For my bootloader I need a way to send a file with a terminal program. As my serial connection has only Tx and Rx, but no RTSCTC lines for flow control, it is useful if the terminal program either implements software flow control (XONXOFF), or a delay value for sending a file. What do I do?

To send a file with a terminal program, you may use an open source terminal program, available in the following location:

https://sites.google.com/site/terminalbpp/

It supports sending a file with a delay (as the following figure shows, with 1 ms delay), and supports XON and XOFF.

Figure 1. Terminal Program Window

Tip: Using a zero delay does not work in all the cases. Instead, send a file with a 1 ms delay setting.