INTRODUCTION
1.2 MSM80C154S/MSM83C154S Features
•Full static circuitry
•Internal program memory (ROM)
16384 words ⋅ 8 bits (MSM83C154S)
•External program memory (ROM) Connectable up to 64K bytes
•Internal data memory (RAM)
256 words ⋅ 8 bits
•External data memory (RAM) Connectable up to 64K bytes
•Four sets of working registers (R0 thru R7 ⋅ 4)
•Stack
Free use of
•Four input/output ports
•Serial ports (UART operation)
•Six types of interrupts
(1)Two external interrupts
(2)Three timer interrupts
(3)One serial port interrupt
*Priority allocated interrupt processing
*
•CPU power down function
(1)Idle mode: CPU stopped while oscillation continued. (Software setting)
(2)PD mode: CPU and oscillation all stopped.
(Software setting)
(Setting I/O ports to floating status possible)
(3)HPD mode: CPU and oscillation all stopped.
(Hardware setting)
(Setting I/O ports to floating status possible)
•CPU power down mode cancellation
(1)Execution commenced from address 0 by CPU resetting. (IDLE, PD, and HPD mode cancellation)
*RESET pin is used
(2)Execution from interrupt address by interrupt request, or execution resumed from next address after the stop address. (IDLE and PD mode cancellation)
*External, timer, and serial port interrupts
•I/O control registers (0F8H)
b0: Port 0, 1, 2, and 3 floating setting (PD, HPD)
b1: Port 1 high impedance input port setting
b2: Port 2 high impedance input port setting
b3: Port 3 high impedance input port setting
b4: Port 1, 2, and 3
b5: Serial port reception error detector bit
b6:
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