Z86E61 Datasheet, PDF (10/44 Pages) Zilog, Inc. – CMOS Z8 16K/32K EPROM MICROCONTROLLER

PIN FUNCTIONS (Continued)
PRELIMINARY
Z86E61/E63 Z8^® MCU
WITH 16K/32K EPROM
Port 2 (P27-P20). Port 2 is an 8-bit, bit programmable, bi-
directional, 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 2 is always
available for I/O operation. When used as an I/O port,
Port 2 can be placed under handshake control. In this
configuration, Port 3 lines P31 and P36 are used as the
handshake control lines /DAV2 and RDY2. The handshake
signal assignment for Port 3 lines, P31 and P36, is dictated
by the direction (input or output) assigned to P27
(Figure 8 and Table 5).
Z86E61
/E63
MCU
Open-Drain
OEN
Port 2 (I/O)
Handshake Controls
/DAV2 and RDY2
(P31 and P36)
PAD
Out
TTL Level Shifter
In
R ≈ 500 kΩ
Auto Latch
Figure 8. Port 2 Configuration
10