Z86C34 Datasheet, PDF (29/70 Pages) Zilog, Inc. – CMOS Z8 MCUs WITH ASCI UART OFFER EFFICIENT, COST-EFFECTIVE DESIGN FLEXIBILITY

ZiLOG
Z86C34/C35/C36/C44/C45/C46
CMOS Z8® MCUs with ASCI UART
FUNCTIONAL DESCRIPTION
The Z8 MCU incorporates the following special functions
to enhance the standard Z8^® architecture to provide the user
with increased design flexibility.
RESET. The device is reset in one of the following condi-
tions:
• Power-On Reset
• Watch-Dog Timer
• Stop-Mode Recovery Source
• External Reset
• Low Voltage Recovery
Auto Power-On Reset circuitry is built into the Z8, elimi-
nating the requirement for an external reset circuit to reset
upon power-up. The internal pull-up resistor is on the Reset
pin, so a pull-up resistor is not required; however, in a high-
EMI (noisy) environment, it is recommended that a small
value pull-up resistor be used.
Note: The RESET pin is not available on devices in the 28-pin
package.
Program Memory. The first 12 bytes of program memory
are reserved for the interrupt vectors. These locations con-
tain six 16-bit vectors that correspond to the six available
interrupts. For ROM mode, address 12 to address 65535
(C36/C46)/32767 (C35/C45)/16383 (C34/C44) consists
of on-chip mask-programmed ROM. The Z86C44/C45 can
access external program and data memory from addresses
16384/32768 to 65535.
The 65535 (C36/C46)/32767 (C35/C45)/16383
(C34/C44) program memory is mask programmable. A
ROM protect feature prevents dumping of the ROM con-
tents by inhibiting execution of LDC, LDCI, LDE, and LDEI
instructions to Program Memory in external program
mode. ROM look-up tables can be used with this feature.
The ROM Protect option is mask-programmable, to be se-
lected by the customer when the ROM code is submitted.
65535
16383/32767
16382/32766
Location of
First Byte of
Instruction
Executed
After RESET 12
11
10
9
8
7
Interrupt
Vector ₆
(Lower Byte)
5
4
Interrupt
Vector ₃
(Upper Byte)
2
1
0
External/Internal
ROM and RAM
On-Chip
ROM
IRQ5
IRQ5
IRQ4
IRQ4
IRQ3
IRQ3
IRQ2
IRQ2
IRQ1
IRQ1
IRQ0
IRQ0
Figure 17. Program Memory Map
for Z86C34/35/44/45
Data Memory (DM). The ROMless version can address up
to 64 KB of external data memory. External data memory
may be included with, or separated from, the external pro-
gram memory space. DM, an optional I/O function that can
be programmed to appear on pin P34, is used to distinguish
between data and program memory space (Figure 18). The
state of the DM signal is controlled by the type of instruction
being executed. An LDC Op Code references PROGRAM
(DM inactive) memory, and an LDE instruction references
data (DM active Low) memory. The user must configure
Port 3 Mode Register (P3M) bits D3 and D4 for this mode.
This feature is not usable for devices in 28-pin package.
When used in ROM mode, the Z86C46 cannot access any
external data memory. The Z86C44/C45 can access exter-
DS007601-Z8X0499
PRELIMINARY
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