Computer including optical interconnect, memory unit, and method of assembling a computer

Claims

What is claimed is:

1. A computer comprising:

a housing;

a circuit board supported in the housing;

a plurality of slot connectors supported on the circuit board;

a first card configured for sliding receipt in one of the slot connectors;

a processor mounted on the first card;

a second card configured for sliding receipt in one of the slot connectors;

a memory mounted on the second card; and

a flexible optical interconnect coupling the first card to the second card, the processor being configured to communicate with the memory via the optical interconnect whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

2. A computer in accordance with claim 1 wherein the optical interconnect comprises a fiber optic cable.

3. A computer in accordance with claim 1 wherein the optical interconnect comprises an optical connector on the first card configured to convert between electrical signals and optical signals, and wherein the computer further includes circuit traces on the first card coupling the optical connector to the processor.

4. A computer in accordance with claim 1 wherein the optical interconnect comprises an optical connector on the second card configured to convert between electrical signals and optical signals, and wherein the computer further includes circuit traces on the second card coupling the optical connector to the memory.

5. A computer in accordance with claim 1 wherein the optical interconnect comprises a first optical connector, on the first card, configured to convert between electrical signals and optical signals, wherein the computer further includes circuit traces on the first card coupling the first optical connector to the processor, wherein the optical interconnect further comprises an optical connector, on the second card, configured to convert between electrical signals and optical signals, the computer further including circuit traces on the second card coupling the second optical connector to the memory.

6. A computer in accordance with claim 1 wherein the memory comprises a DRAM.

7. A computer in accordance with claim 1 wherein the memory comprises a synchronous link type DRAM.

8. A computer comprising:

a housing;

a motherboard supported in the housing;

a slot connector supported on the motherboard;

a processor supported by the motherboard;

a card configured for sliding receipt in one of the slot connectors;

a memory mounted on the card; and

a flexible optical interconnect coupling the card to the motherboard, the processor being configured to communicate with the memory via the optical interconnects whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

9. A computer in accordance with claim 8 wherein the processor is hard wired to the motherboard.

10. A computer in accordance with claim 8 and further comprising a ZIF connector mounted to the motherboard, and wherein the processor is removably received in the ZIF connector.

11. A computer in accordance with claim 8 wherein the optical interconnect comprises an optical connector on the card configured to convert between electrical signals and optical signals, and an optical connector on the motherboard configured to convert between electrical signals and optical signals.

12. A computer in accordance with claim 8 wherein the memory comprises a DRAM.

13. A computer in accordance with claim 8 wherein the memory comprises a synchronous link type DRAM.

14. A computer comprising:

a housing;

a circuit board supported in the housing;

a plurality of slot connectors supported on the circuit board;

a first card having an edge connector configured for sliding receipt in a first one of the slot connectors;

a processor supported by the first card;

a second card having an edge connector configured for sliding receipt in a second one of the slot connectors;

a synchronous link DRAM memory supported by the second card;

a power supply in the housing;

circuit traces coupling the power supply to the processor via the first slot connector;

circuit traces coupling the power supply to the memory via the second slot connector; and

a flexible optical interconnect coupling the processor to the memory for data communications, wherein the slot connectors and edge connectors are used for supplying power to the processor and memory but not for data communication between the processor and the memory whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

15. A computer in accordance with claim 14 wherein the synchronous link DRAM memory is defined by an integrated circuit, and further comprising a plurality of additional integrated circuits supported by the second card, the computer further including multiple respective circuit traces coupling the integrated circuits supported by the second card to the edge connector of the second circuit card, whereby because the edge connector is not used for data communication, additional traces at the edge connector can be used for power.

16. A computer in accordance with claim 14 and further comprising a zero insertion force (ZIF) connector mounted to the first card, and wherein the processor is removably received in the zero insertion force connector.

