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US 5,473,775 AGranted
Personal computer using flash memory as BIOS-ROM
AssigneeKabushiki Kaisha Toshiba
InventorsMakoto Sakai, Makoto Arai
Life of this patent
Estimating the term…
Abstract
A personal computer uses a flash memory equipped with a main block storing a boot block and a basic input/output system as its BIOS-ROM. An address translation circuit, after power-on reset, supplies addresses output by a central processing unit to the BIOS-ROM as they are to thereby allow access to the boot block storing a far jump instruction. After system startup, the address translation circuit inverts a predetermined bit of each address output by the CPU to thereby allowing access to the BIOS. To refresh the contents of the BIOS-ROM, the CPU transfers a BIOS stored on a floppy disk to the main block of the BIOS-ROM.
Claims24
A personal computer comprising:
- a BIOS-ROM comprising a flash memory having a first storage area which reserves a read-only boot area and a second storage area which stores a first basic input/output system, said first and second storage areas being distinguished from each other by a predetermined bit of address data, a far jump instruction being stored in a predetermined location of said boot area;
- an external storage device for storing a second basic input/output system;
- data processing means for, immediately after power-on reset, outputting predetermined address data to access said boot area of said BIOS-ROM, thereby executing said far jump instruction and for, after system startup, outputting address data differing from said predetermined address data, wherein the address data output after system startup includes address data used to access said first storage area of said BIOS-ROM, thereby performing operations according to said first basic input/output system stored in said BIOS-ROM;
- address translating means, connected to said data processing means to receive the address data output from said data processing means after system startup, wherein said address data includes said predetermined bit of address data which distinguishes said first storage area and said second storage area, and for inverting a logical value of said predetermined bit and outputting the address data including the inverted bit to said BIOS-ROM;
- masking means connected to said data processing means for masking address data output from said data processing means which designates said second storage area, thereby preventing said BIOS-ROM from being accessed after system startup;
- instruction inputting means for inputting a transfer instruction to transfer said second basic input/output system from said external storage device to said BIOS-ROM;
- first determining means for determining, by virtue of the execution of said far jump instruction, whether or not said transfer instruction is input from said inputting means;
- second determining means for determining whether stored data of said BIOS-ROM is correct or not when said first determining means determines that said transfer instruction is not input from said inputting means;
- means for setting said address translating means and said masking means to an enabled state when said second determining means determines that the stored data of said BIOS-ROM is correct;
- and
- means for transferring said second basic input/output system from said external storage device to said BIOS-ROM to rewrite said first basic input/output system stored in said BIOS-ROM in a first case when said first determining means determines that said transfer instruction has been input from said inputting means and in a second case when said first determining means determines that no transfer instruction is input from said inputting means and said second determining means determines that the stored data of said BIOS-ROM is incorrect, wherein said second basic input/output system is automatically transferred from said external storage device to said BIOS-ROM in said second case.
8 more elements
A personal computer comprising:
- a BIOS-ROM comprising a flash memory having a first storage area which reserves a read-only boot area and a second storage area which stores a basic input/output system, said first and second storage areas being distinguished from each other by a predetermined bit of address data, a far jump instruction being stored in a predetermined location of said boot area;
- data processing means for, immediately after power-on reset, outputting predetermined address data to access said boot area of said BIOS-ROM, thereby executing said far jump instruction and for, after system startup, outputting address data differing from said predetermined address data, wherein the address data output after system startup includes address data used to access said first storage area of said BIOS-ROM, thereby performing operations according to said basic input/output system stored in said BIOS-ROM;
- and
- address translating means, connected to said data processing means to receive the address data output from said data processing means after system startup, wherein said address data includes said predetermined bit of address data which distinguishes said first storage area and said second storage area, and for inverting a logical value of said predetermined bit and outputting the address data including the inverted bit to said BIOS-ROM.
