There are two memory blocks in the PIC16F84A.These are the program memory and the data memory.Each block has its own bus, so that access to each block can occur during the same oscillator cycle.The data memory can further be broken down into the general purpose RAM and the Special Function Registers (SFRs).

1.High Performance RISC CPU Features:
? Only 35 single word instructions to learn
? All instructions single-cycle except for program
branches which are two-cycle
? Operating speed: DC - 20 MHz clock input
DC - 200 ns instruction cycle
? 1024 words of program memory
? 68 bytes of Data RAM
? 64 bytes of Data EEPROM
? 14-bit wide instruction words
? 8-bit wide data bytes
? 15 Special Function Hardware registers
? Eight-level deep hardware stack
? Direct, indirect and relative addressing modes
? Four interrupt sources:
- External RB0/INT pin
- TMR0 timer overflow
- PORTB<7:4>interrupt-on-change
- Data EEPROM write complete

2.Peripheral Features:
? 13 I/O pins with individual direction control
? High current sink/source for direct LED drive
- 25 mA sink max. per pin
- 25 mA source max. per pin
? TMR0: 8-bit timer/counter with 8-bit
programmable prescaler

3.Special Microcontroller Features:
? 10,000 erase/write cycles Enhanced FLASH
Program memory typical
? 10,000,000 typical erase/write cycles EEPROM
Data memory typical
? EEPROM Data Retention > 40 years
? In-Circuit Serial Programming? (ICSP?) - via
two pins
? Power-on Reset (POR), Power-up Timer (PWRT),
Oscillator Start-up Timer (OST)
? Watchdog Timer (WDT) with its own On-Chip RC
Oscillator for reliable operation
? Code protection
? Power saving SLEEP mode
? Selectable oscillator options
4.CMOS Enhanced FLASH/EEPROM Technology:
? Low power, high speed technology
? Fully static design
? Wide operating voltage range:
- Commercial: 2.0V to 5.5V
- Industrial: 2.0V to 5.5V
? Low power consumption:
- < 2 mA typical @ 5V, 4 MHz
- 15 μA typical @ 2V, 32 kHz
- < 0.5 μA typical standby current @ 2V