Z86C34 Datasheet, PDF (22/70 Pages) Zilog, Inc. – CMOS Z8 MCUs WITH ASCI UART OFFER EFFICIENT, COST-EFFECTIVE DESIGN FLEXIBILITY

Z86C34/C35/C36/C44/C45/C46
CMOS Z8® MCUs with ASCI UART
ZiLOG
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 V_CC, 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 V_CC.
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.)
22
PRELIMINARY
DS007601-Z8X0499