17. A computer in accordance with claim 14 wherein the processor is surface mounted on the first card.

18. A computer comprising:

a housing;

a circuit board supported in the housing;

a plurality of slot connectors supported on the circuit board;

a first card having an edge connector configured for sliding receipt in a first one of the slot connectors;

a processor supported by the first card;

a second card having an edge connector configured for sliding receipt in a second one of the slot connectors;

a, synchronous link DRAM memory supported by the second card;

a power supply in the housing;

conductors coupling the power supply to the processor via the first slot connector, the conductors including circuit traces on the first card extending from the edge connector of the first card toward the processor;

conductors coupling the power supply to the memory via the second slot connector, the conductors including circuit traces on the second card extending from the edge connector of the second card toward the memory; and

a flexible optical interconnect coupling the processor to the memory for data communications, the optical interconnect being within the housing whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

19. A computer in accordance with claim 18 and further comprising a third card having an edge connector configured for sliding receipt in a third one of the slot connectors, a co-processor supported by the third card, and an optical interconnect coupling the co-processor to the processor.

20. A computer in accordance with claim 19 and further comprising conductors coupling the power supply to the co-processor via the third slot connector, the conductors including circuit traces on the third card extending from the edge connector of the third card toward the co-processor.

21. A computer in accordance with claim 19 wherein the co-processor is a math co-processor.

22. A computer in accordance with claim 19 and further including an electronic device in the housing capable of generating electromagnetic interference, and wherein the optical interconnect shields communications between the processor and the memory from the electromagnetic interference.

23. A method of assembling a computer, the method comprising:

supporting a circuit board in a housing;

supporting a plurality of slot connectors on the circuit board;

mounting a processor on a first card;

inserting the first card into a first one of the slot connectors;

mounting a memory on a second card;

inserting the second card into a second one of the slot connectors; and

flexibly optically coupling the first card to the second card for optical communications between the processor and the memory whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

24. A method of assembling a computer in accordance with claim 23 wherein optically coupling the first card to the second card comprises using a fiber optic cable.

25. A method of assembling a computer in accordance with claim 23 wherein optically coupling the first card to the second card comprises supporting an optical connector on the first card to convert between electrical signals and optical signals, and forming circuit traces on the first card to couple the optical connector to the processor.

26. A method of assembling a computer in accordance with claim 23 wherein optically coupling the first card to the second card comprises supporting an optical connector on the second card to convert between electrical signals and optical signals, and forming circuit traces on the second card to couple the optical connector to the memory.

27. A method of assembling a computer in accordance with claim 23 wherein optically coupling the first card to the second card comprises supporting an optical connector on the first card to convert between electrical signals and optical signals, forming circuit traces on the first card to couple the optical connector to the processor, supporting an optical connector on the second card to convert between electrical signals and optical signals, and forming circuit traces on the second card to couple the optical connector to the memory.

28. A method of assembling a computer in accordance with claim 23 wherein mounting the memory comprises mounting a DRAM on the first card.

29. A method of assembling a computer in accordance with claim 23 wherein mounting the memory comprises mounting a synchronous link type DRAM on the first card.

30. A method of assembling a computer, the method comprising:

supporting a circuit board in a housing;

supporting a plurality of slot connectors on the circuit board;

supporting a processor on a first card having an edge connector;

inserting the edge connector of the first card in a first one of the slot connectors;

supporting a synchronous link DRAM memory on a second card having an edge connector;

inserting the edge connector of the second card in a second one of the, slot connectors;

supporting a power supply in the housing;

coupling the power supply to the processor via the first slot connector and circuit traces on the first card;

coupling the power supply to the memory via the second slot connector and circuit traces on the second card; and

flexibly optically coupling the processor to the memory for data communications, wherein the slot connectors and edge connectors are used for supplying power to the processor and memory but not for data communication between the processor and the memory whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

31. A method of assembling a computer in accordance with claim 30 wherein supporting the synchronous link DRAM memory on the second card comprises supporting an integrated circuit on the second card, the method further comprising supporting a plurality of additional integrated circuits on the second card, and coupling the integrated circuits supported by the second card to the edge connector of the second circuit card with circuit traces, whereby because the edge connector is not used for data communication, additional traces at the edge connector can be used for power.

32. A method of assembling a computer in accordance with claim 30 and further comprising mounting a zero insertion force (ZIP) connector to the first card, and removably mounting the processor in the zero insertion force connector.

33. A method of assembling a computer in accordance with claim 30 and further comprising surface mounting the processor on the first card.

