GE/PAC Magnetic Drum Emulation on an IBM PC/AT

摘要

The GE/PAC 4020 computer is being used as the process computer of Karachi NuclearPower Plant (KANUPP). A project was undertaken at the Computer Training Center (CTC) to replace the Magnetic Drum unit of GE/PAC with an IBM personal computer to eliminate the possibility of a major problem if the Drum units cannot be supported in the future. The hardware consists of two modules, one of them replaces the Drum coupler of GE/PAC and the second interfaces the former to the IBM PC/XT bus. The software developed includes the emulation of the Drum unit of GE/PAC on the extended RAM of IBM PC/AT and the provision of the handshaking signals in the GE/PAC protocol to make it functionally compatible with the Drum unit. Three copies of the Drum information are dynamically maintained on the RAM and a non volatile copy is maintained on the hard disk. Each read/write operation is performed through a 2 out of 3 integrity check for the data in the multiple copies of the Drum information.