Z89135 Datasheet, PDF (27/66 Pages) Zilog, Inc. – Low-Cost DTAD Controller

Zilog
Z89135/136 (ROMless)
Low-Cost DTAD Controller
Port 5. (P57-P50). Port 5 is an 8-bit, bidirectional, CMOS- Port 5 is a bit programmable general-purpose I/O port. The
compatible I/O port (Figure 15). These eight I/O lines are control registers for Port 5 are mapped into the expanded
configured under software control as an input or output, in- register file (Bank F) of the Z8.
dependently. Port 5 is always available for I/O operation.
1
The input buffers are Schmitt-triggered. Bits programmed ^{Auto Latch. The Auto Latch on Port 5 puts valid CMOS}
as outputs may be globally programmed as either push- ^{levels on all CMOS inputs which are not externally driven.}
pull or open-drain.
Whether this level is 0 or 1, cannot be determined. A valid
CMOS level, rather than a floating node, reduces exces-
sive supply current flow in the input buffer.
Z89135/136
MCU
Port 5
(I/O)
Open-Drain
OEN
Out
1.5
2.3V Hysteresis
In
R = 500 KΩ
Figure 15. Port 5 Configuration
PAD
Auto Latch
DS97TAD0300
PRELIMINARY
1-27