UPD77017 datasheet(17/60 Pages) NEC

17 / 60 page

µPD77015, 77017, 77018

2.2

Program Control Unit

Program control unit controls not only count up of program counter in normal operation, but loop, repeat,

branch, halt and interrupt.

In addition to loop stack of loop 4 level and program stack of 15 level, software stack can be used for multi-

loop and multi-interrupt/subroutine call.

The

µPD77017 has external 4 interruptions and internal 6 interruptions from peripheral, and specifies interrupt

enable or disable independently.

The HALT and STOP instructions cause the

µPD77017 to place in low power standby mode.

When the HALT instruction is executed, power consumption decreases. HALT mode is released by interrupt

input or hardware reset input. It takes several system clock to recover.

When the STOP instruction is executed, power consumption decreases. STOP mode is released by hardware

reset input. It takes a few ms to recover.

2.3 Operation Unit

Operation unit consists of the following five parts.

– 40 bits general register

× 8 for data load/store and input/output of operation data

– 16 bits

× 16 bits + 40 bits → 40 bits multiply accumulator

– 40 bits Data ALU

– 40 bits barrel shifter

– SAC: shifter and count circuit.

Standard word length is 40 bits to make overflow check and adjustment easy, and to accumulate the result

of 16 bits

× 16 bits multiplication correctly.

2.3.1

General register (R0 to R7)

The

µPD77017 has eight 40 bits registers for operation input/output and load/store with memory. General

– R0L to R7L (bit 15 to bit 0)

– R0H to R7H (bit 31 to bit 16)

– R0E to R7E (bit 39 to bit 32)

But each of RnL, RnH and RnE are treated as a register in the following conditions.

(1) General register used as 40 bits register

General registers are treated as 40 bits register, when they are used for the following aims.

(a) Operand for triminal operation (except for multiplier input)

(b) Operand for dyadic operation (except for multiplier and shift value)

(d) Operand for operation

(e) Operand for conditional judge

(f)

Destination for load instruction (with sign extension and 0 clear)

Head room

SSSSSSSS

Result of multiplication among two's complement data

UPD77017 Datasheet(PDF) 17 Page - NEC

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