z86d73 ZiLOG Semiconductor, z86d73 Datasheet - Page 37

• Manufacturer Part Number: z86d73
• Description: 40/44/48-pin Low-voltage
• Manufacturer: ZiLOG Semiconductor

PS019402-1103
Register File
Note:
The register file (bank 0) consists of 4 I/O port registers, 237 general-purpose reg-
isters, 16 control and status registers (R0–R3, R4–R239, and R240–R255,
respectively), and two expanded registers groups in Banks D (see Table 10) and
F. Instructions can access registers directly or indirectly through an 8-bit address
field, thereby allowing a short, 4-bit register address to use the Register Pointer
(Figure 18). In the 4-bit mode, the register file is divided into 16 working register
groups, each occupying 16 continuous locations. The Register Pointer addresses
the starting location of the active working register group.
Figure 18. Register Pointer—Detail
LD
LD
LD
LD
Working register group E0–EF can only be accessed through
working registers and indirect addressing modes.
{
{
{
{
{
{
{
{
RP, #0Dh
RP, #7Dh
71h, 2
R1, 2
7F
70
6F
60
5F
50
4F
40
3F
30
2F
20
1F
10
0F
00
* RP = 00: Selects Register Group 0, Working Register 0
The upper nibble of the register file address
provided by the register pointer specifies the
active working-register group.
r
7
P
r
6
Specified Working
Register Group 0
Register Group 1
Register Group
r
R
5
I/O Ports
r
4
E
; Select ERF D for access to bank D
; (working register group 0)
; Select expanded register bank D and working
; register group 7 of bank 0 for access.
; CTRL2→register 71h
; CTRL2→register 71h
r
3
L
r
2
I
r
1
M
r
0
I
R253
N
The lower nibble of the
register file address provided
by the instruction points to
the specified register.
R15 to R0
R15 to R4 *
R3 to R0 *
A
40/44/48-Pin Low-Voltage IR OTP
R
Y
Z86D73
31