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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.
Pins | Type | Function |
---|---|---|
A15 – A0 | Output | 16-bit address bus, which provides the addresses for memory (up to 64KB) |
D7 – D0 | Input/Output | 8-bit bi-directional data bus to transfer data between memory/IO devices and CPU. |
BUSACK | Output | It is Bus Acknowledge pin. It indicates the requesting device that the address bus, data bus, control bus enter into a high impedance state. |
BUSREQ | Input | 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. |
HALT | Output | The Halt state indicates the CPU has executed a HALT instruction and waiting for interrupt. |
INT | Input | Interrupt Request pin is used to generate interrupts by IO devices. After executing each instruction, CPU checks for the Interrupt requests |
IORQ | Output | The Input Output request pin is used to return low (0) signal when communication with IO ports is desired. |
M1 | Output | It indicates the Machine Cycle number 1. So the CPU activates this output, when the first machine cycle of an instruction is in progress. |
MREQ | Output | The memory request pin used to return low (0) signal, when communication with memory blocks is desired. |
RD | Output | It indicates that the CPU wants to read the data from memory or IO devices. |
WR | Output | It indicates the data bus contains to be stored at the addressed memory or IO locations. |
NMI | Input | 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. |
RESET | Input | 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. |
RFSH | Output | 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. |
WAIT | Input | 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. |
CLK | Input | Single phase MOS level Clock |
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