Algebraic models of microprocessors: the correctness and verification of a simple computer
N. A. Harman, John Vivian Tucker · 1998
CIRCUIT DESIGN We now consider the abstract circuit representation of Gordon's Computer. A diagram of the basic implementation is shown in Figure 3. From the implementation representation in Figure 3 we can see that the following elements have been added to the datapath, in order for it to function: A memory address register (MAR) of 13 bits, an instruction register (IR), an argument register (ARG), and a buffer register (BUF), all of 16 bits. All components of the datapath, and the memory, are connected by a 16-bit bus, though this is not properly part of the state of the datapath. The controller is seen to consist of a microprogram counter (MPC), and a microprogram memory (ROM) consisting of 32 words of 30 bits each, together with a decoder. 5.1 Controller: Informal Description Each 30-bit microprogram word consists of four fields: a three-bit test field; two five-bit next address fields, A and B; and a 17-bit control field. The control field is used to direct the operation of da...