5

AT49F001A(N)(T)

3365C–FLASH–9/03

BOOT BLOCK PROGRAMMING LOCKOUT OVERRIDE: The user can override the boot

block programming lockout by taking the RESET pin to 12 volts. By doing this, protected boot

block data can be altered through a chip erase, sector erase or word programming. When the

RESET pin is brought back to TTL levels the boot block programming lockout feature is again

active. This feature is not available on the AT49F001AN(T).

PRODUCT IDENTIFICATION: The product identification mode identifies the device and man-

ufacturer as Atmel. It may be accessed by hardware or software operation. The hardware

operation mode can be used by an external programmer to identify the correct programming

algorithm for the Atmel product.

For details, see Operating Modes (for hardware operation) or Software Product Identification.

The manufacturer and device code is the same for both modes.

DATA POLLING: The AT49F001A(N)(T) features DATA polling to indicate the end of a pro-

gram cycle. During a program cycle an attempted read of the last byte loaded will result in the

complement of the loaded data on I/O7. Once the program cycle has been completed, true

data is valid on all outputs and the next cycle may begin. DATA polling may begin at any time

during the program cycle.

TOGGLE BIT: In addition to DATA polling the AT49F001A(N)(T) provides another method for

determining the end of a program or erase cycle. During a program or erase operation, suc-

cessive attempts to read data from the device will result in I/O6 toggling between one and

zero. Once the program cycle has completed, I/O6 will stop toggling and valid data will be

read. Examining the toggle bit may begin at any time during a program cycle.

HARDWARE DATA PROTECTION: Hardware features protect against inadvertent programs

program function is inhibited. (b) Program inhibit: holding any one of OE low, CE high or WE

high inhibits program cycles. (c) Noise filter: pulses of less than 15 ns (typical) on the WE or

CE inputs will not initiate a program cycle.