BUILT-IN MICROPROCESSOR TYPE MEMORY CONTROLLING STRUCTURE

摘要

PURPOSE: To execute flexible byte collection at a microprocessor level by providing the memory control structure with a programmable byte collecting function. CONSTITUTION: A CPU 102 has 32-bit word size, 16-bit half word size and 8-bit byte size. An external memory bus 114 has various control signals for controlling a transaction or the like on the bus and can be accessed from the outside of, a chip 100. A bus interface unit(BTU) 104 has a logic circuit 116 for byte collection, and when a bus reading transaction is started, an input signal is validated and byte collection is executed. A flexible option can be set up in a DRAM control circuit 120 so as to use a DRAM having various access speeds and an automatic waiting condition generator (AWC) 118 independently controls processor instructions in a PROM 108 and the address space of I/O data. The AWC 118 can be invalidated.