Abstract: A byte swapping circuit which selectively orders the bytes of a 16 or 32 bit word to enable proper transmission of data between an AT computer and a VMEbus. The byte swapping circuit generally includes first, second, third and fourth groups of buffers which are disposed in parallel along an internal bus of the circuit. The first group of buffers swaps the bytes of a word having bytes A, B, C and D into the order D, C, B and A. The second group of buffers transmits a word having bytes A, B, C and D in the same order without any byte swapping. The third group of buffers swaps the bytes A and B of a 16 bit word into the order B, A. The fourth group of buffers shifts the C and D bytes of a 32 bit word, which would normally occupy bit positions 16-31, into bit positions 0-15. A control register selectively enables one group of buffers at a time to effect the needed byte swapping.

Abstract: The interconnection device attaches to the VMEbus backplane and implements a fully functional AT-compatible computer which is capable of acting as either a master or a slave on the VMEbus. The interconnection device defines a 64K window within the real mode address space of the AT computer which is mapped onto the VMEbus to allow the AT computer to access the VMEbus when in real mode. When the AT computer is in protected mode, addresses above the real mode/protected mode boundary are mapped onto the VMEbus address space. The interface apparatus modifies the AT architecture direct memory addressing (DMA) scheme to allow the microprocessor of the AT computer to act as a VMEbus slave when predefined addresses on the VMEbus are accessed.

Abstract: An industrial computer system comprising a video monitor, a plurality of computer cards, a pair of disk drive units, and power supply circuitry contained within a single cabinet. The computer cards, disk drives, and power supply circuitry are mounted in a drawer assembly that is readily removeable from the rear of the cabinet. Locator pins are affixed to the front end of the drawer assembly and are adapted to automatically engage a pair of holes located toward the front of the cabinet as the drawer is inserted into the cabinet. When inserted, the rear of the drawer assembly is bolted to the backpanel of the cabinet. Electrical connections between the components in the drawer assembly and the system are also made automatically as the drawer is inserted into the cabinet.

Abstract: A computer system employs a CPU interconnected to a number of devices and terminals over a common bus. Each device has a different address assigned to it and a message from one device to another, over the bus, is prefixed with the receiving device's address. To simplify the hardware of input/output devices connected to the system all such devices have an abbreviated address and a prefix common to the class. A decoder detects when this prefix is transmitted on the address bus and sends a signal over a line that connects only to these devices. When the devices receive a signal on this line they examine the abbreviated portion of the address and are activated when coincidence is detected.