Z80180 Datasheet, PDF (26/326 Pages) Zilog, Inc. – Z8018x Family MPU

Z 8018x Fam ily
M PU Us e r M anual
11
TOUT. Timer Out (Output, Active High). TOUT is the pulse output from
PRT channel 1. This line is multiplexed with A18 of the address bus.
TXA0, TXA1. Transmit Data 0 and 1 (Outputs, Active High). These
signals are the transmitted data from the ASCI channels. Transmitted data
changes are with respect to the falling edge of the transmit clock.
TXS. Clocked Serial Transmit Data (Output, Active High). This line is
the transmitted data from the CSIO channel.
WAIT. Wait (Input; Active Low). WAIT indicates to the CPU that the
addressed memory or I/O devices are not ready for a data transfer. This
input is used to induce additional clock cycles into the current machine
cycle. The WAIT input is sampled on the falling edge of T2 (and
subsequent Wait States). If the input is sampled Low, then additional
Wait States are inserted until the WAIT input is sampled High, at which
time execution continues.
WR. Write (Output, Active Low, 3-state). WR indicates that the CPU data
bus holds valid data to be stored at the addressed I/O or memory location.
XTAL. Crystal (Input, Active High). Crystal oscillator connection. This
pin must be left open if an external clock is used instead of a crystal. The
oscillator input is not a TTL level (reference DC characteristics).
Multiplexed pins are described in Table 2.
UM005001-ZMP0400