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Old 24 July 2014, 02:02   #18
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Join Date: Aug 2001
Location: Connecticut USA
Posts: 561
2x 1MB roms = 2MB ROM space.

$E0000000-$E7FFFFFF rom
$F8000000- $FFFFFFFF rom

CS* (rom) = A(23 downto 20)= "11100" or A(23 downto 20) = "11111"
Two roms are interleaved for 32-bit data bus.
ROMS accept A(21 downto 2) for addressing.
Image for kickstart @$F8000000 will be accessed when A(21:20) = "00".
Pulling pins 42 and 1 down to ground on both IC's will mirror kickstart @ $E0000000 and cause extended rom to vanish, but won't kickstart scan that area for ROMTAGS and make duplicate entries for ROM resources during initialization?
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