Z86C61 Datasheet, PDF (18/46 Pages) Zilog, Inc. – CMOS Z8 MICROCONTROLLER

PIN FUNCTIONS (Continued)
Z86C61/62/96
Z8^® MICROCONTROLLER
Port 4 (P47-P40). Port 4 is an 8-bit, bit programmable,
bidirectional, CMOS compatible port. Each of these eight
I/O lines can be independently programmed as an input or
output or globally as an open-drain output. Port 4 is always
available for I/O operation (Figure 15). Port address (F)02.
Port 5 (P57-P50). Same as Port 4. Port address (F)04.
Port 6 (P63-P60). Same as Port 4. (Note: this is a 4-bit port,
bits D3-D0.) Port address (F)07.
Auto Latch. The Auto Latch puts valid CMOS levels on all
CMOS inputs that are not externally driven. This reduces
excessive supply current flow in the input buffer when it is
not being driven by any source.
MCU
Port 4 (I/O)
Open-Drain
OEN
PAD
Out
TTL Level Shifter
In
R ≈ 500 KΩ
Figure 15. Port 4 Configuration
Auto Latch
18