Z86C34 datasheet(22/70 Pages) ZILOG

22 / 70 page

Z86C34/C35/C36/C44/C45/C46

CMOS Z8® MCUs with ASCI UART

ZiLOG

P R E L I M I N A R Y

DS007601-Z8X0499

PIN FUNCTIONS

R/RL (input, active Low).

The ROM/ROMless pin, when

connected to GND, disables the internal ROM and forces

the device to function as a ROMless Z8. (Not available for

devices in the 28-pin package.)

Notes: When left unconnected or pulled High to VCC, the

device functions normally as a Z8 ROM version.

When using in ROM Mode in a high-EMI (noisy)

environment, the ROMless pins should be connected

directly to VCC.

DS (output, active Low).

Data Strobe is activated one

time for each external memory transfer. For a READ oper-

ation, data must be available prior to the trailing edge of DS.

For WRITE operations, the falling edge of DS indicates that

output data is valid. (Not available for devices in the 28-

pin package.)

AS (output, active Low).

Address Strobe is pulsed one

time at the beginning of each machine cycle for external

memory transfer. Address output is from Port 0/Port 1 for

all external programs. Memory address transfers are valid

at the trailing edge of AS. Under program control, AS is

placed in the high-impedance state along with Ports 0 and

1, Data Strobe, and READ/WRITE. (Not available for de-

vices in the 28-pin package.)

XTAL1 Crystal 1 (time-based input).

This pin connects a

parallel-resonant crystal, ceramic resonator, LC, or RC net-

work, or an external single-phase clock to the on-chip os-

cillator input.

XTAL2 Crystal 2 (time-based output).

This pin connects

a parallel-resonant crystal, ceramic resonant, LC, or RC net-

work to the on-chip oscillator output.

R/W (output, WRITE Low).

The READ/WRITE signal is

Low when the Z8 is writing to the external program or data

memory. (Not available for devices in the 28-pin package.)

Z86C34 Datasheet(PDF) 22 Page - Zilog, Inc.

Z86C34 Datasheet(HTML) 22 Page - Zilog, Inc.

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