z86d73 ZiLOG Semiconductor, z86d73 Datasheet - Page 36

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

PS019402-1103
The upper nibble of the register pointer (see Figure 17) selects which working reg-
ister group, of 16 bytes in the register file, is accessed out of the possible 256. The
lower nibble selects the expanded register file bank and, in the case of the
Z86D73 family, banks 0, F, and D are implemented. A
the normal register file (bank 0) to be addressed. Any other value from
exchanges the lower 16 registers to an expanded register bank.
Figure 17. Register Pointer
Example: Z86D73: (See Figure 16 on page 29)
R253 RP = 00h
But if:
R253 RP = 0Dh
The counter/timers are mapped into ERF group D. Access is easily performed
using the following:
R253 RP
D7
Default Setting After Reset = 0000 0000
LD
LD
LD
LD
R0 = Port 0
R1 = Port 1
R2 = Port 2
R3 = Port 3
R0 = CTRL0
R1 = CTRL1
R2 = CTRL2
R3 = Reserved
D6
D5
RP, #0Dh
R0,#xx
1, #xx
R1, 2
D4
P
D3
R
E
D2
; Select ERF D for access to bank D
; (working register group 0)
; load CTRL0
; load CTRL1
; CTRL2→CTRL1
L
D1
I
M
D0
I
N
A
40/44/48-Pin Low-Voltage IR OTP
Expanded Register
File Pointer
Working Register
Pointer
R
Y
0h
in the lower nibble allows
1h
Z86D73
to
Fh
30