Guralp Systems CMG-SAM - Manual (Page 22)

Operator’s Guide CMG SAM & CMG CRM
SCSI FILE ALLOCATION TABLE
The system uses the first few blocks (1 block = 2* 512 byte sectors) of the SCSI disc to
store the pointers necessary to read and write the data streams. This table consistes of
16 byte fields used as 4 long word records.
The first field contains the ‘system-id’ (the first block header record - see next section)
used to identify the disc, followed by the address (sector number) of the first data on the
disc, the address of the end of data (next free sector) and the last address on the disc.
Subsequent fields are allocated to each data stream and start with the ‘channel-id’
(second field in the block header - see next section), the start address of the stream on
disc, the address of the last block of data for this stream and the final record is used for a
read access pointer.
Disc/System-id
Start of data Start of free space End of disc
1st Stream id Start of stream End of stream Read pointer
2nd Stream id Start End Read
3rd Stream id Start End Read
etc ...
Issue D March 2001 20