Hardware Reference
In-Depth Information
pc
*
RegisterName
+
*
RegisterValue
+
The
pc
command allows one to change the value of any CPU register (PC, SP, X, Y, A, B, D,
CCR). Each of the fields in the CCR may be modified by using the bit names shown in Table 3.4.
CCR Bit Name
Description
Legal Values
S
H
N
Z
V
C
IM
XM
STOP enable
Half carry
Negative flag
Zero flag
Two's complement overflow flag
Carry flag
IRQ interrupt mask
XIRQ interrupt mask
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
Table 3.4
■
Condition code register bits
Example 3.8
▼
+
pc 2000
PC
SP
X
Y
D
5
A:B
CCR
5
SXHI
NZVC
2000
0A00
0100
0000
00:FF
1101
0001
+
x 800
PC
SP
X
Y
D
5
A:B
CCR
5
SXHI
NZVC
2000
0A00
0800
0000
00:FF
1101
0001
+
c 0
PC
SP
X
Y
D
5
A:B
CCR
5
SXHI
NZVC
2000
0A00
0800
0000
00:FF
1101
0000
+
z 1
PC
SP
X
Y
D
5
A:B
CCR
5
SXHI
NZVC
2000
0A00
0800
0000
00:FF
1101
0100
+
d 2010
PC
SP
X
Y
D
5
A:B
CCR
5
SXHI
NZVC
2000
0A00
0800
0000
20:10
1101
0100
.
▲
asm
*
Address
+
The
asm
command invokes the one-line assembler/disassembler. It allows memory con-
tents to be viewed and altered using assembly-language mnemonics. Each entered source line
is translated into object code and placed into memory at the time of entry. When displaying
memory contents, each instruction is disassembled into its source mnemonic form and dis-
played along with the hex object code and any instruction operands.
Assembly mnemonics and operands may be entered in any mix of upper- and lowercase
letters. Any number of spaces may appear between the assembler prompt and the instruction
mnemonic or between the instruction mnemonic and the operand. Numeric values appearing
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