mitsubishi - Al Kossow's Bitsavers

MITSUBISHI MICROCOMPUTERSMS0740·XXX5 PSINGLE.CHIP a·BIT CMOS MICROCOMPUTERCPUSix registers,as shown in Fig. 2, are contained inside theCPU. Each Of these register is now described in turn.Accumulator AThe accumulator is the 8-bit register and is heart of themicrocomputer. Arithmetic and logic operations, transfersand processing of input/output and other data are performedcentering on this register.Index Register X·This is an 8-bit register. In the index addressing modewhere this register serves as the index register, the Contentsof this register and the contents of the program c:ounteris added and the result is actual address. When flag Tin the program status register is "1 ,It the contents of indexregister X become the other operand address.Index . Register VThis is also an 8-bit register. In the index addressing modewhere this register serves as the index register, the contentsof this register and the contents of the program counteris added and the result is actual address.7 0IA I Accumulator7 0IX Index register XI7 0yIndex register YII7 0SI I Stack pointer15 7 0PCHPCL I Program counterIIProcessor status registerCarry flagZero flagInterrupt disable flagDecimal mode flagBreak flagX-modified arithmeticmode flagOverflow flagNegative flagFlg.2Register configuration3-6 • . MITSUBISHI"'ELECTRIC