Computer system having a selectable cache subsystem
First Claim
1. A computer system which includes a processor subsystem, a memory subsystem, and a cache subsystem, said cache subsystem comprising:
- a cache memory of specified dimensions coupled within said cache subsystem via slots, said slots capable of receiving an alternative cache memory of different specified dimensions;
cache memory control means for receiving an address bus bit field corresponding to a requested address from said processor subsystem and transmitting control signals to said cache memory based on said received address bus bit field, said address bus bit field providing an address within said cache memory corresponding to said address requested by said processor subsystem;
means for modifying said address bus bit field based on said dimensions of said cache memory; and
means for addressing said cache memory via said modified address bus bit field;
wherein said address bus bit field is comprised of a tag address field, a set address field and a line select field, and wherein said means for modifying said address bus bit field based on said dimensions of said cache memory further comprises means for modifying said line select address field, said tag address field and said set address field; and
wherein said means for means for modifying said address bus bit field based on said dimensions of said cache memory further comprises means for providing a duplicate of a portion of said set address field within said tag field.
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Accused Products
Abstract
A cache subsystem for a computer system which includes a cache memory and a cache control means. When the processor subsystem of the computer system requests data, information related to the location of the data within the memory subsystem of the computer is input to the cache subsystem. The control means receives an address bus bit field and transmits control signals which vary depending on the received address bus bit field to the cache memory to look for the requested data. The address bus bit field is configured based upon the dimensions of the cache memory and includes information as to where the data would be stored within the cache memory. As different cache memories are of different dimensions, means for modifying the address bus bit field generated by the cache control means based on the dimensions of the cache memory are provided so that the cache subsystem may be readily configured to operate with different sized cache memories.
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Citations
27 Claims
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1. A computer system which includes a processor subsystem, a memory subsystem, and a cache subsystem, said cache subsystem comprising:
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a cache memory of specified dimensions coupled within said cache subsystem via slots, said slots capable of receiving an alternative cache memory of different specified dimensions; cache memory control means for receiving an address bus bit field corresponding to a requested address from said processor subsystem and transmitting control signals to said cache memory based on said received address bus bit field, said address bus bit field providing an address within said cache memory corresponding to said address requested by said processor subsystem; means for modifying said address bus bit field based on said dimensions of said cache memory; and means for addressing said cache memory via said modified address bus bit field; wherein said address bus bit field is comprised of a tag address field, a set address field and a line select field, and wherein said means for modifying said address bus bit field based on said dimensions of said cache memory further comprises means for modifying said line select address field, said tag address field and said set address field; and wherein said means for means for modifying said address bus bit field based on said dimensions of said cache memory further comprises means for providing a duplicate of a portion of said set address field within said tag field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A cache subsystem having a selectable cache memory, comprising:
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a printed circuit board; means for installing a selectable one of a first removable cache memory of a first size and a second removable cache memory of a second size on said printed circuit board; a cache controller installed on said printed circuit board for receiving a series of signals corresponding to an address within said cache memory installed on said printed circuit board and generating control signals to said cache memory installed on said printed circuit board based upon said series of received address signals; means for modifying said series of address signals based on said size of said cache memory installed on said printed circuit board; and means for addressing said installed cache memory via said modified address bus bit field; wherein either said first removable cache memory or said second removable cache memory is installed on said printed circuit board and said address signal modifying means adjusts the number and order of said series of address signals transmitted to said cache controller based upon the size of said installed cache memory; wherein said first removable cache memory is comprised of a plurality of 4K×
4 static RAM chips and said second removable cache memory is comprised of a plurality of 16K×
4 static RAM chips;wherein said printed circuit board further comprising a series of groups of sockets, each said group of sockets either receiving one of said static RAMs of said first cache memory or one of said static RAMs of said second cache memory; and wherein said static RAMs of said first cache memory have a first number of connector pins and said static RAMs of said second cache memory have a second number of connector pins different from said first number of pins; and
wherein said cache subsystem further comprises jumper connector means for permitting both said static RAMs of said first cache memory and said static RAMs of said second cache memory to operate in groups of sockets which correspond to said large number of static RAM pins. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A cache subsystem having a selectable 32 Kbyte or 128 Kbyte cache memory, comprising:
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a printed circuit board; a 32 Kbyte cache memory; a 128 Kbyte cache memory; means for selectively installing said 32 Kbyte cache memory or said 128 Kbyte cache memory on said printed circuit board; a cache controller installed on said printed circuit board and configured for receiving a 31 bit address signal corresponding to an address within said installed cache memory and generating control signals to said installed cache memory based upon said received address signal; and means for generating said 31 bit address signal as an eighteen bit tag address, nine bit set address, and one bit line select address signal when said 32 Kbyte cache memory is installed and generating said 31 bit address signal as an eighteen bit tag address, nine bit set address, and three bit line select address signal when said 128 Kbyte cache memory is installed. - View Dependent Claims (25, 26, 27)
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Specification