Artesyn MVME5100, Programmer'S Reference Manual, Page: 248 / 318

System Memory Controller (SMC)
MVME5100 Single Board Computer Programmer’s Reference (6806800H17B )
248
rom_a_64 indicates the width of ROM/Flash being used for Block A. When rom_a_64 is
cleared, Block A is 16 bits wide, where each half of SMC interfaces to 8 bits. When rom_a_64 is
set, Block A is 64 bits wide, where 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 2-221.
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 3-25 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
Table 3-26 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.