446 EVOLUTION OF COMPUTER BUILDING BLOCKS

The first control step reads T to register N (N¬ T). The second step initializes the sum S (S ¬ 0). The inner loop consists of the three functions: S ¬ S+N; N¬ N-l; and a test for N=0.

Example: A Small Stored Program Computer Design Using RTMs
Figure 4 shows an RTM diagram for a small stored program computer that was initially constructed as an application experiment to demonstrate the feasibility of the modules and to investigate systems problems. The process of specifying the machine took approximately two hours (with three people). The computer was wired and, aside from minor system/circuit problems (for which the experiment was designed), the computer operated essentially when power was applied because there were no logic

Figure 4. RTM design of a small stored program digital computer.