Diagonal examples for design space exploration in an educational environment City-1

City-1 is an educational environment for microcomputer design using hardware description languages (HDLs) such as VHDL and Verilog-HDL, which are used to describe specifications expected to be implemented by using field-programmable gate arrays (FPGAs). More than 40 original computers ore created within 15 weeks by junior students every year since 1996. The key aspect of this educational environment is the teaching materials to present “diagonal examples”, which are two types of HDL descriptions: (1) a horizontal microcode like state assignment for the control unit and (2) three stages fully interlocked pipelined CISC with its reservation table. These descriptions are placed diagonally with the prior (1´) shift-register like state assignment for the control unit and (2´) several stages pipelined RISC with delayed operations expressed by a data-path chart, which are familiar to the students through other course subjects. During the first three years, 140 students out of 164 students succeeded to complete entire design and fabrication phases. 76 machines were CISC and 64 machines were RISC. 93 machines out of 140 machines were from 2 to 4 stages pipelined CISC/RISC. A couple of students advanced their studies on Data-Driven Neumann Machine (DDNM) architecture in their graduation reports