![Tektronix CSA7404B Service Manual Download Page 300](http://html1.mh-extra.com/html/tektronix/csa7404b/csa7404b_service-manual_1077968300.webp)
Troubleshooting
6- 80
CSA7404B, TDS7704B, TDS7404B, TDS7254B & TDS7154B Service Manual
Table 6- 9: POST codes (Cont.)
Displayed
error code
Error message
Displayed
error code
Error message
4Bh
Amount of memory above 1M found and verified. (If
power on, go to check point 4Eh).
D4h
Verify base memory.
4Ch
Memory below 1M cleared. (SOFT RESET)
D5h
Copy initialization code to segment 0 and transfer
control to segment 0.
4Dh
Memory above 1M cleared. (SOFT RESET) Going
to save the memory size. (Go to check
point # 52h).
D6h
Control is in segment 0. To check recovery mode
and verify main BIOS checksum. If either it is
recovery mode or the main BIOS checksum is bad,
go to check point E0 for recovery, else go to check
point D7 for giving control to main BIOS.
4Eh
Memory test started. (NOT SOFT RESET)
D7h
Find Main BIOS module in ROM image.
4Fh
Memory size display started. This will be updated
during memory test. Going for sequential and
random memory test.
D8h
Uncompress the main BIOS module.
50h
Memory testing/initialization below 1M complete.
D9h
Copy main BIOS image to F000 shadow RAM and
give control to main BIOS in F000 shadow RAM.
51h
Memory size display adjusted due to relocation/
shadow.
E0h
On-board Floppy Controller is initialized. Com-
pressed recovery code is uncompressed in
F000:0000 in Shadow RAM and give control to
recovery code in F000 Shadow RAM. Initialize
interrupt vector tables, initialize system timer,
initialize DMA controller and interrupt controller.
52h
Memory testing/initialization above 1M complete.
E8h
Initialize extra (Intel Recovery) Module.
53h
Memory size information is saved. CPU registers
are saved.
E9h
Initialize floppy drive.
54h
Shutdown successful, CPU in real mode.
EAh
Try to boot from floppy. If reading of boot sector is
successful, give control to boot sector code.
57h
A20 address line, parity/NMI disable successful.
EBh
Booting from floppy failed, look for ATAPI (LS-120,
Zip) devices.
58h
Memory size adjusted for relocation/shadow.
ECh
Try to boot from ATAPI. If reading of boot sector is
successful, give control to boot sector code.
59h
Hit <DEL> message cleared. <WAIT .> message
displayed.
EFh
Booting from floppy and ATAPI device failed. Give
two beeps. Retry the booting procedure again; go
to check point E9).
60h
DMA page register test passed.
While control is inside the different bus routines, additional checkpoints are
output to port 80h to identify the routines. In these checkpoints, the low byte of
the checkpoint is the system BIOS checkpoint from which the control is passed
to the different bus routines. The high byte of the checkpoint indicates which
routine is being executed. Table 6--10 describes which function being executed.
Summary of Contents for CSA7404B
Page 4: ......
Page 14: ...Table of Contents x CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 18: ...Service Safety Summary xiv CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 20: ...Environmental Considerations xvi CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 23: ...Specifications ...
Page 24: ......
Page 55: ...Operating Information ...
Page 56: ......
Page 69: ...Theory of Operation ...
Page 70: ......
Page 74: ...Theory of Operation 3 4 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 75: ...Performance Verification ...
Page 76: ......
Page 80: ...Performance Verification 4 4 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 92: ...Brief Procedures 4 16 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 120: ...Performance Tests 4 44 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 215: ...Adjustment Procedures ...
Page 216: ......
Page 218: ...Adjustment Procedures 5 2 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 219: ...Maintenance ...
Page 220: ......
Page 228: ...Maintenance 6 8 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 308: ...Troubleshooting 6 88 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 310: ...Repackaging Instructions 6 90 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 311: ...Options ...
Page 312: ......
Page 319: ...Replaceable Electrical Parts ...
Page 320: ......
Page 322: ...Electrical Parts List 8 2 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...
Page 323: ...Diagrams ...
Page 324: ......
Page 327: ...Replaceable Mechanical Parts ...
Page 328: ......
Page 348: ...Mechanical Parts List 10 20 CSA7404B TDS7704B TDS7404B TDS7254B TDS7154B Service Manual ...