CY7C964A

Use with Cypress VMEbus Controllers

The CY7C964A Bus Interface Logic Circuit is a seamless interface between the VIC068A/VIC64 and the VMEbus signals. The device functions equally well in the established 32-bit VMEbus arena and the new 64-bit VMEbus standard. The device contains three 8-bit counters to fulfill the functions of Block counters, and DMA counters as implied by the D64 portion of the VMEbus specification. It also contains the necessary multiplexing logic to allow the 64-bit-wide VMEbus path to be funnelled to and from the 32-bit local bus. Control circuitry is included to manage the switching of the 32-bit address bus during normal (32-bit) operations, and during MBLT (64-bit) operations. The on-chip drivers are capable of driving the VMEbus directly (48 mA).

Use in Other VMEbus Controller Implementations

The CY7C964A circuitry is designed to be of use to designers of VMEbus circuitry, including VSB (VME subsystem bus) and designs not requiring the features of the Cypress VIC068A, VIC64, and CY7C960A. The logic diagram includes general- purpose blocks of comparators, counters, and latches that can be controlled using the flexible control interface to allow many different options to be implemented. Although the device is offered in a small 64-pin package, the use of multiplexed input and output pins provides access to the many internal functions, thus saving external circuitry.