The communication architecture of the DIMMnet-1 network interface, based on MEMOnet, is described. MEM-Onet is an architecture consisting of a network interface plugged into a memory slot. The DIMMnet-1 prototype will have two banks of PC133 based SO-DIMM slots and an 8Gbps full duplex optical link or two 448MB/s full duplex LVDS channel links. The software overhead incurred to generate a message is only 1 CPU cycle and the estimated hardware delay is less than 100ns using the atomic on-the-fly sending with header TLB. The estimated achievable communication bandwidth with block on-the-fly sending with protection stampable window memory is 440MB/s which was observed in our experiments writing to the DIMM area with a write combining attribute. This is 3.3 times higher than the maximum bandwidth of PCI. This high performance distributed computing environment is available using economical personal computers with DIMM slots.