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TM 11-6625-3145-14
Maintenance: Troubleshooting-318/338 Service
The chip select signals, RAM1CS and RAM2CS are generated by U005 (dual 2-line to 4-line decoder/multiplexer,
74LS139) on the A05 ROM/Threshold board. These signals are sent to the System RAMs through the A08 Mother board.
The MPU checks the System RAMs with the checkerboard marching pattern. The read and write sequences are
mentioned in the
Power
on section above. If the data read is incorrect, the MPU will issue an error message.
6.
ROM TEST
Program:
Function:
Power on - ROM1 through ROM6 are checked by individually calculating their checksums.
Troubleshooting - None.
Description: Refer to Figure 7-5. All the ROMs (ROM1 through ROM7) are located on the A05 ROM/Threshold board.
Table 7-3
318 ROM TEST ADDRESS ASSIGNMENT
ROM
U#
Address
Enabled by
ROM1
U020
0000-3FFF
/ROM1
ROM2
U021
4000-7FFF
/ROM2
ROM3
U022
8000-BFFF
/ROM3
ROM4
U023
8000-BFFF
/ROM4
ROM5
U024
8000-BFFF
/ROM5
ROM6
U025
8000-BFFF
/ROM6
The chip-select signals for ROM1 and ROM2 are decoded by U001 (dual 2-line to 4-line decoder/demultiplexer, 74LS139)
on the A05 ROM/Threshold board. All the other chip select signals are doubly decoded. ROM3, ROM4, ROM5, and
ROM6 are decoded by U001 B (74LS139) which is enabled by U001A (74LS 139) on the A05 board. These ROMS are
also selected by two data bits from U100 (74LS174) on the A05 board in order to constitute four pages of ROM.
The MPU reads data from these ROMs through U045 (octal bus transceiver with tri-state output, 74LS245) on the A05
board and through the A08 Mother board. The MPU addresses are sent to these ROMs and the decoders (74LS139) on
the A05 board via U210 and U212 (octal buffer/line driver with tri-state output, 74LS 244) on the A06 MPU/Display board
and through the A08 board. The MPU control signals are also provided through U214 (octal buffer/line driver with tri-state
output, 74LS240) on the A06 board and through the A08 board.
The MPU calculates the checksum for each ROM and determines whether it is correct or not. If it is incorrect, an error
message will be displayed.
7-9
Summary of Contents for 318
Page 119: ...318 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 182: ...338 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 253: ...318 ___________________ TROUBLESHOOTING TREES ...
Page 344: ...338 TROUBLESHOOTING TREES ...
Page 517: ...TM 11 6625 3145 14 318 338 4434 923 318 Block Diagram ...
Page 518: ...TM 11 6625 3145 14 318 338 4434 924 338 Block Diagram ...
Page 519: ...TM 11 6625 3145 14 318 338 4434 925 318 Acquisition Module Wiring Diagram ...
Page 520: ...TM 11 6625 3145 14 318 338 4434 926 318 338 Mainframe Wiring Diagram ...
Page 521: ...TM 11 6625 3145 14 318 338 4434 926 338 Acquisition Module Wiring Diagram ...
Page 522: ...TM 11 6625 3145 14 318 338 4434 928 Figure 9 1 318 A01 Input A Board Component Locations ...
Page 526: ...TM 11 6625 3145 14 ...
Page 528: ...TM 11 6625 3145 14 Figure 9 3 318 338 A03 ACQ Control Board Component Locations ...
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Page 542: ...TM 11 6625 3145 14 Figure 9 8 318 338 A10 CRT Board Component Locations ...
Page 544: ...TM 11 6625 3145 14 Figure 9 9 318 338 A11 Inverter Board component Locations ...
Page 546: ...TM 11 6625 3145 14 Figure 9 10 318 338 A12 Regulator Board Component Locations ...
Page 551: ...TM 11 6625 3145 14 Figure 9 12 338 A01 Input A Board Component Locations ...
Page 553: ...TM 11 6625 3145 14 318 338 SERVICE ...
Page 554: ......
Page 555: ...PIN 058584 ...