The document discusses key aspects of the 8051 microcontroller architecture. It describes the 8051's features such as 4KB of program memory, 128 bytes of internal RAM divided into register, bit-addressable and scratchpad RAM, 32 general purpose registers, and ports. It also explains the program status word which contains status flags like carry, auxiliary carry, and overflow to reflect the CPU state. Finally, it provides the pin diagram of the 8051 microcontroller.

1. BIRLA INSTITUTE OF TECHNOLOGY, MESRA
SRINAL
BTECH/25090/20
ECE:304 MICROPROCESSORS AND
MICROCONTROLLERS

2. CONTENT
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 ARCHITECTURE OF 8051
 FEATURES OF 8051
 INTERNAL RAM OF 8051
 PIN DIAGRAM OF 8051
 PROGRAM STATUS WORD

3. ARCHITECTURE OF 8051
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4. FEATURES OF 8051
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 4KB bytes on-chip program memory (ROM)
 128 bytes on-chip data memory (RAM)
 Four register banks
 128 user defined software flags
 8-bit bidirectional data bus
 16-bit unidirectional address bus
 32 general purpose registers each of 8-bit
 Three internal and two external Interrupts
 Four 8-bit ports
 16-bit program counter and data pointer

5. INTERNAL RAM 0F 8051
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Internal RAM of 8051 it is divided into 3 main
sections:-
 REGISTER RAM
 Bit Addressable RAM
 Scratch PAD RAM

6. PROGRAM STATUS WORD
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The PSW register contains several status bits that
reflect the current state of the CPU.
CY PSW.7 Carry flag
AC PSW.6 Auxiliary carry flag
FO PSW.5 Available to the user for general
purpose
RS1 PSW.4 Register bank selector bit
RS0 PSW.3 Register bank selector bit 0
OV PSW.2 Overflow flag
- PSW.1 User definable flag
P PSW.0 Parity flag

7. PIN DIAGRAM OF 8051
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