34. A method of assembling a computer, the method comprising:

supporting a circuit board in a housing;

supporting a plurality of slot connectors on the circuit board;

supporting a processor on a first card having an edge connector;

inserting the edge connector of the first card into a first one of the slot connectors to support the first card from the circuit board;

providing a second card having an edge connector configured for sliding receipt in a second one of the slot connectors;

supporting a synchronous link DRAM memory on a second card having an edge connector;

inserting the edge connector of the second card into a second one of the slot connectors to support the second card from the circuit board;

supporting a power supply in the housing;

coupling the power supply to the processor via the first slot connector, the coupling including using circuit traces on the first card extending from the edge connector of the first card toward the processor; coupling the power supply to the memory via the second slot connector, the coupling including using circuit traces on the second card extending from the edge connector of the second card toward the memory; and

optically coupling the processor to the memory for data communications using a flexible optical interconnect within the housing whereby the flexible optical interconnect does not pass through the slot connectors so that interference that could otherwise be caused by signals to and from the processor is impeded.

35. A method of assembling a computer in accordance with claim 34 and further comprising supporting a co-processor on a third card having an edge connector, and optically coupling the co-processor to the processor.

36. A method of assembling a computer in accordance with claim 35 and further comprising coupling the power supply to the co-processor via the third slot connector, the coupling comprising using circuit traces on the third card extending from the edge connector of the third card toward the co-processor.

37. A method of assembling a computer in accordance with claim 35 wherein supporting a co-processor comprises supporting a math co-processor on the third card.

TECHNICAL FIELD

The invention relates to memory systems. The invention also relates to fiber optic systems.

BACKGROUND OF THE INVENTION

Processor speeds of computers continue to increase. Devices with which the processor communicates often do not operate at such high speeds. For example, static random access memories (SRAMs) often operate at almost as high a speed as the processor, but dynamic random access memories (DRAMs) operate at a slower speed. Dynamic random access memories possess advantages to static random access memories. For example, static random access memories require more space than dynamic random access memories.

Rambus Inc. of Mountain View, Calif. has technology that allows DRAMs and controllers or processors to transfer data at a high frequency, such as 600 megabytes per second and above over a Rambus Channel, a narrow byte-wide data bus. Attention is directed to the following patents assigned to Rambus, Inc., which are incorporated herein by reference: U.S. Pat. No. 5,680,361 to Ware et al.; Pat. No. 5,663,661 to Dillon et al.; Pat. No. 5,537,573 to Ware et al.; Pat. No. 5,499,385 to Farmwald et al.; Pat. No. 5,499,355 to Krishnamohan et al.; Pat. No. 5,485,490 to Leung et al.; Pat. No. 5,446,696 to Ware et al.; Pat. No. 5,432,823 to Gasbarro et al.; Pat. No. 5,430,676 to Ware et al.; Pat. No. 5,390,308 to Ware et al.; Pat. No. 5,355,391 to Horowitz et al.

An alternative to Rambus has been developed by memory chip makers. The synchronous link DRAM (SLDRAM) is an alternative to double-data-rate (DDR) and Direct Rambus DRAM.

The SLDRAM is known in the art. The SLDRAM, formerly known as SynchLink, is designed for computer main memory in mobile, desktop, workstation, and server systems. It is designed to reduce a speed bottleneck in accessing memory from a processor. The SLDRAM project attempts to solve a memory system problem that will become more acute in newer systems. DRAM memory chips do not have enough bandwidth for getting the data on or off the memory chips. To solve this problem, manufacturers have been using many chips in a wide array to get the speed up to what their system needs. However, new DRAM chips will have increasingly higher capacities, so that there will be so much DRAM capacity in the wide array of chips needed for getting the speed, that the price of the DRAM capacity raises the price of the computer. For lower price or entry-level computers and workstations, this price may be excessive. Unnecessarily large memory would exist in base configurations. Although new software uses more memory, that memory usage is not growing as fast as DRAM density, and this mismatch may result in overly expensive computers.

SLDRAM addresses this problem by using a new architecture for communicating with the DRAMs, with two highly optimized buses. This allows increasing the DRAM bandwidth significantly. SLDRAM adds pipelined transfer protocol for increased advantage of bandwidth. Attention is directed to the SLDRAM White Paper of Aug. 29, 1997, which describes SLDRAM in greater detail.

SLDRAMs are synchronously linked to processors. To provide high speed access to the memories, as processor speed increases, lengths of circuit traces should decrease.

