~~ODT~~
===== 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.
{{ :ch10_handbook:dcrsi_interface.png?nolink |}}
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.