the selection data in the address. The selector selects and outputs the output data from the blocks in accordance with the selection data in the address. The first control circuit controls the timing of the supply of the address so that it is synchronized with the read-out timing of the ROM based on the control signal supplied from the second control circuit.