Claims
- 1. A communication control system transmitting data between two systems including system A transmitting at a first transmission speed and system B transmitting at a second transmission speed, said communication control system comprising:
- transmission and speed converting means for converting between the first and second transmission speeds when transmitting the data between the system A and the system B, wherein said transmission speed converting means comprises a dual port video RAM including:
- a first port connected to the system A, receiving the data from the system A and transmitting the data to the system A at the first transmission speed;
- a serial access memory, connected to said first port, for storing data;
- a random access memory, connected to said serial access memory, for storing the data; and
- a second port connected to said random access memory and the system B, receiving the data from the system B and transmitting the data to the system B at the second transmission speed; and
- control means for controlling the transmission of the data between said random access memory and said serial access memory, wherein said control means includes:
- a RAM leading address setting register having a leading address for setting the leading address at which the data accumulates in said random access memory; and
- a transmission data capacity setting register indicating a data capacity of the data stored in said serial access memory.
- 2. A communication control device according to claim 1, wherein said control means sets in said random access memory leading address setting register said leading address from which the data is stored in said RAM in said transmission speed converting means.
- 3. A communication control device according to claim 1, wherein said control means sets in said transmission data capacity setting register a number of transmission data words when the data is stored in said serial access memory of said transmission speed converting means.
- 4. A communication control device according to claim 1, wherein responsive to a transmission data write command to said random access memory of said transmission speed converting means generated by and received from the system A, said control means sets said leading address in said RAM leading address setting register, sets a direction of internal transmission from said serial access memory to said random access memory, sets a number of words to be transmitted in said transmission data capacity setting register, controls transmission of the data from said serial access memory to said random access memory after completion of data transmission from the system A to said serial access memory, and requests the system B to read the data from said random access memory.
- 5. A communication control device according to claim 1, wherein, responsive to receiving a command to read the data from said serial access memory to the system A when the data is transmitted from the system B to the system A, said control means sets said leading address in said RAM leading address setting register, internally transmits the data from said random access memory to said serial access memory, controls transmission of the data from said serial access memory to the system A after setting a number of words to be transmitted in said transmission data capacity setting register, and activates a transmitting process for performing the transmitting.
- 6. The communication control system according to claim 1,
- wherein the data includes first and second data,
- wherein said transmission and speed converting means first accumulates in said serial access memory the first data as first accumulated data when the first data is transmitted from the system A to the system B at the first transmission speed, and said first accumulated data is transmitted from said random access memory to the system B at the second transmission speed, and
- wherein said transmission and speed converting means accumulates in said random access memory the second data as second accumulated data when the second data is transmitted from the system B to the system A at the second transmission speed, and said second accumulated data is transmitted from said serial access memory to the system A at the first transmission speed, realizing the transmitting of the data between the system A having the first transmission speed and the system B having the second transmission speed.
- 7. The communication control system according to claim 1,
- wherein when the data is transmitted from the system A to the system B, the system A generates and transmits a data write instruction to said control means of the communication control system, and
- wherein, responsive to said data write instruction received from the system A, said control means sets said leading address of said RAM leading address setting register, determines an internal transmission direction in said dual port video RAM, sets said data capacity of said transmission data capacity setting register, and controls the transmission of the data from the system A to the system B via said serial access memory and said random access memory by requesting the system B to read the data stored in said random access memory.
- 8. The communication control system according to claim 1,
- wherein when the data is transmitted from the system B to the system A, the system B generates and transmits an instruction to said control means of the communication control system, and
- wherein, responsive to said instruction received from the system B, said control means sets said leading address of said RAM leading address setting register, controls the transmission of the data in said dual port video RAM from said random access memory to said serial access memory, sets said data capacity of said transmission data capacity setting register, and controls the transmission of the data from said serial access memory to the system A by requesting the system A to read the data stored in said serial access memory.
Priority Claims (1)
Number |
Date |
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Kind |
2-210396 |
Aug 1990 |
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Parent Case Info
This application is a continuation of application Ser. No. 07/743,886, filed Aug. 12, 1991, now abandoned.
US Referenced Citations (11)
Continuations (1)
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Number |
Date |
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Parent |
743886 |
Aug 1991 |
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