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| United States Patent | 5532954 |
| Link to this page | http://www.wikipatents.com/5532954.html |
| Inventor(s) | Bechtolsheim; Andreas (Stanford, CA);
Frank; Edward (Portola Valley, CA);
Testa; James (Mountain View, CA);
Storm; Shawn (Mt. View, CA) |
| Abstract | A full width single in-line memory module (SIMM) for dynamic random access
memory (DRAM) memory expansions. A printed circuit board having a
multiplicity of DRAM memory elements mounted thereto is arranged in a data
path having a width of 144 bits. The SIMM further includes on-board
drivers to buffer and drive signals in close proximity to the memory
elements. In addition, electrically conductive traces are routed on the
circuit board to reduce loading and trace capacitance to minimize signal
skew to the distributed memory elements. The SIMM further includes a high
pin density dual read-out connector structure receiving electrical traces
from both sides of the circuit board for enhanced functionality. The SIMM
is installed in complementary sockets one SIMM at a time to provide memory
expansion in full width increments. Finally, symmetrical power and ground
routings to the connector structure ensure that the SIMM cannot be
inserted incorrectly, wherein physically reversing the SIMM in the
connector slot will not reverse power the SIMM. |
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Title Information  |
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Drawing from US Patent 5532954 |
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Single in-line memory module |
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| Publication Date |
July 2, 1996 |
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| Parent Case |
This application is a continuation application of Ser. No. 08/345,477,
filed Nov. 28, 1994, now U.S. Pat. No. 5,465,229, which is a continuation
of Ser. No. 08/279,824, filed Jul. 25, 1994, now U.S. Pat. No. 5,383,148,
abandoned, which is a continuation of Ser. No. 08/115,438, filed Sep. 1,
1993, now U.S. Pat. No. 5,270,964, which is a continuation of Ser. No.
07/886,413, filed May 19, 1992.
This application is related to U.S. Pat. No. 5,260,892, entitled `High
Speed Electrical Signal Interconnect Structure`, issued Nov. 9, 1993, and
U.S. Pat. No. 5,266,218, entitled `Bus Architecture for Integrated Data
and video Memory`, issued Nov. 23, 1993. |
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Title Information |
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References |
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| *references marked with an asterisk below are user-added references |
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U.S. References |
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| | Reference | Relevancy | Comments | Reference | Relevancy | Comments | 5383148
Testa
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Takagi
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| Market Size |
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| Reasonable Royalty |
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Public's "Guesstimation" of Royalty Value
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Market Review |
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Technical Review |
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Claims |
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We claim:
1. A single in-line memory module for memory expansion in a computer system
having a memory bus with n data lines, said single in-line memory module
comprising the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connectors,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board,
wherein said electrical connector includes a full width data path;
a first set of memory elements arranged on said printed circuit board; and
a second set of memory elements arranged on said printed circuit board,
said first and second set of memory elements having a total of at least n
data lines;
a set of control signals in said electrical connector electrically coupled
to said first set of memory elements and said second set of memory
elements.
2. A single in-line memory module as claimed in claim 1 one of said single
in-line memory modules can increase a main memory in said computer system.
3. A single in-line memory module as claimed in claim 1 wherein said single
in-line memory module provides data in a first data path at least as wide
a second data path used by a central processing unit in said computer
system.
4. The single in-line memory module for memory expansion of claim 1 wherein
said first set of electrical contacts and said second set of electrical
contacts are electrically distinct.
5. A single in-line memory module as claimed in claim 1 wherein said
electrical connector has symmetrical power and ground contacts for
preventing damage to said single in-line memory module if said single
in-line memory module is inserted into said computer system backwards.
6. A single in-line memory module as claimed in claim 1 wherein said single
in-line memory module further comprises:
a driver circuit mounted substantially centered on said first side of said
printed circuit board, said driver circuit coupled to a set control
signals in said electrical connector, said driver circuit transmitting
said controls signals to said first set of memory elements and said second
set of memory elements.
