1. AGENDA Architecture Microprocessor Communication and Bus Timings
Demultiplexing Address and Data Lines

2. Architecture of 8085 Reveals the internal logic of a Microprocessor
8085 Architecture consists of following blocks:
ALU logic
Register Logic
Timing and Execution Logic
Interrupt Logic
Serial I/O Logic

3. Architecture of 8085

4. General Purpose Registers
Register Section
General Purpose Registers
A, B, C, D, E, H, and L
BC, DE, and HL
Special Function Registers
Program Counter
Stack Pointer

5. Flag Register S Z P C X Sign Carry Zero Parity Auxiliary CarryAC P C
Sign
Carry
Zero
Parity
Auxiliary Carry
X - Unspecified

6. Timing and Control Unit
Timing and Execution Logic
Instruction Register
Instruction Decoder
Timing and Control Unit
Control Signals

7. Timing and Execution Logic
Control Signals
READY, RD’,WR’,ALE
Status Signals
S0, S1, IO/M’
DMA Signals
HOLD, HLDA
RESET Signals
RESET IN, RESET OUT

8. Consists of 5 interrupts with following properties:
Interrupt Logic
Consists of 5 interrupts with following properties:
Priority
Maskable and Non Maskable
Vectored and Non – Vectored
INTA is an output signal

9. Serial I/O Logic Supports serial I/O using 2 lines
SID – Serial Input Data
SOD – Serial Output Data

10. Mp communication and Bus Timings
The instruction code (4FH – MOV C, A) is stored in memory location 2005H. Illustrate the steps and the timing of data flow when it is being fetched

11. Mp Communication And Bus Timings
Data Bus 4F
Internal Data Bus
Memory
2000
B C
Instruction Decoder
D E
ALU
H L
2005 4F
2005 SP PC
Control Logic
Address Bus 4F RD

12. Demultiplexing Address & Data Lines

13. What we studied in this session..
8085 Architecture
8085 Communication and bus timings
Demultiplexing Address & Data Lnes

14. Probable Questions..
Explain with a neat diagram, the architecture of 8085 microprocessor
Explain the flag register of 8085.
With a neat diagram, explain how to separate multiplexed address and data lines in 8085.
What Signals are activated when I/O port at address ABCD H is read by 8085 ?

15. Thank You
Q & A