AT89C51RB2_14 Datasheet, PDF (12/127 Pages) ATMEL Corporation – Variable Length MOVX for Slow RAM/Peripherals

Table 12. Pin Description for 40 - 44 Pin Packages (Continued)
Pin Number
Mnemonic
DIL
LCC VQFP44 1.4 Type Name and Function
PSEN
29
32
26
O Program Strobe Enable: The read strobe to external program memory. When
executing code from the external program memory, PSEN is activated twice each
machine cycle, except that two PSEN activations are skipped during each access to
external data memory. PSEN is not activated during fetches from internal program
memory.
EA
31
35
29
I
External Access Enable: EA must be externally held low to enable the device to
fetch code from external program memory locations 0000H to FFFFH (RD). If
security level 1 is programmed, EA will be internally latched on Reset.
12 AT89C51RB2/RC2
4180E–8051–10/06