Digital Electronics: Principles, Devices and Applications

582 Digital ElectronicsT2/P1.0T2EX/P1.1P1.2P1.3P1.4P1.5P1.6P1.7RSTRxD/P3.0TxD/P3.1INT0/P3.2INT1/P3.3T0/P3.4T1/P3.5WR/P3.6RD/3.7XTAL2XTAL1234567891011121314151617181920V SS11 24DUALIN LINEPACKAGE4039383736353433323130292827262524232221VCCP0.0/AD0P0.1/AD1P0.2/AD2P0.3/AD3P0.4/AD4P0.5/AD5P0.6/AD6P0.7/AD7EA/VPPALEPSENP2.7/A15P2.6/A14P2.5/A13P2.4/A12P2.3/A11P2.2/A10P2.1/A9P2.0/A8Figure 14.17PIN connection diagram in the 40-pin DIP package.Instruction SetThe instruction set of the 80C51 family of microcontrollers consists of 111 instructions divided intofive categories, namely data transfer instructions, arithmetic instructions, logical instructions, Booleanvariable manipulation instructions and control transfer instructions.InterruptsThe 80C51 family of microcontrollers supports five vectored interrupts. These include external interrupt0, external interrupt 1, timer/counter 0 interrupt, timer/counter 1 interrupt and serial port interrupts.Power ModesThe 80C51 family of microcontrollers offers various operational modes that can be used to reducepower consumption. These include STOP CLOCK MODE which enables the clock speed to be reduceddown to 0 MHz, IDLE MODE when the CPU puts itself to sleep while all of the on-chip peripheralsstay active and POWER DOWN MODE in which the oscillator is stopped. In addition to the powersavingoperational modes, it also offers ONCE TM (On-Circuit Emulation) MODE which facilitatesin-circuit testing and debugging.14.5.1.2 80C31FA/8XC51FA/FB/FC (Dallas Semiconductor and Other Manufacturers)The same as 80C51 except for the size of ROM and RAM, which is 0K/8K/16K/32K (ROM) and 256bytes (RAM).