Zilog Z80 Microprocessor

1. Zilog Z80
An early Z80 microprocessor, manufactured in June 1976

2. Group Members
▪ Md Shalauddin Shanto 201614013
▪ Hasibur Rahman Porag 201614023
▪ Maj Md Mursalin Mahmud 201514003
▪ Tasreef Abdullah Araf 201514051

3. Introduction
▪ It is 8 bit Microprocessor.
▪ Many microprocessor-based systems are designed around the Z80.
▪ Z80 microprocessor needs an external oscillator circuit to provide
the operating frequency.
▪ Also, needs an external oscillator to provide the control signals.

4. Z80 Architechture
It has 16-bit address line and 40 pins.
It has 4 different versions.
• Z80
• Z80A
• Z80B
• Z80H

5. Address Bus
▪ 16 tri-state signal lines ( A15 – A0 )
▪ These lines are unidirectional and capable of addressing 64K (216)
memory registers
▪ The address bus is used to send (or place) the addresses of memory
registers and I/O devices.

6. Data Bus
▪ Consists of eight tri-state bidirectional lines (D7 – D0)
▪ Data can flow in either direction-from the microprocessor to
memory and I/Os or vice versa.

7. Pin Diagram

8. Control and Status Signals
▪ M1- Machine Cycle One
▪ MREQ - Memory Request
▪ IORQ- I/O Request
▪ RD- Read
▪ WR– Write

9. External Request Signals
▪ RESET – Reset
▪ INT– Interrupt Request
▪ NMI– Nonmaskable Interrupt
▪ BUSRQ– Bus Request
▪ WAIT–Wait

10. Special Signals
▪ BUSAK – BusAcknowledge
▪ HALT – Halt
▪ RFSH– Refresh

11. Registers
▪ General Purpose Registers (B,C,D,E,H,L)
▪ Accumulator Register (A)
▪ Flag/Status Register
▪ Alternate Register Set
▪ Index Registers

12. Instruction Cycle
▪ Instruction cycle is defined as the time required completing the
execution of an instruction.
▪ Consists of one to six machine cycles or one to six operations.
OUT (10H),A

13. Machine Cycle

14. Block Diagram

15. Instruction Set
The Z80 CPU can execute 158 different instruction types including all 78 of the
8080A CPU.The instructions fall into these major groups:
▪ Load and Exchange
▪ BlockTransfer and Search
▪ Arithmetic and Logical
▪ Rotate and Shift
▪ Bit Manipulation (Set, Reset,Test)
▪ Jump, Call, and Return
▪ Input/output
▪ Basic CPU Control

16. Evolution
▪ Zilog Z80 may called as an updated version of Intel 8080
▪ It has …..
1 . Extra 120 instruction
2 . More registers
3 . Simplified ConnectionTo hardware

17. Evolution
▪ Z280 (1987) which has a 16MB on board cache, very complex
instruction set and also handles 16MB RAM
▪ Z180 (1986) which handles 1MB RAM and clock speed up to 33MHz
▪ Then came the EZ80, at up to 50MHz. No MMU but 24-bit registers
for 16MB of RAM.
▪ Probably the most logical successor was the ASCII Corp R800 (1990),
an extended 16-bit Z800-based design, mostly Z80 compatible but
double-clocked on a ~8MHz bus for ~16MHz operation.

18. Thanks!!