CHAPTER 4: INSTRUCTION SET

JRNC sign8

Jump to relative location sign8 if C flag is reset

1 cycle

Function: If C = 0 then PC ← PC + sign8 + 1 (sign8 = -128~127)

Executes the "JR sign8" instruction if the C (carry) flag has been reset to "0", otherwise executes the next instruction.

Code:

Mnemonic

 

MSB

 

 

 

 

 

LSB

 

JRNC sign8

 

 

0

0

1

0

1

s7

s6

s5

s4

s3

s2

s1

s0

0500H–05FFH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flags:

E

I

C

 

Z

 

 

 

 

 

 

 

 

 

 

↓

–

–

 

–

 

 

 

 

 

 

 

 

 

Mode:

Signed 8-bit PC relative

 

 

 

 

 

 

 

 

 

Extended addressing: Valid

 

 

 

 

 

 

 

 

Extended

LDB

%EXT,imm8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

operation: JRNC sign8

 

 

If C = 0 then PC ←

PC + sign16 + 1

 

 

 

(sign16 = -32768 to 32767, upper 8-bit: imm8, lower 8-bit: sign8)

JRNZ sign8

Jump to relative location sign8 if Z flag is reset

1 cycle

Function: If Z = 0 then PC ← PC + sign8 + 1 (sign8 = -128~127)

Executes the "JR sign8" instruction if the Z (zero) flag has been set to "1", otherwise executes the next instruction.

Code:

Mnemonic

 

MSB

 

 

 

 

 

LSB

 

JRNZ sign8

 

 

0

0

1

1

1

s7

s6

s5

s4

s3

s2

s1

s0

0700H–07FFH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flags:

E

I

C

 

Z

 

 

 

 

 

 

 

 

 

 

 

 

 

↓

–

–

 

–

 

 

 

 

 

 

 

 

 

 

 

 

Mode:

Signed 8-bit PC relative

 

 

 

 

 

 

 

 

 

Extended addressing: Valid

 

 

 

 

 

 

 

 

Extended

LDB

%EXT,imm8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

operation: JRNZ sign8

 

 

If Z = 0 then PC ←

PC + sign16 + 1

(sign16 = -32768 to 32767, upper 8-bit: imm8, lower 8-bit: sign8)

98

EPSON

S1C63000 CORE CPU MANUAL