Write circuit for an erasable programmable read only memory device of a microcomputer
First Claim
1. A write circuit for an erasable programmable read only memory device of a microcomputer, said microcomputer including a program counter for providing an address and operating in synchronization with machine clock signals, said write circuit comprising:
- a clock generating circuit, coupled to receive an external clock signal and the machine clock signals, for supplying a clock signal to said program counter in response to the external clock signal and the machine clock signals so as to successively increment the address produced in the program counter, the external clock signal having a frequency lower than the frequencies of the machine clock signals, the clock signal having different frequencies during a normal operation mode and a write-in operation mode so that the address produced in the program counter is successively incremented in synchronization with the machine clock signals during the normal operation mode and is successively incremented in synchronization with the external clock signal during the write operation mode; and
a bit line clock generating circuit, coupled to receive the machine clock signals and a least significant bit of the address from the program counter, for generating a bit line clock signal for inhibiting a write-in data from being written into the erasable programmable read only memory device in response to the machine clock signals and least significant bit of the address during a time period in which the address changes.
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Accused Products
Abstract
A write circuit for an EPROM device of a microcomputer comprises a first circuit responsive to an external clock signal WCLK and machine clock signals for supplying a clock signal CLK to a program counter of the microcomputer so as to successively increment an address produced in the program counter, where the external clock signal WCLK has a frequency lower than those of the machine clock signals and the clock signal CLK has different frequencies during normal and write-in operation modes so that the address produced in the program counter is successively incremented in synchronism with the machine clock signals during the normal operation mode and is successively incremented in synchronism with the external clock signal WCLK during the write operation mode, and a second circuit responsive to the machine clock signals and a bit data of a LSB of the address from the program counter for generating a bit line clock signal BCLK for inhibiting a write-in data from being written into the EPROM device during a time period in which the address changes.
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Citations
10 Claims
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1. A write circuit for an erasable programmable read only memory device of a microcomputer, said microcomputer including a program counter for providing an address and operating in synchronization with machine clock signals, said write circuit comprising:
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a clock generating circuit, coupled to receive an external clock signal and the machine clock signals, for supplying a clock signal to said program counter in response to the external clock signal and the machine clock signals so as to successively increment the address produced in the program counter, the external clock signal having a frequency lower than the frequencies of the machine clock signals, the clock signal having different frequencies during a normal operation mode and a write-in operation mode so that the address produced in the program counter is successively incremented in synchronization with the machine clock signals during the normal operation mode and is successively incremented in synchronization with the external clock signal during the write operation mode; and a bit line clock generating circuit, coupled to receive the machine clock signals and a least significant bit of the address from the program counter, for generating a bit line clock signal for inhibiting a write-in data from being written into the erasable programmable read only memory device in response to the machine clock signals and least significant bit of the address during a time period in which the address changes. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A write circuit for an erasable programmable read only memory device coupled to receive machine clock signals, comprising:
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a bit line driver circuit coupled to the erasable programmable read only memory device; a word line driver circuit coupled to the erasable programmable read only memory device; a program counter, coupled to said word line driver circuit, for providing a write-in address to said word line driver circuit; and a write timing control circuit coupled to said program counter and said word line driver, including; a clock generator circuit, coupled to said program counter and coupled to receive an external low frequency clock signal and a control signal during a write operation, for enabling said program counter to generate a write-in address in accordance with the external low frequency clock signal and the control signal; and a bit line clock generator circuit, coupled to said program counter, said bit line driver and said word line driver, for receiving a least significant bit of the write-in address from said program counter and the control signal, and inhibiting a write-in data from being supplied to the erasable programmable read only memory device from said bit line driver circuit. - View Dependent Claims (9, 10)
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Specification