LSI LSI53C896, Technical Manual

Page: 111 / 370

MAD Bus Programming 3-23
•
MAD[3:1] – These pins set the size of the external expansion ROM
device attached. Encoding for these pins is listed in
Table 3.18 (“0”
indicates a pull-down resistor is attached, “1” indicates a pull-up
resistor attached).
•
MAD[0], slow ROM – When pulled up, it enables two extra cycles of
data access time to allow use of slower memory devices.
Note: All MAD pins have internal pull-down resistors.
Table 3.18 Decode of MAD[3:1] Pins
MAD[3:1] Available Memory Space
000 16 Kbytes
001 32 Kbytes
010 64 Kbytes
011 128 Kbytes
100 256 Kbytes
101 512 Kbytes
110 1024 Kbytes
111 no external memory present
*