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Section 23 CD-ROM Decoder
R01UH0134EJ0400 Rev. 4.00 Page 1245 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
Input data
Sync code
detection
Output data
Sector 1
Abnormal sector
Abnormal
sector
Maintain Ignore Maintain
Re-synchronization
Abnormal
sector
Sector 1 Sector 4
Sector 3 Sector 4 Sector 5
Figure 23.10 Operation in Automatic Sync Maintenance Mode
(When an Abnormally Long Sector is Encountered)
(2) External Sync Mode
In external sync mode, synchronization is always based on the sync codes in the incoming data.
Even if the next sync code is not detected at the 2352nd byte, decoding does not proceed until the
next sync code is detected.
Accordingly, this mode is effective in that it strictly follows the external synchronization timing.
Note, however, that decoding will not be performed normally when the sync-code pattern is input
with abnormal timing.
Figure 23.11 shows the operation in external sync mode.
Abnormal
sector
Sector 1 Sector 3 Sector 4
Input data
Sync code
detection
Output data
Sector 1 Sector 3 Sector 4 Sector 5
Abnormal sector
Figure 23.11 Operation in External Sync Mode