Z86C9620VSC datasheet(14/46 Pages) ZILOG

14 / 46 page

Z86C61/62/96

Z8® MICROCONTROLLER

PIN FUNCTIONS (Continued)

Port 1 (P17-P10). Port 1 is an 8-bit, byte programmable,

bidirectional, TTL compatible port. It has multiplexed Ad-

dress (A7-A0) and Data (D7-D0) ports. For Z86C61/62/96,

these eight I/O lines can be programmed as Input or

Output lines or can be configured under software control

as an address/data port for interfacing external memory.

When used as an I/O port, Port 1 may be placed under

handshake control. In this configuration, Port 3 line P33

and P34 are used as the handshake controls RDY1 and

/DAV1.

Memory locations greater than 16,384 are referenced

through Port 1. To interface external memory, Port 1 must

be programmed for the multiplexed Address/Data mode.

If more than 256 external locations are required, Port 0

must output the additional lines.

Port 1 can be placed in high-impedance state along with

Port 0, /AS, /DS, and R//W, allowing the microcontroller to

share common resources in multiprocessor and DMA

applications. Data transfers can be controlled by assign-

ing P33 as a Bus Acknowledge input, and P34 as a Bus

request output (Figure 11).

OEN

Out

PAD

Port 1

(AD7-AD0)

MCU

TTL Level Shifter

Auto Latch

≈ 500 KΩ

Handshake Controls

/DAV1 and RDY1

(P33 and P34)

Figure 11. Port 1 Configuration

Z86C9620VSC Datasheet(PDF) 14 Page - Zilog, Inc.