Pins of Z-80

The Zilog Z-80 is 40 pin DIP Microprocessor. Here we will see the actual pin level diagram of Z-80 and also the functional pin diagram of it.

This is the actual pin diagram of Z-80 Microprocessor. Now we will see the functional pin diagram of it.

Now let us see the Pin functions of the Z-80 microprocessor.

A15 – A0
16-bit address bus, which provides the addresses for memory (up to 64KB)
D7 – D0
8-bit bi-directional data bus to transfer data between memory/IO devices and CPU.
It is Bus Acknowledge pin. It indicates the requesting device that the address bus, data bus, control bus enter into a high impedance state.
Bus request Pin forces the address bus, data bus and control bus to enter a high impedance state. It is always recognized at the end of each machine cycle.
The Halt state indicates the CPU has executed a HALT instruction and waiting for interrupt.
INTInputInterrupt Request pin is used to generate interrupts by IO devices. After executing each instruction, CPU checks for the Interrupt requests
The Input Output request pin is used to return low (0) signal when communication with IO ports is desired.
It indicates the Machine Cycle number 1. So the CPU activates this output, when the first machine cycle of an instruction is in progress.
The memory request pin used to return low (0) signal, when communication with memory blocks is desired.
It indicates that the CPU wants to read the data from memory or IO devices.
It indicates the data bus contains to be stored at the addressed memory or IO locations.
The Non-Maskable Interrupt pin is negative edge triggered. Its priority is higher than the INT. It does not depend on the status of the interrupt enable flip-flops. It automatically forces the CPU to restart at location 0066H.
It resets the current interrupt enabled flip-flops, clears the Program Counter (PC), and the I and R registers. Address and data bus to a high impedance state.
The RFSH and MREQ both can be used to indicate the lower seven bits of the address bus can be used as refresh address for Dynamic memories.
This signal is used for the communication between CPU and memory units or IO devices. Until the signal is inactive the CPU continuously enters the Wait state.
Single phase MOS level Clock