INTEGRATED CIRCUIT AND METHOD OF AUTOMATICALLY SELECTING AN INTERNAL OR AN EXTERNAL NON-VOLATILE MEMORY AS A SOURCE OF PROGRAM CODE RESPONSIVE TO PRESENCE OR ABSENCE OF THE EXTERNAL NON-VOLATILE MEMORY

• US 6,912,101 B2
• Filed: 03/27/2001
• Issued: 06/28/2005
• Est. Priority Date: 03/28/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Takase, Yasuhiro, Murakami, Masayuki, Sakai, Tatsuya
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): WONG, KIN C
• Application Number:
  US09/818,485
• Publication Number:
  US 20010040750A1
• Time in Patent Office: 1,554 Days
• Field of Search: 360/69, 360/77.04, 711/105, 711/15, 711102-103, 713/1, 713/2, 713/340, 365/189.03, 365/230.8, 710/266, 700/297, 257/324, 327/78
• US Class Current: 360/69
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/0676 Magnetic disk device
• CPC Class Codes: G06F 9/4403 Processor initialisation

Abstract

The present invention is a semiconductor device that includes a DRAM and an internal mask ROM that are implemented on a single integrated circuit substrate. The semiconductor further includes a terminal coupled to an external ROM and a selector for choosing an external ROM or an internal mask ROM for program code loading. If an external ROM is coupled to the aforementioned terminal, the external ROM is given precedence for use in the loading of the aforementioned program code. The control method of the present invention pertains to a semiconductor device including a DRAM, an internal mask ROM, a terminal coupled to an external ROM, a selector for choosing the first path led from the internal mask ROM or the second path led from the terminal, and a coupling determiner deciding whether or not the terminal is coupled to the external ROM. The control method includes the steps of: (a) deciding whether or not the terminal is coupled to the external ROM; (b) selecting a first path when a terminal is not coupled to the external ROM or a second path when the terminal is coupled to the external ROM; and (c) loading a program code from either the internal mask ROM or the external ROM.

Claims

1. A semiconductor device, comprising:

a single integrated circuit substrate including;

a volatile memory;

an internal non-volatile memory

a terminal for optionally coupling an external non-volatile memory device to said semiconductor device; and

a selector system coupled to said internal non-volatile memory and said terminal, wherein said selector system selects a single source from which to load a program code into said volatile memory from among said external non-volatile memory and said internal non-volatile memory device based upon whether or not said external non-volatile memory device is coupled to said terminal, said selector system including;

a coupling detector for detecting whether or not said external non-volatile memory device is coupled to said terminal; and

a source selector, coupled to said coupling detector, for selecting said internal non-volatile memory as said source in response to said coupling detector detecting that said external non-volatile memory device is not coupled to said terminal and for selecting said external non-volatile memory device as said source in response to said coupling detector detecting that said external non-volatile memory device is coupled to said terminal.

2. The semiconductor device according to claim 1, wherein said coupling detector further comprises:

a comparator that outputs a signal indicative of absence of said external non-volatile memory device responsive to said terminal having a predetermined input value.

3. The semiconductor device according to claim 2, wherein said predetermined input value represents a reference voltage.

4. The semiconductor device according to claim 1, and further comprising a memory controller coupled to said selector system that issues a read command to said selector system to load said program code.

5. The semiconductor device according to claim 1, wherein said volatile memory comprises a dynamic random access memory (DRAM).

6. The semiconductor device according to claim 1, wherein said semiconductor device is a hard disk controller and further comprises:

a drive interface that couples said semiconductor device to a hard disk drive and relays data; and

a host interface that couples said semiconductor device to a host computer and relays data.

7. The semiconductor device according to claim 1, wherein said internal non-volatile memory comprises a Read Only Memory (ROM).

8. The semiconductor device according to claim 1, and further comprising:

a serial-to-parallel converter, coupled between said selector system and said volatile memory, that converts said program code from serial to parallel format prior to storage of said program code into said volatile memory.

9. A method for controlling a semiconductor device that includes an internal volatile memory, an internal non-volatile memory, and a terminal for optionally coupling an external non-volatile memory device to the semiconductor device, said method comprising:

detecting whether or not an external non-volatile memory device is coupled to said terminal;

in response to said detecting, selecting a single one of said internal non-volatile memory and the external non-volatile memory device as a source of a program code, wherein said internal non-volatile memory is selected as the source if the external non-volatile memory device is not coupled to said terminal and the external non-volatile memory device is selected as the source if the external non-volatile storage device is coupled to said terminal; and

loading a program code from said selected source into the internal volatile memory.

10. The method for controlling a semiconductor device according to claim 9, wherein said step of detecting comprises:

comparing an input value present at said terminal with a predetermined input value.

11. The method for controlling a semiconductor device according to claim 10, wherein said predetermined input value represents a reference voltage.

12. The method for controlling a semiconductor device according to claim 9, wherein said loading comprises serially transmitting said program code from said selected source to a serial/parallel converter within said semiconductor device;

and

converting said program code from serial to parallel format at said serial/parallel converter; and

transmitting said program code in parallel format from said serial/parallel converter to said volatile memory.

13. The method of controlling a semiconductor device according to claim 9, wherein said loading comprises loading said program code in response to a read command by a memory controller.

14. The method for controlling a semiconductor device according to claim 9, and further comprising controlling operation of a disk drive responsive to said program code.

15. A hard disk drive comprising:

a hard disk recording medium;

a medium driver;

a magnetic head located at the tip of an arm; and

a controller that controls driving of said hard disk recording medium by said medium driver, movement of said arm, and transfer of data to and from said hard disk recording medium via said magnetic head according to a program code, wherein said controller comprises a single integrated circuit substrate including;

a volatile memory;

an internal non-volatile memory;

a terminal for optionally coupling an external non-volatile memory device to said semiconductor device; and

a selector system coupled to said internal non-volatile memory and said terminal, wherein said selector system selects a single source from which to load a program code into said volatile memory from among said external non-volatile memory and said internal non-volatile memory device based upon whether or not said external non-volatile memory device is coupled to said terminal, said selector system including;

a coupling detector for detecting whether or not said external non-volatile memory device is coupled to said terminal; and

a source selector, coupled to said coupling detector, for selecting said internal non-volatile memory as said source in response to said coupling detector detecting that said external non-volatile memory device is not coupled to said terminal and for selecting said external non-volatile memory device as said source in response to said coupling detector detecting that said external non-volatile memory device is coupled to said terminal.