US 4,905,140 AGranted

Semiconductor integrated circuit device

AssigneesHitachi, Ltd., Hitachi Microcomputer Engineering Ltd.

InventorsYasuhiro Sakakibara, Isamu Kobayashi, Yoshinori Suzuki

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Abstract

In a one-chip microcomputer, an EPROM is formed together with a ROM and RAM on one semiconductor substrate. Data such as fixed data necessary in the microcomputer can be changed by the use of the EPROM. In case data are to be written in the EPROM, an EPROM writer is used. This EPROM writer outputs write data to the EPROM and checks (or verifies) the data written in the EPROM immediately thereafter. If any error is detected, the subsequent data write is interrupted. In order to inhibit the unnecessary operation interruption in case the address designated by the EPROM writer comes out of the range of the EPROM, the checking (or verifying) data signal to be fed from the one-chip microcomputer to the EPROM writer is forcibly set at a level which indicates satisfactory operation of the EPROM.

Claims15

Dependent claims

A one-chip microcomputer comprising:

a bus;
a microprocessor coupled to said bus;
a random access memory which is coupled to said bus and which is coupled to said microprocessor via said bus so that said random access memory is accessed by said microprocessor, wherein said random access memory has a first predetermined address space defining a range of addresses assigned to the random access memory;
an electrically programmable read only memory which has address input terminals and data input/output terminals coupled to said bus and which is accessed by either said microprocessor or from outside of said one-chip microcomputer, wherein said electrically programmable read only memory has a second predetermined address space defining a range of addresses assigned to the electrically programmable read only memory;
a first external terminal coupled to said bus for transmitting an address signal from the outside of said one-chip microcomputer to said bus when said electrically programmable read only memory is accessed from the outside of said one-chip microcomputer;
a second external terminal which is coupled to said bus via input/output means and to which either data signals to be read from said electrically programmable read only memory or data signals to be fed to said electrically programmable read only memory are provided;
discriminator means responsive to said address signal for discriminating whether or not said address signals is within the second predetermined address space of said electrically programmable read only memory;
and
means coupled to said input/output means and responsive to an output signal of said discriminator means for setting the data signals to be outputted to said second external terminal at a predetermined level indicating satisfactory operation of said electrically programmable read only memory if said address signal designates an address other than those within the second predetermined address space of said electrically programmable read only memory to prevent an improper indication of error in the electrically programmable read only memory.

6 more elements

A microcomputer comprising:

a bus;
a microprocessor coupled to said bus;
a random access memory coupled to said bus, said random access memory being accessed by said microprocessor and having a first predetermined address space defining a range of addresses assigned thereto;
an electrically programmable read only memory having address input terminals and data output terminals each of which is coupled to said bus and being accessed by either said microprocessor or from outside of said microcomputer and having a second predetermined address space defining a range of addresses assigned thereto, wherein said electrically programmable read only memory is accessed from the outside of the microcomputer to write data into to the addresses within the second predetermined address space and to check the data written thereinto;
a first external terminal coupled to said bus and for providing an address signal from the outside of said microcomputer to said bus when said electrically programmable read only memory is accessed from the outside of said microcomputer;
a second external terminal for receiving either data signals to be written into said electrically programmable read only memory or data signals to be read out from said electrically programmable read only memory when said electrically programmable read only memory is accessed from the outside of said microcomputer;
discriminator means responsive to said address signal and for discriminating whether or not an address signal designated by said address signal is within the second predetermined address space;
and
providing means responsive to an output of said discriminator means and for providing a data signal having a predetermined level to said second external terminal when the address designated by said address signal is not within the second predetermined address space and for providing the data signal to be read out from said electrically programmable read only memory to said second external terminal when the address designated by said address signals is within said second predetermined address space.

6 more elements

A one-chip microcomputer including a random access memory, an electrically programmable read only memory capable of programming data constituting a program thereto from outside of the one-chip microcomputer and a microprocessor coupled to said random access memory and to said electrically programmable read only memory via bus and for executing a predetermined data processing operation in accordance with the program stored in said electrically programmable read only memory, wherein said microprocessor is capable of accessing a predetermined address within an address space which includes a predetermined first address space defining a range of addresses assigned to said random access memory and a predetermined second address space defining a range of addresses assigned to said electrically programmable read only memory, and wherein said electrically programmable read only memory is accessed from the outside of the one-chip microcomputer to store and check the data, said one-chip microcomputer comprising:

a first external terminals coupled to said bus and for providing an address signals from the outside of said microcomputer to said bus when said electrically programmable read only memory is accessed from the outside of said microcomputer;
a second external terminal for receiving either data signals to be written into said electrically programmable read only memory or data signals to be read out from said electrically programmable read only memory when said electrically programmable read only memory is accessed from the outside of said microcomputer;
and
means responsive to said address signal for providing a data signal having a predetermined level indicating satisfactory operation of said electrically programmable read only memory to said second external terminal when said address signal designates an address not within the second predetermined address space.

1 more element

Dependencies are inferred from the claim text.