The functions of the data grabber can be summarized as:
a) Collect serial data from the LV-ROM decoder.
b) Convert the two streams of serial data to parallel form
c) Establish lock with the block structure
d) Read the header
e) When the desired header is seen, store that block and the two following blocks in RAM
f) Signal to the CPU that the header and the following three blocks are ready
During this sequence the data is unscrambled and if error flags are present the CPU enters a correction routine to recover corrupt data.