Z80180 Datasheet, PDF (34/326 Pages) Zilog, Inc. – Z8018x Family MPU

Z 8018x Fam ily
M PU Us e r M anual
19
The Op Code on the data bus is latched at the rising edge of T3 and the
bus cycle terminates at the end of T3.
Phi
A0–A19
D0–D7
T1
T2
T3
T1
T2
WAIT
M1
MREQ
RD
Figure 9. Op Code Fetch (without Wait State) Timing Diagram
Figure 10 illustrates the insertion of Wait States (TW) into the Op Code
fetch cycle. Wait States (TW) are controlled by the external WAIT input
combined with an on-chip programmable Wait State generator.
At the falling edge of T2 the combined WAIT input is sampled. If WAIT
input is asserted Low, a Wait State (TW) is inserted. The address bus,
MREQ, RD and M1 are held stable during Wait States. When WAIT is
sampled inactive High at the falling edge of TW, the bus cycle enters T3
and completes at the end of T3.
UM005001-ZMP0400