Epson S1C63000 Manuel D’Utilisation

The following six instructions, which handle the X or Y register and have an 8-bit immediate data as
the operand, permit the extended addressing.

LDB

%XL,imm8

LDB

%YL,imm8

ADD

%X,sign8

ADD

%Y,sign8

CMP

%X,imm8

CMP

%Y,imm8

When data is written to the EXT register and the E flag is set immediately before these instructions,
the data is processed after extending into 16-bit; imm8 (sign8) is used as the low-order 8 bits and the
content of the EXT register is used as the high-order 8 bits.

Examples:

LDB

%EXT,0x15

LDB

%XL,0x7D

...Works as "LD  %X,0x157D"

LDB

%EXT,0xB8

ADD

%X,0x4F

...Works as "ADD  %X, 0xB84F"

LDB

%EXT,0xE6

CMP

%X,0xA2

...Works as "CMP  %X, 0x19A2"
   

∗

 19H = FFH - [EXT] (E6H)

Above examples use the X register, but work the same even when the Y register is used.

Note: The CMP instruction performs a subtraction with a complement, therefore it is necessary to set the

complement (1's complement) of the high-order 8-bit data in the EXT register.
EXT register 

←

 [FFH - High-order 8-bit data]

The following PC relative branch instructions, which have a signed 8-bit relative address as the
operand, permit extended addressing.

JR

sign8

JRC

sign8

JRNC sign8

JRZ

sign8

JRNZ sign8

CALR sign8

When data is written to the EXT register and the E flag is set immediately before these instructions,
the relative address is processed after extending into signed 16-bit; sign8 is used as the low-order 8
bits and the content of the EXT register is as the high-order 8 bits.

Examples:

LDB

%EXT,0x64

JR

0x29

...Works as "JR  0x6429"

LDB

%EXT,0x00

JR

127

...Works as "JR  127"

LDB

%EXT,0xFF

JR

-128

...Works as "JR  -128"

LDB

%EXT,0x3A

JR

∗

0x88

...Works as "JR

∗

  0x3A88" (

∗

 = C, NC, Z, or NZ)

LDB

%EXT,0xF8

CALR 0x62

...Works as "CALR  0xF862"

See Section 2.2.3, "Branch instructions" for the branch instructions.