Device operation M27C512
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2.7 Program Inhibit
Programming of multiple M27C512s in parallel with different data is also easily
accomplished. Except for E
, all like inputs including GV
PP
of the parallel M27C512 may be
common. A TTL low level pulse applied to a M27C512's E
input, with V
PP
at 12.75V, will
program that M27C512. A high level E
input inhibits the other M27C512s from being
programmed.
2.8 Program Verify
A verify (read) should be performed on the programmed bits to determine that they were
correctly programmed. The verify is accomplished with G
at V
IL
. Data should be verified with
t
ELQV
after the falling edge of E.
2.9 Electronic Signature
The Electronic Signature (ES) mode allows the reading out of a binary code from an
EPROM that will identify its manufacturer and type. This mode is intended for use by
programming equipment to automatically match the device to be programmed with its
corresponding programming algorithm. The ES mode is functional in the 25°C ± 5°C
ambient temperature range that is required when programming the M27C512. To activate
the ES mode, the programming equipment must force 11.5V to 12.5V on address line A9 of
the M27C512. Two identifier bytes may then be sequenced from the device outputs by
toggling address line A0 from V
IL
to V
IH
. All other address lines must be held at V
IL
during
Electronic Signature mode. Byte 0 (A0 = V
IL
) represents the manufacturer code and byte 1
(A0 = V
IH
) the device identifier code. For the STMicroelectronics M27C512, these two
identifier bytes are given in <Blue>Table 4. and can be read-out on outputs Q7 to Q0.
