z86c9216vsc ZiLOG Semiconductor, z86c9216vsc Datasheet - Page 31

• Manufacturer Part Number: z86c9216vsc
• Description: Ir Microcontroller
• Manufacturer: ZiLOG Semiconductor

Zilog
External Memory (/DM). The Z86L72 addresses up to
48K bytes (minus Extended Data RAM space) of external
memory beginning at address 16384 (Figure 18). External
data memory is included with, or separated from, the ex-
ternal program memory space. /DM, an optional I/O func-
tion that is programmed to appear on P34, is used to dis-
tinguish between data and program memory space. The
state of the /DM signal is controlled by the type of instruc-
tion being executed. An LDC opcode references PRO-
GRAM (/DM inactive) memory, and an LDE instruction ref-
erences data (/DM active Low) memory.
DS97LVO0900
16,384
65535
0
Figure 18. Data Memory Map
Not Addressable
External
Memory
Data
Z86L72
and
Z86E72
versions
P R E L I M I N A R Y
Expanded Register File. The register file has been ex-
panded to allow for additional system control registers,
and for mapping of additional peripheral devices into the
register address area. The Z8 register address space R0
through R15 has been implemented as 16 groups of 16
registers per group. These register groups are known as
the ERF (Expanded Register File). Bits 7-4 of register RP
select the working register group. Bits 3-0 of register RP
select the expanded register file bank. Note that expanded
register bank is also referred to as expanded register
group (Figure 19).
The upper nibble of the register pointer (Figure 21) selects
which working register group of 16 bytes in the register file,
out of the possible 256, will be accessed. The lower nibble
selects the expanded register file bank and, in the case of
the Z86L/CX2 family, banks 0, F, and D are implemented.
A 0H in the lower nibble will allow the normal register file
(bank 0) to be addressed, but any other value from 1H to
FH will exchange the lower 16 registers to an expanded
register bank (See Figure 19).
For example:
R253 RP = 00H
But if:
R253 RP = 0DH
The counter/timers are mapped into ERF group D. Access
is easily done using the following example:
LD
LD
LD
LD
LD
LD
LD
R0 = Port 0
R1 = Port 1
R2 = Port 2
R3 = Port 3
R0 = CTRL0
R1 = CTRL1
R2 = CTRL2
R3 = Reserved
RP, #0DH Select ERF D for access to bank D( work-
ing register group 0)
R0,#xx
R1, #xx
R1, 2
RP, #7DH Select expanded register bank D and
working register group 7 of bank 0 for access .
71H, R2
R1, R2
Load CTRL0
Load CTRL1
CTRL2
CTRL2
CTRL2
CTRL1
register 71H
register 71H
Z86C72/C92/L72/L92
IR Microcontroller
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