668-0003-C Rabbit Semiconductor, 668-0003-C Datasheet - Page 39

• Manufacturer Part Number: 668-0003-C
• Description: IC CPU RABBIT2000 30MHZ 100PQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0003-C

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 2000 8-Bit
• Speed: 30MHz
• Voltage: 2.7V, 3V, 3.3V, 5V
• Mounting Type: Surface Mount
• Package / Case: 100-MQFP, 100-PQFP
• Features: -
• Other names: 316-1004; 668-0003

Some simplifications are possible if one of the unsigned numbers being compared is a
constant. Note that the carry has a reverse sense from
pseudo-code in the form
address pointed to by
the 16-bit unsigned integer
For signed integers the conventional method to look at the zero flag, the minus flag and
the overflow flag. Signed 8-bit integers span the range –128 to +127 (0x80 to 0x7F).
Signed 16-bit integers span the range –32768 to + 32767 (0x8000 to 0x7FFF). The sign
and zero flag tell which is the larger number after the subtraction unless the overflow is
set, in which case the sign flag needs to be inverted in the logic, that is, it is wrong.
Chapter 3 Details on Rabbit Microprocessor Features
;test for HL>B
LD DE,(65535-B)
ADD HL,DE
SBC HL,HL
BOOL HL
; HL>=B
LD DE,(65536-B)
ADD HL,DE
SBC HL,HL
BOOL HL
; HL>=B
LD HL,1
; HL<B B is a constant, not zero (if B==0 always false)
LD DE,(65536-B)
ADD HL,DE
SBC HL,HL
INC HL
;
; HL <= B B is constant not zero
LD DE,(65535-B)
ADD HL,DE
CCF
SBC HL,HL
INC HL
;
; HL <= B B is zero - true if HL==0
BOOL HL
;
; HL==B and B is a constant
LD DE,(65536-B)
ADD HL,DE
BOOL HL
INC HL
RES 1,l
; HL==B and B==0
BOOL HL
INC HL
RES 1,l
and B is zero
B is constant not zero
; carry set if HL>B
; HL-HL-C
; 14 total clocks - true if HL>B
; 14 clocks
; 6 clocks
; not carry if HL<B
; -1 if carry, else 0
; 14 clocks --0 if carry, else 1 if no carry
; ~C if HL<=B
; C if true
; if C -1 else 0
; 16 clocks -- 1 if true, else 0
; result in HL
; zero if equal
; 16 clocks
; 8 clocks
65535-B
B is constant
LD DE,(65535-B)
B
.
, but simply indicates the difference between 65535 and
- result -1 if carry set, else zero
not zero
does not indicate a load of
SBC
. In the following examples, the
DE
with the
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