1 more element
A personal computer comprising:
- a BIOS-ROM comprising a flash memory having a first storage area which reserves a boot area and a second storage area which stores a basic input/output system, said first and second storage areas being distinguished from each other by a predetermined bit of address data;
- data processing means for, immediately after power-on reset, outputting predetermined address data to access said boot area of said BIOS-ROM and for, after system startup, outputting address data differing from said predetermined address data, wherein the address data output after system startup includes address data used to access said first storage area of said BIOS-ROM, thereby performing operations according to said basic input/output system stored in said BIOS-ROM;
- and
- address translating means, connected to said data processing means to receive the address data output from said data processing means after system startup, for translating address data output from said data processing means which designates said first storage area to address data which designates said second area of said BIOS-ROM.
1 more element
A personal computer comprising:
- a BIOS-ROM comprising a flash memory having a first storage area which reserves a read-only boot area and a second storage area which stores a first basic input/output system, said first and second storage areas being distinguished from each other by a predetermined bit of address data, a far jump instruction being stored in a predetermined location of said boot area;
- an external storage device for storing a second basic input/output system;
- a switch for inputting an instruction to transfer said second basic input/output system from said external storage device to said BIOS-ROM;
- a central processing unit for, immediately after power-on reset, outputting predetermined address data to access said boot area of said BIOS-ROM, thereby executing said far jump instruction, and for, after system startup, outputting address data to access said first storage area of said BIOS-ROM, thereby performing operations according to said first basic input/output system stored in said BIOS-ROM, said central processing unit determining, by virtue of the execution of said far jump instruction, whether or not said transfer instruction is input from said switch, and further determining whether stored data of said BIOS-ROM is correct or not when said transfer instruction is determined as having not been input from said switch, said central processing unit transferring said second basic input/output system from said external storage device to said BIOS-ROM to rewrite said first basic input/output system stored in said BIOS-ROM in a first case where said central processing unit determines that said transfer instruction has been input from said switch and in a second case where, when said central processing unit determines that said transfer instruction is not input from said switch, said central processing unit determines that the stored data of said BIOS-ROM is incorrect, said second basic input/output system being automatically transferred from said external storage device to said BIOS-ROM in said second case;
- an address translating circuit, connected to said central processing unit to receive at least a predetermined bit of said address data output from said central processing unit after system startup, for inverting a logical value of said predetermined bit, and for outputting the address data including the inverted bit to said BIOS-ROM;
- a masking circuit connected to said central processing unit to receive said address data, for masking, after system startup, address data which is included among said address data output from said central processing unit and which designates said second storage area, thereby preventing said BIOS-ROM from being accessed;
- and
- a flip-flop for setting said address data translating circuit and said masking circuit to an enabled state when said central processing unit determines that the stored data of said BIOS-ROM is correct.
5 more elements
A personal computer comprising:
- a BIOS-ROM comprising a flash memory having a first storage area which reserves a read-only boot area and a second storage area which stores a basic input/output system, said first and second storage areas being distinguished from each other by a predetermined bit of address data, a far jump instruction being stored in a predetermined location of said boot area;
- a central processing unit for, immediately after power-on reset, outputting predetermined address data to access said boot area of said BIOS-ROM, thereby executing said far jump instruction, and for, after system startup, outputting address data to access said first storage area of said BIOS-ROM, thereby performing operations according to said basic input/output system stored in said BIOS-ROM;
- and
- an address translating circuit, connected to said central processing unit to receive at least a predetermined bit of said address data output from said central processing unit after system startup, for inverting a logical value of said predetermined bit and for outputting address data including the inverted bit to said BIOS-ROM.
1 more element
A personal computer comprising:
- a BIOS-ROM comprising a flash memory having a first storage area which reserves a boot area and a second storage area which stores a basic input/output system, said first and second storage areas being distinguished from each other by a predetermined bit of address data;
- a central processing unit for, immediately after power-on reset, outputting predetermined address data to access said boot area of said BIOS-ROM, and for, after system startup, outputting address data to access said first storage area of said BIOS-ROM, thereby performing operations according to said basic input/output system stored in said BIOS-ROM;
- and
- an address translating circuit, connected to said central processing circuit to receive said address data output from said central processing unit after system startup, for translating address data output from said central processing unit which designates said first storage area to address data which designates said second storage area of said BIOS-ROM, and for outputting address data designating said second storage area to said BIOS-ROM.
1 more element
Dependencies are inferred from the claim text.