MVME5100 Single Board Computer Programmer's Reference Guide

Programming Model
each half of the SMC interfaces to 32 bits. rom_a_64
matches the value that was on the RD2 pin at power-up
reset. It cannot be changed by software.
rom a siz The rom a siz control bits are the size of ROM/Flash for
Block A. They are encoded as shown in Table 3-11.
Table 3-11. ROM Block A Size Encoding
rom a siz
BLOCK
SIZE
%000 1MB
%001 2MB
%010 4MB
%011 8MB
%100 16MB
%101 32MB
%110 64MB
%111 Reserved
rom_a_rv rom_a_rv and rom_b_rv determine which if either of
Blocks A and B is the source of reset vectors or any other
access in the range $FFF00000 - $FFFFFFFF as shown in
the table below.
Table 3-12. rom_a_rv and rom_b_rv encoding
rom_a_rv rom_b_rv Result
0 0 Neither Block is the source of
reset vectors.
0 1 Block B is the source of reset
vectors.
1 0 Block A is the source of reset
vectors.
1 1 Block B is the source of reset
vectors.
http://www.motorola.com/computer/literature 3-55
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