AT27C520 EPROM用作AT89XXX系列微控制器的，89xxx

The Atmel AT27C520 EPROM, with its
64K Bytes of storage, combined with a
novel multiplexed address/data scheme
and an internal latch pin, make it the
ideal External Program Memory storage
solution for the Atmel AT89XXX Micro-
Controller family. A simple scheme can
be constructed where the AT89XXX P0
port serves as both the lower order
address byte (to the EPROM) as well as
the data bus (from the EPROM), while
the P2 port serves as the high order
address byte (to the EPROM). Additionally,
the AT27C520 can be accessed in
less than 90 nS. max. eliminating wasteful
wait states. Figure 1 shows the necessary
block diagram. Table 1 contains
the necessary interface connections.