7. A single in-line memory module as claimed in claim 6 wherein:
said first set of memory elements is arranged on the first side of said
printed circuit board and comprises a first subset arranged to the left of
said driver circuit and a second subset arranged to the right of said
driver circuit; and
said second set of memory elements is arranged on the second side of said
printed circuit board and comprises a third subset positioned opposite
said first subset and a fourth subset positioned opposite said second
subset.
8. A single in-line memory module as claimed in claim 7 wherein said first,
second, third, and fourth subsets of memory elements each comprise nine
memory elements arranged in a three by three matrix and said driver
circuit transmits said control signals directly to a center memory element
in said first and second memory element subsets such that signal skew is
minimized.
9. A single in-line memory module as claimed in claim 8 wherein said
control signals comprise column address strobe (CAS), row address strobe
(RAS), write enable (WE), and output enable (OE) signals.
10. A single in-line memory module as claimed in claim 9 wherein said
driver circuit further drives address lines.
11. A single in-line memory module as claimed in claim 9 wherein said
electrical connector has symmetrical power and ground contacts such that
said single in-line memory module is not damaged in said single in-line
memory module is inserted into said computer system backwards.
12. A single in-line memory module as claimed in claim 6 wherein said
single in-line memory module provides data in a first data path at least
as wide a second data path used by a central processing unit in said
computer system.
13. A single in-line memory module as claimed in claim 1 wherein said
single in-line memory module further comprises the elements of:
a second set of memory elements arranged on said printed circuit board,
said first and second set of memory elements having a total of at least n
data lines; and
a driver circuit mounted substantially centered on said first side of said
printed circuit board, said driver circuit coupled to a set of control
signals in said electrical connector, said driver circuit transmitting
said controls signals to said first set of memory elements and said second
set of memory elements.
14. The single in-line memory module as claimed in claim 1 wherein said
full width data path includes a plurality of error correction lines.
15. A single in-line memory module for memory expansion in a computer
system having a memory bus, said single in=line memory module comprising
the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said printed circuit board; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements;
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
16. The single in-line memory module as claimed in claim 15 wherein said
full width data path includes a plurality of error correction lines.-t
17. A single in-line memory module for memory expansion in a computer
system having a memory bus, said single in-line memory module comprising
the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said first side of said printed
circuit board, said first set of memory elements coupled to first set of
electrical contacts;
a second set of memory elements arranged on second side of said printed
circuit board, said second set of memory elements coupled to second set of
electrical contacts; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements;
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
18. A single in-line memory module for memory expansion in a computer
system having a memory bus, said single in-line memory module comprising
the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector having a first set of electrical contacts and a
second set of electrical contacts;
a first set of memory elements arranged on said printed circuit board; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
19. A single in-line memory module for memory expansion in a computer
system having a memory bus with n data lines, said single in-line memory
module comprising the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said printed circuit board, said
set of memory elements having a total of at least n data lines; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements;
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
20. A single in-line memory module for memory expansion in a computer
system having a memory bus with n data lines, said single in-line memory
module comprising the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of printed circuit board and a second set of electrical
contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said first side of said printed
circuit board, said first set of memory elements coupled to firs set of
electrical contacts;
a second set of memory elements arranged on second side of said printed
circuit board, said second set of memory elements coupled to second set of
electrical contacts, said first and second set of memory elements having a
total of at least n data lines; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements;
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
21. A single in-line memory module for memory expansion in a computer
system having a memory bus with n data lines, said single in-line memory
module comprising the elements of:
a printed circuitry board, said printed circuit board having a first side
and a second side, said printed circuit board having an electrical
connector, said electrical connector having a first set of electrical
contacts and a second set of electrical contacts;
a first set of memory elements arranged on said printed circuit board, said
set of memory elements having a total of at least n data lines; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements
where in said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
22. A single in-line memory module for memory expansion in a computer
system having a memory bus with n data lines, said single in-line memory
module comprising the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said printed circuit board, said
set of memory elements having a total of at least n data lines; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements
where in said electrical connector includes a full width data path such
that one of said single in-line memory modules can increase a main memory
in said computer system.
