Computer with probability means to transfer pages from large memory to fast memory

Claim 2

In a computer system in which memory words are grouped in pages of memory words, a relatively fast, small random-access memory, a large, relatively slow, directly-addressable, random-access memory, means to determine whether a desired memory word is located in the fast memory or the large memory, first means operative when the desired memory word is located in the fast memory to directly address the fast memory, and second means operative when the desired memory word is located in the large memory to directly address the large memory a large percentage of the time and which includes means to transfer a page of memory words including the desired word from the large memory to the fast memory a remaining small percentage of the time.

Claim 3

The combination as defined in claim 1 wherein said second means includes a random probability means for making each decision to directly address the large memory or to transfer a page from the large memory to the fast memory in a random manner, rather than in a predetermined manner.

Claim 4

The combination as defined in claim 2 wherein said random probability means includes a random number source and means to compare the magnitude of the number from the source with a predetermined number.

Claim 5

The combination as defined in claim 1 wherein said second means includes a random number source and means to determine whether a random number from said source is greater or less than a predetermined value.

Claim 6

The combination as defined in claim 1, and in addition, means to limit the maximum number of pages which can be transferred from the large memory to the fast memory.

Claim 7

In a computer system in which memory words are grouped in pages of words, the combination of a fast, small random-access memory, a large slow directly-addressable, random-access memory, a real address register for the address of a memory word to be accessed from either one of said memories, an address comparator receptive to the contents of said real address register and having a first output indicating a storage location in said fast memory, and having a second output representing a storage location in said large memory, means responsive to said first output of said address comparator to employ the contents of said real address register to address the fast memory, a probability means having a first output which is energized a very large proportion of the time and a second output which is energized the remaining small proportion of the time, means responsive to said second output of said address comparator and the first output of sAid probability means to employ the contents of said real address register to address the large memory, and means responsive to said second output of said probability means and the contents of said real address register to interrupt the computer and cause a transfer from the large memory to the fast memory of a page of memory words including the memory word specified by the contents of said real address register.

Claim 8

In a computer system in which memory words are grouped in pages of words, the combination of a fast, small random-access memory, a large slow directly-addressable, random-access memory, a real address register for the address of a memory word to be accessed from either one of said memories, an address comparator receptive to the contents of said real address register and having a first output indicating a storage location in said fast memory, and having a second output representing a storage location in said large memory, means responsive to said first output of said address comparator to employ the contents of said real address register to address the fast memory, a probability means having a first output which is energized a very large proportion of the time and a second output which is energized the remaining small proportion of the time, means responsive to said second output of said address comparator and the first output of sAid probability means to employ the contents of said real address register to address the large memory, and means responsive to said second output of said probability means and the contents of said real address register to interrupt the computer and cause a transfer from the large memory to the fast memory of a page of memory words including the memory word specified by the contents of said real address register.

Claim 9

A system as defined in claim 6 wherein said probability means is a random probability device for making each decision to directly address the large memory or to transfer a page from the large memory to the fast memory in a random manner.

Claim 10

A system as defined in claim 7 wherein said probability device includes a random number source and means to determine whether a random number from said source is greater or less than a predetermined value.

Claim 11

A system as defined in claim 6, and in addition, means to limit the maximum number of pages that can be transferred to the fast memory.