SCSI Registers
4-85
R
Reserved
[5:4]
SZM
SCSI High Impedance Mode
3
Setting this bit places all the open drain 48 mA SCSI
drivers into a high impedance state.
R
Reserved
[2:1]
LOW
SCSI Low Level Mode
0
Setting this bit places the LSI53C1000 in the low level
mode. In this mode, no DMA operations occur and no
SCRIPTS execute. Arbitration and selection may be
performed by setting the start sequence bit as described
in the
register. SCSI bus
transfers are performed by manually asserting and polling
SCSI signals. Clearing this bit allows instructions to be
executed in the SCSI SCRIPTS mode.
Note:
It is not necessary to set this bit for access to the SCSI
bit-level registers (
, and input registers).
Register: 0x4F
SCSI Test Three (STEST3)
Read/Write
TE
TolerANT Enable
7
Setting this bit enables the active negation portion of
LSI Logic TolerANT technology. Active negation causes
the SCSI Request, Acknowledge, Data, and Parity
signals to be actively deasserted, instead of relying on
external pull-ups, when the LSI53C1000 is driving these
signals. Active deassertion of these signals occurs only
when the LSI53C1000 is in an information transfer phase.
When performing synchronous transfers, TolerANT
should be enabled to improve setup and deassertion
times. Active negation is disabled after reset or when this
bit is cleared. For more information on LSI Logic
TolerANT technology, see
7
6
5
4
3
2
1
0
TE
R
HSC
DSI
R
TTM
CSF
R
0
0
0
0
0
0
0
0
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...