Download Sharp YO-470 Service manual

The following address check is performed further.
Check point address = 1C0000H, 1C0001H
1C0002H, 1C0004H
1C0008H, 1C0010H
1C0020H, 1C0040H
1C0080H, 1C0100H
1C0200H, 1C0400H
1C0800H, 1C1000H
1C2000H, 1C4000H
1C8000H, 1D0000H
[12] Standard RAM test
1 Key operation
120 → TL
2 Functional description
Perform the following check for the standard RAM 32 KByte
SRAM. The memory contents should not be changed before and
after the check.
Perform the following processes for memory address to be
checked (1C0000H~1DFFFFH).
PASS1: Save memory data.
PASS2:
PASS3:
PASS4:
PASS5:
PASS6:
S
DOT DISPLAY:
Write data "0000H."
Read and compare data "00H," write data "55H."
Read and compare data "55H," write data "AAH."
Read and compare data "AAH."
Restore the memory data.
R A M
7-SEGMENT DISPLAY:
If a compare error occurs in the check sequence PASS1-PASS6,
an error print is made. If no error occurs through all address, the
check ends normally.
Operation flow
Check address
table
Initialize the table pointer
START
Read check address from the
address table by pointer
sccess
Table pointer
Save data of check address
to the CPU register
Write data 55H to check
address
END
For check address other than
the current check address,
write AAH after saving 1-byte
data into the register
Is the
current check
address 55H?
NO
YES
Reset operation of saved data
NO
Is the
operation comleted
for the other check
address?
YES
Revise the table pointer
NO
Is the
address table
completed?
YES
End
– 36 –
Address
error
T S
S R V