Sharp PC-4741 Service Manual page 36

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P C-4741
8·5·1·1. Real Time Clock & Setup RAM Check
_" Memory Check
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2 --- Video memory check
When this test item is chosen, the sUb-menu shown below appears. 3 --- EMS memory check
The desired test item must be chosen by typing the number in the 0 --- Exit
menu.
If 0
is typed, the control returns to the individual devices diag- Enter your selected number: _
nostic menu.
Real Time Clock
&
Setup RAM Check
1 --- Real time clock check
2 --- Setup RAM check
o ---
Exit
Enter your selected number:_
Real Time Clock
&
Setup RAM Check Menu
After a test item was chosen, the control comes asking for a
parameter option entry before going into the test. And the test
will
start after this. If no error was encountered, test repetitions are con-
tinued to count.
Depression of the ESC key terminates the test.
When an error was encountered, the error message is produced.
• Real time clock check
This test item tests the real time clock within the sub-CPU for a period
of one second while communicating with the sub-CPU by means of
the V40 timer interrupt (18.2Hz).
• Setup RAM check
Except for the RAM area within the sub-CPU where the date and time
are stored, this test program communicates with the sub-CPU and
tests the setup RAM area in the read/write mode in the following
manner:
1. Data "5" is written in the setup RAM check area.
2. This data "5" stored in the setup RAM is read one digit at a time,
then the data "A" is written in every area until the entire area is
written with" AI!.
3. This test data "A" is read one digit at a time, then the data "5" is
written in every area until the entire area is written with "5".
The contents of the setup RAM are saved prior to initiation of the test
and restored after completion of the test.
Error message
• REAL TIME CLOCK ERROR
The real time clock in the sub-CPU or the V-40 timer is not working
properly.
• SETUP RAM READIWRITE ERROR
The test data written in the setup RAM within the sub-CPU does
not coincide with the data written.
• INTERPROCESSOR COMMUNICATION ERROR
Communication is not done properly with the sub-CPU.
• SETUP RAM BROKEN ERROR
The contents of the setup RAM are destroyed as a result of a
communication failure with the sub-CPU during the test of the
setup RAM.
8·5·2. Memory Check
This program tests the main memory and the video memory on the
main board and the EMS memory on the EMS memory card. (CE-
471 B)
The following menu appears when this test program is selected.
One of three test items must be chosen after typing the desired
number.
Typing 0
will
cause the control to return to the individual devices
diagnostic menu.
-35-
Memory Check Menu
After a test item was chosen, the control comes asking for a
parameter option entry before going into the test. as discussed in
Paragraph 5-1.
And the test will start after this.
If no error was encountered, test repetitions are continued to count.
Depression of the ESC key terminates the test.
When an error was encountered, the error message is produced.
• Main memory check
This program tests for 640KB of the main memory.
1. The main memory area after the address 30000H is read/write
tested using the marching test mode in an increment of 64KB.
2. If not error was encountered after checking the area after the
address 20000H, the data in the address OOOOOH through
2FFFFH are copied onto the area after the address 30000H, then
the address OOOOOH through 2FFFFH is tested in the marching
test mode in an increment of 64KB.
Video memory
This program tests for 128KB of the video memory.
The video memory area is read/write tested using the marching test
for four video DRAM bank (32KB).
Note that care was taken by the program not to destruct the video
memory contents.
• EMS memory check
This program test for 1 MB of the EMS memory.
The EMS memory area is read/write tested using the marching test
for 64 page frame (16KB).
Note that care was taken by the program to destruct the EMS
memory contents.
NOTE: The marching test for the main memory check and
~he
video
memory check is carried out in the following manner:
1. Test data 5555H are written in the area to be checked.
2. The test data are read at every word and the test data
AMAH are written. This is done for all the areas.
3. The data AAAAH are read at every word and the test data
5555H are written. This is done for all the areas.
4. The entire area
to
be tested is written with OOOOH.
5. The data OOOOH are read at every word and the test data
FFFFH are written. This is done for all the areas.
6. The data FFFFH are read at every word and the test data
OOOOH are written. This is done for all the areas.
Error message
• 640KB MAIN MEMORY RIW ERROR - address: XOOOH, data:
yyyyH During test of 640KB main memory area, the test data
stored in the segment address XOOOH did not coincide with read
data in a yyyyH bit pattern.
• 128KB VIDEO MEMORY RIW ERROR - bank: x, data: yyyyH
During test of 128KB video memory area, the test data stored in
the bank X did not coincide with read data in a yyyyH bit pattern.
*
1 MB EMS MEMORY FWI ERROR - address: 1 XXOOOH, data:
YYYYH During test of 1 MB EMS memory area, the test data
stored in the address from 1XXOOOH to 1XXFFFH did not conin-
cide with read data in a YYYYH bit pattern.