1. Introduction
ÛZIATECH
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Serial I/O
The ZT 8907 includes two PC-compatible serial ports. The serial ports are implemented
with a 5 V charge pump technology to eliminate the need for a ±12 V supply. Both serial
ports include a complete set of handshaking and modem control signals, maskable
interrupt generation, and data transfer rates up to 115.2 Kbaud.
The serial ports are configured as DTE and are available through 10-pin frontplane
connectors (J3 COM2 and J4 COM1). Optional cables interface the frontplane
connectors to standard 9-pin D-shell connectors (male). For more on the operation of
the two serial ports, see Chapter 8, "
Parallel I/O
The ZT 8907 includes three 8-bit parallel I/O ports for a total of 24 parallel I/O lines.
Each line is programmable as an input or an output with readback. All three ports
include event sense capability where a positive or negative transition on the input will
generate an onboard interrupt.
All inputs also feature a programmable debounce circuit. The outputs sink 12 mA and
do not glitch during power up or power down. The 24 lines are available through a 50-
pin frontplane connector (J5). Optional cables interface the frontplane connector to
an 8-, 16-, or 24-position I/O module mounting rack, such as Ziatech's ZT 2226 24-
Channel I/O Mounting Rack or those offered by Opto 22. See Chapter 10, "
for more information.
Interrupts
The ZT 8907's two interrupt controllers provide a total of 15 interrupt inputs. Interrupt
controller features include support for level-triggered and edge-triggered inputs, fixed
and rotating priorities, and individual input masking.
Interrupt sources include counter/timers, serial I/O, real-time clock, keyboard, printer,
hard disk, floppy disk and multiple master communications. There are also five
frontplane and five backplane interrupt sources. See Chapter 4, "
for more information.
Counter/Timers
Six counter/timers are included on the ZT 8907. Operating modes supported by the
counter/timers include interrupt on count, frequency divider, square wave generator,
software triggered, hardware triggered, and one shot.
Three of the counter/timers are dedicated to supporting local devices. Three additional
counter/timers are available through a 10-pin frontplane connector (J2). See Chapter 5,
"
," for more information.
