2. Microprocessor 8085
Architecture of 8085
Pin diagram of 8085
System Bus
Applications of 8085
Disadvantage of 8085
Conclusion
Reference
3.
4. The key element of all computers, providing the
mathematical and decision making ability
They operate at ultra-fast speeds – doing over a
billion operations very second
Made up from a semiconductor, Silicon
6. Year 1977
Enhancement of 8080
40 Pins DIP Package
The 8085 uses approximately
6,500 transistors
Clock Speed: Max 6 MHz
8-bit Data Bus & 16 Bit
Address Bus
7. It is an 8 bit processor.
It is a single chip N-MOS(N Type Metal Oxide
Semiconductor) device with 40 pins DIP
Package.
It uses all instructions of 808 therefore it is
program compatible with 8080
It has multiplexed address and data bus.(AD0-
AD7)
It works on single 5 Volt dc power supply.
8. The maximum clock frequency is 6 MHz while
minimum frequency is 500kHz.
It provides 74 instructions with 5 different
addressing modes, Two new instruction has been
added in 8085, for taking advantage of added
hardware
It provides 16 address lines so it can access 2^16
=64K bytes of memory.
It generates 8 bit I/O address so it can access
2^8=256 input ports.
9. It provides 5 hardware interrupts : TRAP, RST 5.5,
RST 6.5, RST 7.5,INTR.
It provides Acc ,one flag register ,6 general purpose
registers and two special purpose registers(SP,PC).
It provides serial lines SID ,SOD . So serial
peripherals can be interfaced with 8085 directly.
10.
11.
12. ALU
Timing and Control
Unit
General Purpose
Registers
Program Status word
Program Counter
Stack Pointer
Instruction Register
and Decoder
Interrupt Control
Serial I/O Control
Address Bus
Data Bus
13. Arithmetic Logic Unit (ALU)
8085 has 8-bit ALU
Performs arithmetic & Logic operations on data
Timing & Control Unit
Generates timing and control signals
General Purpose Registers
8-bit registers (B,C,D,E,H,L)
16-bit register pairs (BC, DE, HL,PSW)
14. Program Status Word (PSW)
Accumulator and Flag Register can be combined
as a register pair called PSW
Instruction Register and Decoder
Instruction fetched from memory is stored in
Instruction register (8-bit register)
Decoder decodes the instruction and directs the
Timing & Control Unit accordingly
15. Interrupt Control
8085 has 5 interrupt signals
INTR – general purpose interrupt
RST 5.5
RST 6.5 Restart Interrupts
RST 7.5
TRAP – non-mask able interrupt
The interrupts listed above are in increasing order
of priority
16. Serial I/O Control
8085 has two signals for serial communication
SID – Serial Input Data
SOD – Serial Output Data
17. Address Bus
Used to address memory & I/O devices
8085 has a 16-bit address bus
A15 A14
A13 A12 A11 A10 A9 A8
AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
Lower-order
Address
Higher-order
Address
Data Bus
Used to transfer instructions and data
8085 has a 8-bit data bus
Data Bus
18.
19.
20. X1 & X2 are input lines.
RESET IN is used for reset
the microprocessor.
RESET OUT is used to reset
the peripheral devices and other
ICs on the circuit.
SID (Serial Input Data), it
takes 1 bit input from serial port
of 8085.
SOD (Serial Output Data), it
takes 1 bit from Accumulator to
serial port of 8085.
21. TRAP , RST 7.5 , RST 6.5 ,RST
5.5 ,INTR are interrupt lines.
INTA stands for interrupt
acknowledge.
AD0 – AD7 are bidirectional
pins. These pins serve the dual
purpose of transmitting lower
order address and data byte.
A8- A15 are unidirectional pins.
These pins carry the higher order of
address bus.
ALE is used to enable Address
Latch.
22. S0 and S1 are called Status Pins.
I/OM pin tells whether I/O or
memory operation is being
performed.
RD stands for Read. It is a
control signal used for Read
operation either from memory or
from Input device.
WR stands for Write. It is a
control signal used for Write
operation either into memory or
into output device.
23. READY pin is used to
synchronize slower peripheral
devices with fast microprocessor.
HOLD pin is used to request the
microprocessor for DMA transfer.
HLDA stands for Hold
Acknowledge.
+5V power supply is
connected to VCC.
Ground signal is connected to
VSS.
24.
25. There are a number of possible interconnection
systems
A communication pathway connecting two or more
devices
Single and multiple BUS structures are most
common
Power lines may not be shown
e.g. Control/Address/Data bus (PC)
26. Carries data
Remember that there is no difference between
“data” and “instruction” at this level
Width is a key determinant of performance
8, 16, 32, 64 bit
27. Identify the source or destination of data
e.g. CPU needs to read an instruction (data) from a
given location in memory
Bus width determines maximum memory capacity
of system
e.g. 8080 has 16 bit address bus giving 64k
address space
28. Control and timing information
Memory read/write signal
Interrupt request
Clock signals
29.
30. Instrumentation:- Like printing machine,
digital kiosks, credit card processing, security
systems etc
Entertainment:- Microprocessors are also used
in various gaming consoles, DVD player, etc.
Communication :- like: in digital telephone
sets, telephone exchanges, in television, satellite
communication, etc.
31. It might get over-heated, and the limitation it
imposes on the size of data.
32. Microprocessors are the key element of any
computer. 8085 microprocessor is first famous Intel
microprocessor . Its works on 8 pins. But some
drawbacks with 8085 which overcame by the 8086
microprocessor.