Table 3-11. Rom Block A Size Encoding - Motorola MVME2400 Series Programmer's Reference Manual

System Memory Controller (SMC)
3
3-54
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
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 the following table.

Table 3-11. ROM Block A Size Encoding

rom a siz
%000
%001
%010
%011
%100
%101
%110
%111
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
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.
rom_a_rv is initialized at power-up reset to match the value on the
RD0 pin.
BLOCK
SIZE
1MB
2MB
4MB
8MB
16MB
32MB
64MB
Reserved
Result
Computer Group Literature Center Web Site