SCSI Functional Description
2-45
Figure 2.5
Determining the Synchronous Transfer Rate
2.2.16 Interrupt Handling
The SCRIPTS processor in the LSI53C1000 performs most functions
independently of the host microprocessor. However, certain interrupt
situations must be handled by the external microprocessor. This section
explains all aspects of interrupts as they apply to the LSI53C1000.
2.2.16.1 Polling and Hardware Interrupts
The external microprocessor is informed of an interrupt condition by
polling or hardware interrupts. Polling means that the microprocessor
must continually loop and read a register until it detects a bit that is set
40 MHz
Clock
Quadrupler
SCF
Divider
Asynchronous
Divider
Asynchronous
SCSI Logic
Divide by 4 (ST)
SCF2
SCF1
SCF0
SCF Divisor
0
0
0
3
0
0
1
1
0
1
0
1.5
0
1
1
2
1
0
0
3
1
0
1
4
1
1
0
6
Receive/Send
Divide by 2 (DT)
SCLK
Rate
Received Rate (DT)
Input Clock Rate
SCF Divisor
2
×
(
)
----------------------------------------------
(Megatransfers/s)
=
Receive Rate (ST)
Input Clock Rate
SCF Divisor
4
×
(
)
----------------------------------------------
(Megatransfers/s)
=
Send Rate (DT)
Input Clock Rate
SCF Divisor
2
XCLKS_DT
XCLKS_ST
XCLKH_DT
XCLKH_ST
+
+
+
2
-----------------------------------------------------------------------------------------------------------------------------------------------
+
×
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
=
Send Rate (ST)
Input Clock Rate
SCF Divisor
4
XCLKS_ST
XCLKH_ST
+
+
(
)
×
-------------------------------------------------------------------------------------------------------------------------
=
Содержание LSI53C1000
Страница 6: ...vi Preface...
Страница 16: ...xvi Contents...
Страница 28: ...1 12 Introduction...
Страница 234: ...4 124 Registers...
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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...