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PARALLEL DATA

Type 0x60, Parallel Data, Format 0

Parallel Data, Format 0 packets are used to record data bits received from a discrete parallel data interface. The number of bits that comprise one data word can range from 2 to 128 bits in length. A parallel data packet can contain multiple parallel data words.

The Digital Cartridge Recording System (DCRsi) recording method and digital data interface were developed by Ampex Data Systems. The DCRsi tape recording method is a transverse scan method with the tape heads embedded in the outer edge of a spinning disk placed perpendicular to the path of the tape. Data, as recorded on the DCRsi cartridge, is organized into discrete blocks, each assigned a unique address number and time stamped as it arrives at the recorder interface. The addressable block size is 4356 bytes. The electrical interface is byte-wide differential emitter-coupled logic (ECL). A simplified depiction of the interface is shown below.

DCRsi interface.

The layout of the CSDW is shown in Figure 6-51. The uType field indicates the type or size of parallel data stored. For values between 2 and 128, uType indicates the number of bits per parallel data word. The value 254 indicates the parallel data is in DCRsi format. Other values are reserved. When the data type is not DCRsi the uScanNum field is reserved and will have a value of 0x00. When the data type is DCRsi, the uScanNum field contains the scan number value of the first scan stored in the packet for DCRsi data.

struct SuParallelF0_ChanSpec 
    { 
    uint32_t    uScanNum    : 24;   // Scan number 
    uint32_t    uType       :  8;   // Data type 
    }; 

Type 0x60 Parallel Data Format 0 CSDW.

Recorded parallel data follows the CSDW. There is no intra-packet header. For general purpose packets, bit padding is used to align recorded data on byte or word boundaries. There is no count for the number of parallel data words following the CSDW. This must be calculated from the data length in the header and the number bytes per data word. See the Chapter 10 standard for complete details.


Type 0x61 - 0x67, Parallel Data, Format 1 - Format 7

Reserved for future use.

ch10_handbook/parallel_data.txt · Last modified: 2014/05/29 14:42 by bob