Three port random access memory

• US 4,891,794 A
• Filed: 06/20/1988
• Issued: 01/02/1990
• Est. Priority Date: 06/20/1988
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Cloud, Eugene H., Mailloux, Jeffrey S., Hush, Glen E.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Bowler, Alyssa H.
• Application Number:
  US07/208,676
• Time in Patent Office: 561 Days
• Field of Search: 365/189, 365/230, 365/239, 365/240, 365/230.03, 365/230.05, 365/230.09, 365/189.04, 365/221
• US Class Current: 365/189.04
• CPC Class Codes: G11C 7/1075 for multiport memories each having random access ports and serial ports, e.g. video RAM

Abstract

A three port memory device has two serial ports and a random access memory port. The random access memory port is addressed to a random access memory in a conventional manner, using RAS and CAS address signals. Data may also be supplied and retrieved through two serial ports to a pair of serial access memories for transfer between the serial ports and the random access memory. This configuration permits formatted data to be simultaneously assessed through the two serial ports, while the random access memory port is being accessed.

Claims

1. Solid state memory device capable of receiving and transmitting data in a serial format and permitting random access to the data, characterized by:

(a) a random access memory array containing a plurality of data bits;

(b) a plurality of serial access memories;

(c) transfer circuitry including a plurality of transfer gates communicating with the random access memory array, the transfer circuitry communicating between the transfer gates and the serial access memories in order to transfer data between the random access memory and the serial access memories;

(d) the transfer circuitry transferring said data selectively to any one of said plurality of serial access memories;

(e) the transfer circuitry including a transfer control circuit controlling with which serial access memory said transfer of data is performed; and

(f) a serial address connection for at least two of the serial access memories.

2. Solid state memory device as described in claim 1, further characterized by:

the random access memory array being addressable by external read commands and by external write commands.

3. Solid state memory device as described in claim 2, further characterized by:

the serial address memories being static or dynamic memory circuits which are each addressed in at least one static sequence.

4. Solid state memory device as described in claim 3, further characterized by:

the random access memory array being addressable by RAS and CAS address commands.

5. Solid state memory device as described in claim 4, further characterized by:

(a) the memory device being incorporated onto a single portion of a semiconductor wafer; and

(b) the random access memory array being a dynamic random access memory array.

6. Solid state memory device as described in claim 2, further characterized by:

the transfer circuitry communicating between the transfer gates and the serial access memories in order to transfer data between the random access memory and any one of a plurality of the serial access memories;

7. Solid state memory device as described in claim 6, further characterized by:

each serial access memory including a plurality of multiple bit memories, each of which plurality is separately addressable.

8. Solid state memory device as described in claim 2, further characterized by:

the serial address memories being dynamic memory circuits which are each addressed in at least one sequence.

9. Solid state memory device as described in claim 1, further characterized by:

each serial access memory including a plurality of multiple bit memories, each of which plurality is separately addressable.

10. Solid state memory device as described in claim 1, further characterized by:

(a) the memory device being incorporated onto a single portion of a semiconductor wafer; and

(b) the random access memory array being a dynamic random access memory array.

11. Solid state memory device as described in claim 1, further characterized by:

(a) the memory device being incorporated onto a single portion of a semiconductor wafer; and

(b) the random access memory array being a static random access memory array.

12. Solid state memory device as described in claim 1, further characterized by:

the serial address memories each being registers having like number of bits;

the serial address memories each having independent enable inputs;

the serial address memories each being responsive to a directional control signal; and

the transfer of said data being accomplished when a transfer enable signal and the directional control signal are applied to the serial address memory.

13. Solid state memory device capable of receiving and transmitting data in a serial format and permitting random access to the data, characterized by:

(a) a random access memory array containing a plurality of data bits,

(b) a plurality of serial access memories;

(c) the random access memory array being addressable by external read commands and by external write commands;

(d) the serial address memories being static memory circuits which are each addressed in at least one static sequence;

(e) a plurality of transfer gates communicating with the random access memory array and the serial access memories in order to transfer data between the random access memory and one of the serial access memories;

(f) the plurality of transfer gates transferring said data selectively to any one of said plurality of serial access memories; and

(g) a serial address connection for at least two of the serial access memories.

14. Solid state memory device as described in claim 13, further characterized by:

the random access memory array being addressable by RAS and CAS address commands.

15. Solid state memory device as described in claim 14, further characterized by:

(a) the memory device being incorporated onto a single portion of a semiconductor wafer; and

(b) the random access memory array being a dynamic random access memory array.

16. Solid state memory device as described in claim 13, further characterized by:

the serial address memories being dynamic memory circuits which are each addressed in at least one sequence.

17. Solid state memory device as described in claim 13, further characterized by:

(a) the memory device being incorporated onto a single portion of a semiconductor wafer; and

(b) the random access memory array being a dynamic random access memory array.

18. Solid state memory device as described in claim 13, further characterized by:

(a) the memory device being incorporated onto a single portion of a semiconductor wafer; and

(b) the random access memory array being a static random access memory array.

19. Solid state memory device as described in claim 13, further characterized by:

each serial access memory including a plurality of multiple bit memories, each of which plurality is separately addressable.

20. Solid state memory device as described in claim 13, further characterized by:

the serial address memories each being registers having like number of bits;

the serial address memories each having independent enable inputs;

the serial address memories each being responsive to a directional control signal; and

the transfer of said data being accomplished when a transfer enable signal and the directional control signal are applied to the serial address memory.