Zilog Z86193 - Manual (Page 20)

Z8
®
CPU
User Manual
UM001604-0108 Address Space
13
The upper nibble of the register pointer selects which group of 16 bytes in the Register
File, out of the 256 total bytes, is accessed as working registers.
Table 5 lists an example.
1001b 9 Expanded Register File Bank 9
1010b A Expanded Register File Bank A
1011b B Expanded Register File Bank B
1100b C Expanded Register File Bank C
1101b D Expanded Register File Bank D
1110b E Expanded Register File Bank E
1111b F Expanded Register File Bank F
* The Z8
®
Standard Register File is equivalent to Expanded Register File
Bank 0.
Table 5. Register Pointer Access Example
R253 RP = 00h ;ERF Bank 0, Working Reg.
Group 0
R0 = Port 0 = 00h
R1 = Port 1 = 01h
R2 = Port 2 = 02h
R3 = Port 3 = 03h
R11 = GPR 0Bh
R15 = GPR 0Fh
If R253 RP = 0Fh ;ERF Bank F, Working Reg.
Group 0
R0 = PCON = 00h
R1 = Reserved = 01h
R2 = Reserved = 02h
R11 = SMR = 0Bh
R15 = WDTMR = 0Fh
Table 4. ERF Bank Address (Continued)
Register Pointer
(FDh) Low Nibble
Hex Register File