23. A memory structure for a computer system comprising:
an integrated video and data memory bus with n data lines; and
at least one single in-line memory module having:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said printed circuit board; and
a second set of memory elements arranged on said printed circuit board,
said first and second set of memory elements configured for integrated
data and video storage and having a total of at least n data lines
comprising a full width data path; a set of control signals in said
electrical connector electrically coupled to said first set of memory
elements and said second set of memory elements.
24. A memory structure for a computer system comprising:
an integrated video and data memory bus; and
at least one single in-line memory module having:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board;
a first set of memory elements arranged on said printed circuit board and
configured for integrated data and video storage; and
a driver circuit mounted on said printed circuit board, said driver circuit
coupled to a set of control signals in said electrical connector, said
driver circuit transmitting said controls signals to said first set of
memory elements;
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct.
25. A single in-line memory module for memory expansion in a computer
system having a memory bus, said single in-line memory module comprising
the elements of:
a printed circuit board, said printed circuit board having a first side and
a second side, said printed circuit board-having an electrical connector,
said electrical connector comprising a first set of electrical contacts on
said first side of said printed circuit board and a second set of
electrical contacts on said second side of said printed circuit board; and
a first set of memory elements arranged on said printed circuit board;
wherein said first set of electrical contacts and said second set of
electrical contacts are electrically distinct. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of computer systems and memory
hardware. More particularly, the present invention relates to modular
circuit boards which may be combined to form a memory structure within a
computer system.
3. Art Background
Single In-Line Memory Modules ("SIMMs") are compact circuit boards designed
to accommodate surface mount memory chips. SIMMs were developed to provide
compact and easy to manage modular memory components for user installation
in computer systems designed to accept such SIMMs. SIMMs generally are
easily inserted into a connector within the computer system, the SIMM
thereby deriving all necessary power, ground, and logic signals therefrom.
A SIMM typically comprises a multiplicity of random access memory ("RAM")
chips mounted to a printed circuit board. Depending on the user's needs,
the RAM memory chips may be dynamic RAM (DRAM), non volatile static RAM
(SRAM) or video RAM (VRAM). Because DRAM memories are larger and cheaper
than memory cells for SRAMs, DRAMs are widely used as the principal
building block for main memories in computer systems. SRAM and VRAM SIMMs
have more limited application for special purposes such as extremely fast
cache memories and video frame buffers, respectively. Because DRAMs form
the largest portion of a computer system memory, it is therefore desirable
that memory modules flexibly accommodate the computation needs of a user
as the users' requirements change over time. Moreover, it is desirable
that the SIMM modules may be added to the computer system with a minimum
user difficulty, specifically in terms of configuration of a SIMM within a
particular memory structure. In the past, SIMMs have generally been
designed to provide memory increments of one or more megabytes (MB), but
where the memory addition comprises only a portion of the full data path
used in the computer system. A leading example of the prior art
organization and structure is that disclosed in U.S. Pat/ No. 4,656,605,
issued Apr. 7, 1987 to Clayton. Clayton discloses a compact modular memory
circuit board to which are mounted nine memory chips which are arranged to
provide memory increments in eight bit (one byte) data widths, plus parity
bits. Thus, because most computer systems use data paths of 32, 64 or more
bits, the SIMM constructed according to Clayton cannot provide a memory
increment for the entire data path. Instead the user must obtain and
install multiple SIMMs, in combination with performing any additional
configuration requirements necessary to make the separate SIMMs modules
function as a single memory unit, such as setting base addresses for the
SIMM modules installed.
As a result, a user seeking to increase his usable main memory by adding
SIMMs constructed according to the prior art, typically must insert
multiple SIMMs to achieve a memory expansion for the entire data path of
his computer. The foregoing is a consequence of typical prior art SIMM
architecture, wherein the SIMM is arranged around DRAM parts which
comprise one byte wide memory increments. Thus in a data path having a
width of 32 bits, there being eight bits per byte, a 1 megabyte expansion
of main memory using SIMMs constructed according to the prior art would
require four SIMM modules each of one megabyte capacity in order to obtain
a full data path expansion of one megabyte.
As will be described in more detail in the following detailed description,
the present invention provides, among other attributes, facility for
providing memory expansion in full data pa | | |
