3.3.6 Push and Pop Instructions

There are instructions to push and pop the 16-bit registers AF, HL, DC, BC, IX, and IY. The registers AF', HL', DE', and BC' can be popped. Popping the alternate registers is exclusive to the Rabbit, and is not allowed on the Z80 / Z180.

Examples

POP HL

PUSH BC

PUSH IX

PUSH af

POP DE

POP DE’

POP HL’

3.3.7 16-bit Arithmetic and Logical Ops

The HL register is the primary 16-bit accumulator. IX and IY can serve as alternate accu- mulators for many 16-bit operations. The Z180/Z80 has a weak set of 16-bit operations, and as a practical matter the programmer has to resort to combinations of 8-bit operations in order to perform many 16-bit operations. The Rabbit has many new op codes for 16-bit operations, removing some of this weakness.

The basic Z80/Z180 16-bit arithmetic instructions are

ADD HL,ww

; where ww is

HL, DE, BC, SP

ADC HL,ww

; ADD

and ADD

carry

SBC

HL,ww

;

sub

and sub

carry

INC

ww

;

increment the register (without affecting flags)

In the above op codes, IX or IY can be substituted for HL. The ADD and ADC instructions can be used to left-shift HL with the carry. An alternate destination prefix (ALTD) may be used on the above instructions. This causes the result and its flags to be stored in the corre- sponding alternate register. If the ALTD flag is used when IX or IY is the destination regis- ter, then only the flags are stored in the alternate flag register.

The following new instructions have been added for the Rabbit.

;Shifts

 

 

RR

HL

; rotate HL right with carry, 1 byte, 2 clocks

 

 

; note use ADC HL,HL for left rotate, or add HL,HL if

 

 

; no carry in is needed.

RR

DE

; 1 byte, 2 clocks

RL

DE

; rotate DE left with carry, 1-byte, 2 clocks

RR

IX

; rotate IX right with carry, 2 bytes, 4 clocks

RR

IY

; rotate IY right with carry

;Logical Operations

AND

HL,DE

; 1

byte, 2 clocks

AND

IX,DE

; 2

bytes, 4 clocks

AND

IY,DE

 

 

OR HL,DE

; 1

byte, 2 clocks

OR IX,DE

; 2

bytes, 4 clocks

OR IY,DE

 

 

36

Rabbit 3000 Microprocessor

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Jameco Electronics 2000, 3000 manual Push and Pop Instructions, 7 16-bit Arithmetic and Logical Ops
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