WTERM

WTERM is my own TRS-80 terminal emulator (written in Z80 Assembly), for use with my recently completed RS232 adapter. Although the RS232 board I wired up is 100% compatible with the true Radio Shack offering, and works as such, the software was a bit lacking. I tried out a couple programs for using the RS232 port (Omniterm and Matrix ALgorithim), and found a few problems for the things I wanted to do (connect to a Linux box and work with the command line):

• No cursor control. I want an ability to put the cursor anywhere on screen (Omniterm does have this, but it has other problems).
• CR and LF are both the same. This is a big one - on pretty much any other terminal, these have 2 different purposes. CR makes the cursor move to the start of the line, and LF makes the cursor move one row/line down (and stays at the same column). The existing programs presumably use the TRS-80 ROM routines to drive the screen, and I don't think it has these features. Instead, either a LF or CR will make the cursor move to the start of the next line. This is a problem for Linux, which always sends CRLF. Even after editing the terminfo source to try to turn one of these signals off, it seems as though it's baked in. Some of the terminal programs like Omniterm try to suppress one or the other, but I found it doesn't work very well. Some Linux programs will send one or the other, fully expecting standard usage.
• Too slow. The TRS-80 is only 1.77 mhz, and the RS232 does not use interrupts. So, anything that happens which is not reading the RS232 data stream in means that things can be easily missed. In particular, scrolling the screen upwards in most existing programs seems to use the ROM routines, during which time the UART cannot be read. Therefore, most terminal programs can only do 600 baud maximum, because any faster and some data will be lost during the time it takes the screen to scroll upwards.
• No handshaking. RTS/CTS are not used for anything. In most programs they are toggleable for general purpose, but not for handshaking. Omniterm is supposed to support XON/XOFF though.