3-22
Signal Descriptions
3.7 MAD Bus Programming
The MAD[7:0] pins, in addition to serving as the address/data bus for the
local memory interface, also are used to program power-up options for
the chip. A particular option is programmed allowing the internal
pull-down current sink to pull the pin LOW at reset or by connecting a
4.7 k
Ω
resistor between the appropriate MAD[x] pin and V
SS
. The
pull-down resistors require that HC or HCT external components are
used for the memory interface.
•
MAD[7], Serial EEPROM programmable option – When allowed to
be pulled LOW by the internal pull-down current sink, the automatic
data download is enabled. When pulled HIGH by an external resistor,
the automatic data download is disabled. Please see
and
and
Registers in
for additional
information.
•
MAD[6] – Enable B duplicate SCSI REQ/ and ACK/ signals. When
allowed to be pulled LOW by the internal pull-down current sink, the
duplicate SCSI REQ/ and ACK/ signals for channel B are disabled.
When pulled HIGH by an external resistor, the duplicate SCSI REQ/
and ACK/ signals for channel B are enabled.
•
MAD[5] – Enable A duplicate SCSI REQ/ and ACK/ signals. When
allowed to be pulled LOW by the internal pull-down current sink, the
duplicate SCSI REQ/ and ACK/ signals for channel A are disabled.
When pulled HIGH by an external resistor, the duplicate SCSI REQ/
and ACK/ signals for channel A are enabled.
•
MAD[4], INTA/ routing enable – Placing a pull-up resistor on this
pin causes SCSI Function B interrupt requests to appear on the
INTA/ pin, along with SCSI Function A interrupt requests, instead of
on INTB/. Placing a pull-up resistor on this pin also causes the SCSI
Function B Interrupt Pin register (
0x3D
) in PCI configuration space
to be programmed to 0x01 instead of 0x02.
Placing no resistor on this pin causes SCSI Function B interrupt
requests to appear on the INTB/ pin. Placing no resistor on this pin
also causes the SCSI Function B Interrupt Pin register (
) in PCI
configuration space to be programmed to 0x02.
*
Summary of Contents for LSI53C896
Page 6: ...vi Preface...
Page 16: ...xvi Contents...
Page 88: ...2 62 Functional Description...
Page 112: ...3 24 Signal Descriptions...
Page 306: ...6 38 Specifications This page intentionally left blank...
Page 310: ...6 42 Specifications This page intentionally left blank...
Page 338: ...6 70 Specifications Figure 6 40 LSI53C896 329 BGA Bottom View...
Page 340: ...6 72 Specifications...
Page 346: ...A 6 Register Summary...
Page 362: ...IX 12 Index...