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Vector Graphic Dual-Mode Controller Subsystem (VEDMCS)
The Vector dual mode controller is a self contained unit on a single board .On-board memory, which is accessed through a control port, provides the high speed loading and unloading of data to and from the controller. Control and status each have two 8-bit registers accessed through data ports. After the controller receives the control signals and data in the correct format, it will automatically sequence the physical reading or writing of the disk. These features save valuable memory locations through reduced software, and spare the programmer from tedious timing requiretents.
Other features include a built in hardware generated Error Correction Code (ECC). If the single control bit "ECC on/off" is on, the ECC will be generated and inserted immediately following the data during a disk write. During a read a new ECC is calculated and compared with the one already written. If an error is detected a correction code is inserted in the ECC block immediately followng the data. In the off mode ECC is transparent. Write pre-compensation is another single control bit feature. The programmer need only determine the track number above which pre-compensation is necessary, and turn it on or off.
FD/HD Controller
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