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Modular Computer with Read Only Memory

IP.com Disclosure Number: IPCOM000094580D
Original Publication Date: 1965-Mar-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 4 page(s) / 73K

Publishing Venue

IBM

Related People

Hollobaugh, WF: AUTHOR [+2]

Abstract

This digital processing machine is based on the concepts of modularity and microprogramming. These concepts of the modular computer are as follows. The modular construction is carried out at the register level. There is a maximum of physical interchangeability among the modules. A changeable read-only memory should be used to store a program. Such controls the operation of the modules in order that sufficient flexibility of machine organization is obtained to permit the modularity to be used effectively. The computer is viewed as a data bus with a programmable control unit. However, the computer is not able to function without the addition of functional modules. These are in the form of registers, memories, input-output devices, and arithmetic units.

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Modular Computer with Read Only Memory

This digital processing machine is based on the concepts of modularity and microprogramming. These concepts of the modular computer are as follows. The modular construction is carried out at the register level. There is a maximum of physical interchangeability among the modules. A changeable read-only memory should be used to store a program. Such controls the operation of the modules in order that sufficient flexibility of machine organization is obtained to permit the modularity to be used effectively. The computer is viewed as a data bus with a programmable control unit. However, the computer is not able to function without the addition of functional modules. These are in the form of registers, memories, input-output devices, and arithmetic units. These modules are simple or complex, ranging from a basic data register to other digital or analog computers. In particular, this article emphasizes the simple functional modules.

The result of this modular arrangement is a great flexibility in machine organization and excellent serviceability. In order to change the nature of the machine, it is necessary only to plug in the required modules and to change the contents of the read-only memory. If a module fails, a new one can be substituted quickly. The bad module can be repaired at leisure, for example, at the manufacturing plant. Also, the detection of failures can be carried out easily with programming techniques.

A single bus arrangement of a modular machine is shown in A. Two bus arrangements are shown in B.

The microinstruction complement for these types of machines is very small. In fact, there are only three required micro-instructions. They are Move (MO), Fill
(F), and Branch (B). Each of these, when executed, can accomplish relatively little. However, each microinstruction is executed in a very short time. Thus by executing a sequence of such micro-instructions, the machine is able to obtain many results.

MO causes data to be transferred from one module to another. F transfers bits of information from the micro-instruction to a module. B is unconditional (UB) or conditional (CB). In the first case, a change in the sequence of micro- instructions is made. In the second case, the B occurs only if some aspect of the state of a given module is true.

The function of the data bus, shown in A and B, is to provide for the transfer of information from a module (M)2 to a M4, from a control unit (CU)6 to the M4, and from the M2 to CU6. This information consists of the eight bits of data as well as the necessary control and timing information required for the operation of an asynchronous machine.

CU6 provides for the control of data transfers through the interpretation of the microprogram stored in its read-only memory (ROM)8 shown in C. The contents of ROM8 are changed when new modules are added or a macro-function is to be changed. The operating speed of ROM8 is fast relative to the operating rate...