Printer configured to perform printing on a print-receiving medium and computer-readable medium

A printer comprising:

• a feeder configured to feed a print-receiving medium;
• a printing head configured to form a print on said print-receiving medium fed by said feeder;
• a storage part configured to store a battery that is rechargeable and configured to supply electric power to said feeder and said printing head;
• a connecting part configured to be connected to an external power source;
• and
• a controller,
• the printer being configured to perform printing on said print-receiving medium by cooperation between said feeder and said printing head,
• said controller executing
• an instruction reception process for receiving an update instruction for a content related to said printing,
• a first voltage acquisition process for acquiring an output voltage of said battery stored in said storage part,
• a first determination process for determining whether or not said output voltage acquired in said first voltage acquisition process is equal to or greater than a predetermined threshold value,
• a first update process for updating said content of which the update instruction is received in said instruction reception process in the case that said output voltage is determined as being equal to or greater than said predetermined threshold value in said first determination process,
• a charging process for charging said battery with said external power source through said connecting part in the case that said output voltage is determined as being less than said predetermined threshold value in said first determination process,
• a second voltage acquisition process for acquiring an output voltage of said battery charged with said external power source,
• a charging determination process for determining whether or not said output voltage acquired in said second voltage acquisition process is equal to or greater than the predetermined threshold value, wherein the predetermined threshold value is less than a fully charged value,
• a second update process for updating said content of which the update instruction is received in said instruction reception process in the case that said output voltage is determined as being equal to or greater than said predetermined threshold value in said charging determination process,
• a threshold value acquisition process for acquiring said predetermined threshold value for each of multiple processing stages of said content of which the update instruction is received in said instruction reception process, wherein the multiple processing stages includes a downloading stage of the content, an installation stage after downloading of the content, and a reboot stage of said priner after installation of the content in said update process,
• a threshold determination process for determining a maximum value of said predetermined threshold values respectively acquired in said threshold value acquisition process as a threshold for determining, and
• a use determination process for determining whether or not to use said predetermined threshold value in said reboot stage at a determination in said threshold determination process in accordance with a type of the content.