Flash memory system

• US 5,640,349 A
• Filed: 01/18/1996
• Issued: 06/17/1997
• Est. Priority Date: 08/31/1994
• Status: Expired due to Term

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Kakinuma, Yuji, Karibe, Hiroshi, Terasaki, Yukio
• Primary Examiner(s): Nguyen, Viet Q.
• Application Number:
  US08/588,332
• Time in Patent Office: 516 Days
• Field of Search: 365/185.01, 365/185.11, 365/230.01, 365/218, 365/425
• US Class Current: 365/185.33
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system

Abstract

A flash memories (20, 21) are coupled with a host computer (1) through a flash memory controller (2) which has a pair of data buses (27, 28), and a pair of buffer memories (22, 23). Each of said data buses is coupled with a related flash memory, and a related buffer memory, which is coupled with said host computer. Said data buses (22, 23) are controlled to operate simultaneously so that said flash memories are accessed simultaneously in parallel form. A data in said host computer is transferred to said flash memories through said buffer memories and said data buses, and vice versa. All the elements (20, 21, 2) are mounted on a plastics card (100) called a flash memory card, which is coupled with a host computer through a connector. Because of use of a plurality of buses operating in parallel form, the transfer time of data between a host computer and a flash memory card is shortened.

Claims

1. A flash memory system coupled with a host computer comprising:

a plurality of flash memory chips, and

a flash memory controller for controlling transfer of data between said memory chips and said host computer,

said flash memory controller comprising

a plurality of data buses each coupled with a related flash memory chip for transferring data to/from said flash memory chips,

an address buffer coupled with said data buses through gates, to supply address information to said flash memory chips through said data buses,

a plurality of buffer memories each coupled with a related data bus and said host computer for storing data to be transferred to/from a flash memory chip temporarily,

a flash memory sequencer for controlling said data buses and said buffer memories simultaneously so that a plurality of flash memory chips are accessed simultaneously in parallel form,

a plurality of comparators for comparing status information supplied by a related flash memory chip with predetermined reference information, and

an AND circuit for providing logical AND operation for outputs of said comparators so that said AND circuit provides a positive output signal only when all the flash memory chips operate correctly in a previous operation.

2. A flash memory system according to claim 1, wherein a number of said data buses, said flash memory chips, said buffer memories, and said comparators is two.

3. A flash memory system according to claim 1, wherein data in each of said data bus is in parallel form.

4. A flash memory system according to claim 1, wherein each of said data bus transfers not only data, but also address and command to a flash memory chip.

5. A flash memory system according to claim 1, said flash memory sequencer comprises a counter, a sequencer RAM which stores instructions at an address which is indicated by said counter, an instruction decoder coupled with said sequencer RAM for decoding a instruction so that a decoded micro order is sent to a flash memory chip through said data bus, and a decision circuit which adjusts content of said counter depending upon an output of said AND circuit.

6. A flash memory system according to claim 1, wherein each of said flash memory chips has 8 bits in each address.

7. A flash memory system according to claim 1, further comprising a support card on which said flash memory chips, and said flash memory controller are mounted, and said support card has a connector which is connected to a host computer.

8. A flash memory controller for controlling transfer of data between flash memory chips which are coupled with said controller and a host computer, comprising:

a plurality of data buses each coupled with a related flash memory chip for transferring data to/from said flash memory chips,

a plurality of buffer memories each coupled with a related data bus and said host computer for storing data to be transferred to/from a flash memory chip temporarily, and

a flash memory control for controlling said data buses and said buffer memories simultaneously so that a plurality of flash memory chips are accessed simultaneously, including a plurality of comparators for comparing status information supplied by a related flash memory chip with predetermined reference information, and an AND circuit for providing logical AND operation for outputs of said comparators so that said AND circuit provides a positive output signal only when all the flash memory chips operate correctly in a previous operation.