Printer detecting data precisely in response to change in data transmission speed

A printer comprising:

• an interface control section communicating data with a host computer;
• a print processing execution section performing a print processing based on a print data received from the host computer via the interface control section;
• a synchronizing signal output section provided in the interface control section and outputting a synchronizing signal into the host computer in order to make the host computer transmit the print data to the printer;
• a data reception section provided in the interface control section and receiving the print data transmitted from the host computer at data transmitting speed based on the synchronizing signal;
• a data transmission section provided in the interface control section and outputting a control signal into the host computer in order to control the host computer;
• a command detection section outputting a detection signal when a change command for changing a clock rate of the synchronizing signal in the print data received at the data reception section is detected;
• and
• a control section provided in the interface control section and controlling the synchronizing signal output section and the data transmission section based on the detection signal.

An interface control method in a printer comprising the steps of:

• outputting a synchronizing signal to a host computer;
• receiving a print data transmitted from the host computer at data transmission speed based on the synchronizing signal;
• transferring the print data to an print processing execution section;
• detecting a change command in the print data which instructs to change a clock rate of the synchronizing signal;
• and
• controlling the synchronizing signal and the host computer in accordance with the change command.

A recording medium for storing a printer control program read and executed by a host computer, the printer control program for executing the steps of:

• outputting a synchronizing signal to a host computer;
• receiving a print data transmitted from the host computer at data transmission speed based on the synchronizing signal;
• transferring the print data to an print processing execution section;
• detecting a change command in the print data which instructs to change a clock rate of the synchronizing signal;
• and
• controlling the synchronizing signal and the host computer in accordance with the change command.

A data transfer control method for controlling data transfer between a host computer and a printer in a print system comprising the steps of:

• transmitting a synchronizing signal at a first clock rate from the printer to the host computer;
• starting to transmit a print data in synchronization with the synchronizing signal at the first clock rate from the host computer to the printer;
• transmitting a change command for changing the synchronizing signal at the first clock rate to a synchronizing signal at a second clock rate from the host computer to the printer;
• transmitting a stop request signal for requesting the host computer to stop transmitting the print data from the printer to the host computer;
• changing the synchronizing signal at the first clock rate into the synchronizing signal at the second clock rate specified in the change command and transmitting the synchronizing signal at the second clock rate by the printer to the host computer;
• and
• transmitting a stop release signal for releasing the host computer from stopping the print data transmission from the printer to the host computer.

A recording medium for storing a program for controlling data transfer between a host computer and a printer in a print system, the data transfer control program for causing the host computer and the printer to execute the steps of:

• transmitting a synchronizing signal at a first clock rate from the printer to the host computer;
• starting to transmit a print data in synchronization with the synchronizing signal at the first clock rate from the host computer to the printer;
• transmitting a change command for changing the synchronizing signal at the first clock rate to a synchronizing signal at a second clock rate from the host computer to the printer;
• transmitting a stop request signal for requesting the host computer to stop transmitting the print data from the printer to the host computer;
• changing the synchronizing signal at the first clock rate into the synchronizing signal at the second clock rate specified in the change command and transmitting the synchronizing signal at the second clock rate by the printer to the host computer;
• and
• transmitting a stop release signal for releasing the host computer from stopping the print data transmission from the printer to the host computer.