BRIGHT
Microelectronics
Inc.
Preliminary BM29F040
APPENDIX A
Compatibility to AMD's AMD29F040B
The device is fully functional compatible to the AMD29F040B except during the command addresses
subset mode. In the AMD device, Commands do not require a unique address pattern for bits A15,
A14, A13, A12 or A11 (eg.X555H or X2AAH instead of 5555H and 2AAAH). That is, the BM29F040
requires specifically A14,A13,A12 and A11 to be forced during the command sequence in addition to
A10 through A0. Note specifically that the BM29F040 does not require address A15 along with A18,
A17 and A16 to be forced during the command sequence.
AMD's reduced address requirement makes their device slightly easier to inadvertently create a
Command and cause some program error or malfunction. The advantage of reducing the address is
to simplify the hardware interface in systems where control signals are limited in number. The
29F040B reduces the interface requirement by 4 signals -- from 15 to 11 address control pins.
However if the full Command address is supplied (i.e. 2AAAH and 5555H) by the host system, there
will be no incompatibility using either device.
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