Analysis of Basic Problems in Design of Medium-scale Integrated Circuits in MOS Integrated Circuits

The system configuration and characteristics of the machine using MOS integrated circuits are described above. Next, we will discuss some basic issues in the development of high-integration medium-scale integrated circuits.

Medium-scale integrated circuits are related to large-scale integrated circuits and should be described first. The fundamental reason why MOS integrated circuits can exert their own strengths and surpass traditional components (transistors, bipolar integrated circuits) is that they can easily achieve a relatively high integration level. Now let's consider the most suitable machines for using MOS integrated circuits—a desktop computer or a small computer. At the beginning, the large-scale integrated circuit was divided into the whole machine according to the most average integration level and the most average number of leads, while the medium-scale integrated circuit was developed by integrating the functional unit components. MOS medium-scale integrated circuit design. This shows that the two also have the purpose of high integration, and they can coexist. However, as mentioned above, the main purpose of the medium-scale integrated circuit is the integration of functional unit components, so the medium-scale integrated circuit in the system configuration has certain limitations.

Here, a desktop computer is taken as an example to illustrate the selection of medium-scale integrated circuit functions and the characteristics of the system that introduces medium-scale integrated circuits.

In order for any desktop computer to perform its functions as a computer, it should have the necessary functions. When considering the economy of medium-scale integrated circuits or the possibility of mass production, it is appropriate to integrate the necessary functions first. MOS medium-scale integrated circuit design. In this sense, the necessary functions are described below, and the selection method of medium-scale integrated circuits is described in conjunction with specific examples. There are:

(A) A device that converts non-synchronized input signals into computer internal signals;

(B) Shift registers and memory circuits that perform operations;

(C) An adder that performs calculations;

(D) A device that converts computer signals into decimal numbers (glow discharge display tube circuit);

(E) An adder that performs decimal point operations.

Each part is described as follows.

(1) Generally, the key signal is used as the signal source. Because it instructs the work of the computer, it is called the initial pulse generator. The starting pulse generator is required to have the following basic functions:

(I) Transform the asynchronous signal (key signal) into a signal synchronized with the computer (P);

(Ii) The key signal generally has cross and distortion, so it should be able to fully prevent such cross distortion;

(Iii) The signal (P) synchronized with the computer can be controlled inside the computer, and so on.

(2) The shift register storage circuit can temporarily store information, which determines the function of the computer, so it is not possible to carry out medium-scale integrated circuits in only one form.

At present, desktop electronic computers are almost all serial operations, with effective digits of 8, 10, 12, 14, 16, 20, etc. Therefore, the scale of medium-scale integrated circuits varies depending on which level it is applicable to. 8-bit and 10-bit computers can add 4-bit shift registers. Medium-scale integrated circuits for computers with more than 12 bits are the most valuable in use. In other words,

(I) 16 bit shift odd register.

(Ii) 48-bit shift register.

(Iii) 64-bit shift register.

Most suitable for medium-scale integrated circuits. The system at this time is composed of the following components.

12-bit computer... 48-bit shift register

14-bit computer... …48 bit shift register + 4 bit shift register

16-bit computer... 48-bit shift register + 16-bit shift register or 64-bit shift register

20-bit computer... …48-bit shift register+16-bit shift register+16-bit shift register

(3) The function of the adder is mainly based on binary-decimal or pure binary operation, and the following basic functions are required.

(I) Two-decimal arithmetic can be carried out (can be corrected)

(Ii) Pure binary operations can be performed

(Iii) The conversion of addition and subtraction is possible

(Iv) Internal feedback can be separated by external signal

(4) As mentioned above, the two-decimal number or pure binary number is converted into a decimal number to represent the calculation result of the computer. MOS medium-scale integrated circuit design. There are also printer-type desktop computers, but now mainly display-type desktop computers. Therefore, it is advisable to carry out medium-scale integration of the glow discharge display tube circuit, and the following functions must be provided at this time.

(I) The display tube is a high-voltage glow discharge tube, which should be fully guaranteed to have pressure resistance.

(Ii) A current that can make the display tube emit a specified brightness.

(Iii) In order to control the glow discharge state of the display tube (zero suppression circuit or circuit to prevent repeated glow discharge), there should be an external control terminal.

(5) The decimal point calculation can be performed completely independently. Its circuit is called a decimal adder and has the following basic functions.

(I) There are two registers inside

(Ii) Ability to perform decimal point calculations required by desktop computers

(Iii) The calculation period can be selected arbitrarily

(Iv) The content of the first register can be changed to a digital signal to fetch

(V) The carry trigger can be controlled by an external signal

Below we describe the characteristics of the system when the above-mentioned medium-scale integrated circuits are introduced.

First of all, as the number of components decreases, it is expected that the number of processes will be reduced, the reliability will be improved, and the device will be miniaturized. In addition, from the point of view of structuring the system, its advantage is that a rather complicated system can be housed in a housing, such as reliable inspection of medium-scale integrated circuits, which can reduce circuit failures.

In summary, a medium-scale integrated circuit is a circuit that integrates all the necessary functions of a desktop computer into components. Due to the wide range of use of medium-scale integrated circuits, they have similarities in manufacturing and maintenance, so they are different from large-scale integrated circuits, and are convenient and highly integrated.

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