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Only SRAM chips with center power pins can be used. See the Appendix for

details.

Address latch

The data bus and the low byte of the address bus is multiplexed on PORTA. The

ALE signal indicates when the address is present. This low byte must be stored

by a latch until the memory access cycle is completed.

The STK503's a latch is connected to the ALE signal. The latched low byte of the

address is routed to the SRAM footprint, and is also accessible on the connector

marked A[7:0].

High address jumpers

Some or all of the highest eight address pins on the External Memory Interface

can be disabled and used as general I/O. This feature is supported on STK503

by mounting the appropriate RAM HIGH ADDRESS jumpers. The lines which are

disconnected from the SRAM footprint are pulled low so the address lines of the

SRAM isn't floating.