Brief Description Of Check Procedures - Sony DVP-K800D Service Manual

5-2-4. Brief Description of Check Procedures

The diagnostic check procedures of each item are briefly describes in the order of menu.
(2) Memory
(2-2) ROM check
Checksum calculation
Error: Error is not detected.
8-bit data is added to the respective addresses of ROM starting from 0x00000 to 0xfffff. Result of the calculation is displayed in
hexadecimal number using 4 digits. Error is not detected. Compare the calculated values with the default values.
(2-3) RAM check (DMA is used)
ROM→RAM check (DMA): Check if read/write data agree.
Error 05: Write and read data do not agree.
Data of external RAM of SH is saved to stack in units of 256 bytes. After transferring the ROM data to DMA, the ROM data is read out
from DMA and compared with the ROM data in units of one byte. When the more detailed check is selected, the read-out data is bit-
inverted which is written and checked again.
During when checking is being performed, all interrupts are stopped. In addition to it, the variables use stack only including saving area
and bit inversion buffer. Because all processings are performed within this function, DAM is used for all processings including data
transfer with the stack area. When the more detailed check is selected, all areas are checked twice using the inverted data.
However, when one block is checked, the succeeding four blocks are not checked in the simple check. The check using the inverted
data, is also not performed in the simple check. If write data and read data do not agree., check can be repeated.
(3) Destination setting
(3-2) Destination setting check
I/O port reading
Error: Error is not detected.
Data of the destination setting port (I/O) is read and displayed in hexadecimal number.
Error is not detected
(4) Gate array (62000CFh: Peripheral Access Control)
(4-2) Register
Data write→Data read Check if data agrees
Error 05: Write data and read data do not agree.
Register (Peripheral Access Control) of adrs = 62000CFh
The "Data write-then-read agreement check" is performed. If write and read data do not agree., check can be repeated.
(4-3) Reset line
Data write→Resetting hardware→Data read
Error 02: Reset error
Data 0xff is written into the register (Peripheral Access Control) of adrs = 62000CFh. Then check to see that the register is initialized to
"0x00" by reset pulse.
5-5