It is known to use optical waveguides as interconnects from integrated circuit to integrated circuit. See, for example, U.S. Pat. No. 5,119,451, which is incorporated herein by reference. Various R&D efforts have taken place in an attempt to develop optical interconnect technology for short-haul data communications applications such as for communications between boards, backplanes, and intra-boxes. See, for example, "Lighting the Way in Computer Design," IEEE Circuits & Devices, January 1998.

SUMMARY OF THE INVENTION

The invention provides a computer. The computer includes a housing, and a circuit board supported in the housing. A plurality of slot connectors are supported on the circuit board. A first card is configured for sliding receipt in one of the slot connectors. A processor is mounted on the first card. A second card is configured for sliding receipt in one of the slot connectors. A memory is mounted on the second card. An optical interconnect couples the first card to the second card. The processor is configured to communicate with the memory via the optical interconnect.

In one aspect of the invention, the optical interconnect comprises a fiber optic cable.

In another aspect of the invention, the optical interconnect comprises an optical connector on the first card configured to convert between electrical signals and optical signals, and the computer further includes circuit traces on the first card coupling the. optical connector to the processor.

In another aspect of the invention, the optical interconnect comprises an optical connector on the second card configured to convert between electrical signals and optical signals, and the computer further includes circuit traces on the second card coupling the optical connector to the memory.

In another aspect of the invention, the memory comprises a DRAM. In another aspect of the invention, the memory comprises a synchronous link type DRAM.

Another aspect of the invention provides a memory unit configured to be slidably received in a slot connector on a circuit board. The memory unit comprises a card having a connector configured to mate with the slot connector. A synchronous link DRAM memory is supported by the card. Circuit traces on the card extend from the connector of the card toward the memory. The circuit traces are configured to couple the memory to a power supply via the slot connector. An optical interface is supported by the card and coupled to the memory. The optical interface is configured to convert electrical signal to optical signals, for optical data transmission to and from the memory.

Another aspect of the invention provides a method of assembling a computer. The method comprises supporting a circuit board in a housing. A plurality of slot connectors are supported on the circuit board. A processor is mounted on a first card. The first card is inserted into a first one of the slot connectors. A memory is mounted on a second card. The second card is inserted into a second one of the slot connectors. The first card is optically connected to the second card for optical communications between the processor and the memory.

By reducing the circuit trace path on a memory card, communication speed is increased. Inexpensive circuit cards can be used instead of Teflon substrate or low dielectric cards. Memory integrated circuits can be mounted on cards prior to burn-in because the circuit cards are inexpensive. This is less expensive than burning-in memory integrated circuits before they are mounted on circuit cards. Unsophisticated users can add memory and integrated circuits easily. They can insert a SIMM module or card, attach one end of the fiber optic cable to an optical interconnect on the SIMM module, and attach the other end of the fiber optic cable to the optical interface on the processor card, and the installation is complete. Electromagnetic interference caused by power supply transformers or disk drives is less of a concern because the optical communications are immune to such interference.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the following accompanying drawings.

FIG. 1 is a perspective view of a computer embodying the invention.

FIG. 2 is a perspective view of a computer, illustrating removal of a card bearing a processor.

FIG. 3 is a perspective view of a computer, illustrating insertion of a card bearing a processor.

FIG. 4 is a perspective view of a computer, illustrating a card bearing a processor in accordance with an alternative embodiment of the invention.

FIG. 5 is a perspective view of a computer in accordance with an alternative embodiment of the invention.

FIG. 6 is a perspective view of a computer in accordance with another alternative embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws "to promote the progress of science and useful arts" (Article 1, Section 8).

FIG. 1 illustrates a computer 10 embodying the invention. The computer comprises a housing 12, and a circuit board 14 supported in the housing 12. The computer 10 further includes a plurality of slot connectors 16, 18, 20, 22 supported on the circuit board, and a first card 24 configured for sliding receipt in one of the slot connectors (e.g., the slot connector 16).

The first card 24 has an edge connector 26 configured for sliding receipt in the slot connector 16. The computer 10 further includes a processor 28 mounted on the first card 24.

The computer 10 further includes a second card 30 configured for sliding receipt in one of the slot connectors (e.g., the slot connector 18). The second card 30 has an edge connector 32 configured for sliding receipt in the slot connector 18.

Because the processor 28 is mounted on a removable card, it can be more easily upgraded. Instead of having to insert a processor 28 in a socket after aligning pins, th