2-60
Functional Description
To use one of the configurations mentioned above in a host adapter
board design, put 4.7 K
Ω
pull-up resistors on the MAD pins
corresponding to the available memory space. Each MAD pin has an
internal static pull-down; therefore, no external pull-down resistors are
needed. For example, to connect to a 64 Kbytes external ROM use a
pull-up on MAD[2]. If the external memory interface is not used,
MAD[3:1] should be pulled HIGH.
The LSI53C1000 allows the system to determine the size of the available
external memory using the Expansion ROM Base Address register in the
PCI configuration space. For more information on how this works, refer
to the PCI specification or the Expansion ROM Base Address register
description in
MAD[0] is the slow ROM pin. When pulled up it enables two extra clock
cycles of data access time to allow use of slower memory devices. The
external memory interface also supports updates to flash memory.
Table 2.7
Parallel ROM Support
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,
ROM interface disabled
Содержание LSI53C1000
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 28: ...1 12 Introduction...
Страница 234: ...4 124 Registers...
Страница 314: ...6 40 Specifications This page intentionally left blank...
Страница 318: ...6 44 Specifications This page intentionally left blank...
Страница 344: ...6 70 Specifications This page intentionally left blank...
Страница 350: ...6 76 Specifications Figure 6 42 LSI53C1000 329 Ball Grid Array Bottom view...
Страница 352: ...6 78 Specifications...
Страница 360: ...A 8 Register Summary...
Страница 376: ...IX 12 Index...