3766532 is referenced by 76 patents and cites 6 patents.

A data processing system comprising a local storage means for storing information to be processed and operation means connected to the local storage means for performing operations, such as arithmetic and logical, on information supplied thereto. A first storage means contains a plurality of microinstructions each having an operation code which are selected by addressing means connected to the local store. A second storage means contains a plurality of words which are selected by an addressing means connected to the first storage means which supplies a current address of the highest priority from a plurality of address sources, one of which includes the operation code of the selected microinstruction. A control means receives selected words gated from the second storage means and for each word provides control functions of a first type having a particular execution time duration and of a second type comprising a plurality of portions presented in a sequence during the word, the portions having equal execution time durations which in sum equal the time duration of the control functions of the first type. The control functions are connected to various parts of the system for example to gate buses to and from the local store and other parts, to select particular arithmetic and logical operations, and to control the addressing means.BACKGROUND OF THE INVENTIONThis invention relates to digital data processing systems, and more particularly to a microprogram computer having two levels of program control.Digital computers operate in accordance with a sequence of instructions known as a program which is selected and arranged by the programmer or operator of the computer to solve particular problems. The program for the computer can be separated into a set of machine operations such as addition, multiplication, and the like, which are at the programmer's disposal. Inside the machine, these machine operations can be separated into a set of micro-operations such as shifting, counting, word transfer and the like, which are at the machine designer's disposal. A portion of each machine language instruction in the machine is a number called the operation code, and this number is sent to the machine control unit to select one of a number of possible execution sequences. Originally these sequential machine operations were controlled by the wired-in logic of the computer, and the programmer was unable to alter the machine instructions made available to him.In recent times digital computers have been constructed according to the concept of microprogramming whereby wired-in logic of the machine, and hence the internal machine instructions, can be readily modified to provide the programmer with more flexibility. The concept of microprogramming, briefly, is the changing of the basic operations that take place during each clock interval of sequence of the basic machine operations. In a microprogram computer, the operation code of a machine instruction is used as an address into a fast control memory or control store. The microprogram starting at that address is executed to achieve the desired control function. As a result, machine instructions, and hence the functional nature of the computer as seen by the programmer, are determined by the microprogrammer, and may be redefined as readily as the control store may be reprogrammed.SUMMARY OF THE INVENTIONIt is a primary object of the present invention to provide a new and improved microprogram computer which is capable of extremely flexible and high speed operation.It is a further object of the present invention to provide such a computer which allows the user to define system instructions and architecture and if desired also dynamically at the system speed.It is a further object of the present invention to provide such a computer which is capable of parallel operation with a relatively large number of data paths.It is a further object of this invention to provide such a computer which achieves a useful compromise between horizontal and vertical microprogramming.It is a further object of this invention to provide such a computer wherein the instructions co-operate in a manner providing a flexible combination of instantaneous and residual control.It is a further object of the present invention to provide such a computer which is capable of emulating other machines.The present invention provides a data processing system including a first storage means for storing a plurality of instructions each including an operation code and wherein words are fetched from a second storage means in a manner utilizing the operation code of instructions selected from the first storage means. A control means receives words gated from the second storage means for providing control functions to control the system, the control means providing control functions of a first type and control functions of a second type, the functions of the second type changing while the functions of the first type remain constant. In particular, the control functions of the first type have a particular execution time duration and the control functions of the second type comprise a plurality of portions which are presented in a sequence, these portions having time durations which in sum equal the time duration of the control functions of the first type.

Title
Data processing system having two levels of program control
Application Number
05/248,689
Publication Number
3766532
Application Date
April 28, 1972
Publication Date
October 16, 1973
Inventor
Liebel Jr John T
Assignee
Nanodata Corporation
IPC
G06f 09/10
G06f 13/00
G06F 09/22
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