Elektronika MK-72

The sequential transmission and information processing in calculators of first generations has allowed to minimize hardware expenditures and cost of production. In accordance with perfecting and lowering of cost of element base the possibility of rise of speed of calculators has appeared at usage of multwire information buses with a parallel transmission of the information. In modern calculators this possibility is realized, as a rule, by parallel information of words of the information on tetrads during clock tick appropriate transmission on each clock tick of decimal silt of fallback sexadecimal digit. Thus has appeared to possible(probable) creation on existing element base of calculators of first generations - functional hand-held computers with properties of desktop computers.

Example of a similar microcomputer with a serialparallel information communication is the experimental calculator " Elektronika MK 72 ", created, in main, on element base of the serial calculator for check of a number of architectural solutions, which can seem useful to calculators of the following generations. By the immediate purpose of creation of this calculator was the development of the experimental multifunction school calculator with minimum cost at enough high efficiency providing application as separately, and in a local network of the educational class. On the architecture and software Elektronika MK 72 can be treated to home computers, and on overall dimensions and mass (no more than 400 g) and speed - to programmed calculators at consumption of energy from external sources by power no more than 0,7 W.

In the considered(examined) calculator the information is mapped by a sequence of 16-bit words, which bits are numbered in fallback sexadecimal digits from 0 up to F, transmitted for 4 clock ticks forming microcycle of operation. Each word is defined(determined) by its address in memory. Which is convenient for writing in a fallback sexadecimal number system. In addition to the main address bus with 16 outputs the addresses of tetrads inside machine words derivated by combinations of signals 00, 01, 10 or 11, worked out in each microcycle are entered.

Such sort of data transfer allows to use one a LSI circuit (large integrated circuit) memory with 4-bit organization (ROM and EPROM) or four LSI circuits of memory with one-bit organization (RAM). The central processing unit contains the hardware screen monitor (AM) for customization of the calculator from the debug console, 16-bit arithmetic logical device (arithmetic and logic unit), 8 16-bit general-purpose registers R0... R7, block of interrupt processing, address device (??) and two 4-bit registers RG both processor state RSP and "short" register RK. The register a processor state contains single-digit fields of conditions (flags), the values 0 or which 1 depend on results of the last fulfilled command and map correspondence to zero of result of the operation, overflow or carry of result of addition. The register P0 fulfils functions of the current address register containing an instruction address, called(caused) from memory, but yet not executed, register ?7 - function of the pointer of the stack of execution of commands. The CPU through the address device installs the address on outputs of the 16-bit address bus and transfers the processed information through the 4-bit data bus by the serialparallel code 4 x 4.