5 general-purpose register banks, Toshiba – Toshiba TMP87CP24AF User Manual
Page 11
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TOSHIBA
TMP87CM24A/P24A
1.5
General-purpose Register Banks
General-purpose
registers
are
mapped
into
addresses
0040
h
to
OOBF
h
in
the
data
memory
as
shown
in
Figure 1-4. There are 16 register banks, and each bank contains 8-bit registers W, A, B, C, D, E, H, and L.
Figure 1-5 shows the general-purpose register bank configuration.
w
A
B
C
D
E
H
L
—' bank 15 (00B8 to OOBF
h
)
—I bank 14 (00B0to00B7H)
—' bank 13 (OOABtoOOAFH)
bank
12
(OOAO to
00A?
h
)
— bank
4
(
0060
to
006
?H)
—I banks
(
0058
to
005
FH)
— bank
2
(
0050
to
0057
H)
cl (
0048
to
004
FH)
bankO
(
0040
to
0047
H)
(a) Configuration
Example
Bank 0
W
A
(0041
h
)
(0040
h
)
B
C
(0043
h
)
(0042
h
)
D
E
(0045
h
)
(0044
h
)
H
L
(0047
h
)
(0046
h
)
(b) Address assignments of registers
Figure 1-5. General-purpose Register Banks
In addition to access in 8-bit units,
the registers can also be accessed in 16-bit units as the register pairs
WA,
BC,
DE,
and
HL.
Besides
its
function
as
a
general-purpose
register,
the
register
also
has
the
following
functions:
(1)
A,WA
The
A
register
functions
as
an
8-bit
accumulator
and
WA
the
register
pair
functions
as
a
16-bit
accumulator
(W
is
high
byte
and
A
is
low
byte).
Registers
other
than
A
can
also
be
used
as
accumulators for 8-bit operations.
Examples:
®
add
a
, B
;
Adds B contents to
a
contents and stores the result into
a
.
®
SUB WA, 1234H
; Subtracts
1234
h
from WA contents and stores the result into WA.
®
SUB E, A
; Subtracts A contents from E contents, and stores the result into E.
(2)
HL,DE
The
HL
and
DE
specify
a
memory
address.
The
HL
register
pair
functions
as
data
pointer
(HL)
/index
register (HL + d) /base register (HL + C), and the DE register pair function as a data pointer (DE). The
HL
also
has
an
auto-post-
increment
and
auto-pre-decrement
functions.
This
function
simplifies
multiple digit data processing, software LIFO (last-in first-out) processing, etc.
Example 1 : ®
LD
A, (HL)
LD
A, (HL + 52H)
(3)
LD
A, (HL + C)
LD
A, (HL + )
LD
A, (-HL)
; Loads the memory contents at the address specified by HL into A.
; Loads the memory contents at the address specified by the value
obtained by adding 52
h
to HL contents into A.
; Loads the memory contents at the address specified by the value
obtained by adding the register C contents to HL contents into A.
; Loads the memory contents at the address specified by HL into A.
Then increments HL.
; Decrements HL. Then loads the memory contents at the address
specified by new HL into A.
3
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24-11
2002
-
10-03