Introduction
Zilog’s Z84C90 Serial/Parallel Counter/Timer KIO is a multichannel, multipurpose I/O peripheral device designed to provide the end user with a cost-effective and powerful solution to meet an assortment of peripherals requirements. The Z84C90 KIO Peripheral combines the features of one Z84C30 CTC, one Z84C20 PIO and a Z84C4x SIO, plus an 8-bit, bit-programmable I/O port and a crystal oscillator into a single 84-pin PLCC or 100-pin LQFP package. Utilizing fifteen internal registers for data and programming information, the KIO can easily be configured to any given system environment. Although optimum performance is obtained with a Z84C00 CPU, the KIO can just as easily be used with any other CPU.

FEATUREs
The Z84C90 Serial/Parallel Counter/Timer KIO offers the following features:
• Two independent synchronous/asynchronous serial channels
• Three 8-bit parallel ports
• Four independent counter/timer channels
• On-chip clock oscillator/driver
• Software/hardware resets
• Designed in CMOS for low power operations
• Supports Z80 Family interrupt daisy chain
• Programmable interrupt priorities
• 8, 10 and 12.5 MHz bus clock frequency
• Single +5 V power supply