... 26 Issue 116 March 20 00 CIRCUIT CELLAR®www.circuitcellar.com Building a RISC System in an FPGA FEATUREARTICLEJan GrayiTo kick off this three- part article, Jan’s go-ing to port a Ccompiler, ... the datapath area be-cause the adder, with the immediatemux, can do the effective address add,and the PC incrementer can also addbranch displacements. The memoryaddress mux can help load the ... adds B to A, or subtractsB from A, according to its ADD input.It reads carry -in (CI) and drives carry-out (CO), and overflow (V). ADDSUBis an instance of the ADSU16 librarysymbol, and is 10...