32×32 shared buffer type ATM switch VLSIs for B-ISDN

A set of 0.8 μm CMOS VLSIs developed for shared buffer switches in asynchronous transfer mode (ATM) switching systems is described. A unit switch, whose size is 32×32, consists of 8 buffer memory LSIs (BFM-LSIs), 2 memory control LSIs (CTRL-LSIs) and 2 commercially available first in, first out (FIFO) memory LSIs. Using these VLSIs, the 32×32 switch can be mounted on a printed board. This switch is a shared buffer switch. It achieves buffer memory utilization improvement through the use of buffer sharing among all output ports of the switch and has a large 2-Mbit shared buffer which can save 4096 cells. As a result, this switch can satisfy the cell loss rate requirements, not only under random traffic conditions but also under burst traffic conditions. The switch has a priority control function to meet the requirements for various media. It is useful for multimedia ATM networks