Solid state disk drive emulation

• US 5,131,089 A
• Filed: 09/28/1989
• Issued: 07/14/1992
• Est. Priority Date: 06/12/1989
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Grid Systems Corporation
• Inventors: Cole, James F.
• Primary Examiner(s): Fleming, Michael R.
• Assistant Examiner(s): CHUN, DEBRA
• Application Number:
  US07/413,803
• Time in Patent Office: 1,020 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 703/24
• CPC Class Codes: G06F 13/00 Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units interface circuits for specific input/output devices G06F3/00 ; multiprogram control therefor G06F9/46; multiprocessor systems G06F15/16
• 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
• CPC Class Codes: G06F 9/463 Program control block organisation

Abstract

A system for causing a computer solid state memory to emulate a magnetic disk mounted in a disk drive. In the preferred embodiment, the system includes two removable RAM cards and two ROM'"'"'s. Program instructions encoded in firmware in the system BIOS translate disk service requests from software running on the computer into appropriate commands and addresses on the RAM cards or on the ROM. The system permits software written for use with floppy disks to be used with solid state memory devices such as RAM cards or ROM without modification of the software.

Claims

1. A disk drive emulation system for a computer comprising:

solid state memory having an on state and an off state and specifiable data addresses; and

an input/output system for interfacing between computer hardware and computer software, the input/output system comprising emulation means for causing the solid state memory to emulate a magnetic disk mounted in a disk drive, the emulation means comprising;

means for receiving a software disk service request;

means responsive to receipt of a software disk service request for blocking receipt of a subsequent request until the received request has been completed;

firmware means for determining the type of software disk service request;

firmware means responsive to the determining means for reading from the solid state memory in response to a read request, the means for reading including means for translating a magnetic disk address into a solid state memory address, means for seeking to a specified address, and means for transferring data from the solid state memory to the software requesting service;

firmware means responsive to the determining means for writing to the solid state memory in response to a write request, the means for writing including means for translating a magnetic disk address into a solid state memory address, means for seeking to a specified address, and means for transferring data from the software making the request to the solid state memory; and

means for preventing operation of said reading means and said writing means after completion of the received request until receipt of a subsequent request by said receiving means, whereby software written for use with magnetic disk memory may be used in a computer having solid state memory in place of magnetic disk memory.

2. The system of claim 1 wherein the emulation means further comprises firmware means for turning the solid state memory to the off state in response to a disk reset request.

3. The system of claim 1 wherein the emulation means further comprises firmware means for formatting the solid state memory in response to a format disk request from the software, the means for formatting including means for translating a magnetic disk address into a solid state memory address, means for seeking to a specified address, and means for writing a format character to a specified address.

4. The system of claim 1 wherein the emulation means further comprises firmware means for reading disk parameters in response to a software request.

5. The system of claim 1 wherein each means for translating comprises means for dividing the solid state memory into virtual disk cylinders, heads and sectors, the solid state memory having undesignated memory space if the solid state memory is not an integral multiple 18 the cylinder size.

6. The system of claim 1 wherein the emulation means further comprises firmware means for determining whether a software service request is for data on an external memory or data on the solid state memory.

7. The system of claim 1 wherein the means for transferring comprises a memory interface means in communication with the solid state memory, the interface means including a buffer and control ports.