PuTTY issues

Question

Strange things happen when I use c3270 with PuTTY. For example:

• Line-drawing characters are wrong (they just seem to be a bunch of q's).
• PF keys generate garbage on the screen or are simply wrong.

Answer

First, you need to make sure that your TERM environment variable is set correctly. It needs to be putty, not xterm or vt100. That usually takes care of both of the above issues.

There is a more subtle issue with PF keys and PuTTY, however. PuTTY has some odd ideas about function keys. Without the Shift key pressed, F1 generates an escape sequence consistent with F1 in the terminfo definition, and so do F1, F2, etc., all the way to F12.

However, Shift-F1, which should (from a 3270 perspective) generate a sequence for F13, generates a sequence for F10 instead. Shift-F2 generates a sequence for F11, etc., all the way to Shift-F10, which generates a sequence for F19. Shift-F11 generates a sequence for F11, and Shift-F12 generates a sequence for F12. There do not appear to be any keys that generate escape sequences for F20, F21, F22 or F23.

Key Pressed

F1

F2

F3

F4

F5

F6

F7

F8

F9

F10

F11

F12

Resulting sequence without Shift

F1

F2

F3

F4

F5

F6

F7

F8

F9

F10

F11

F12

Resulting sequence with Shift

F10

F11

F12

F13

F14

F15

F16

F17

F18

F19

F11

F12

The workaround for this is simple. c3270's default keymap maps the two-key sequence <Ctrl-a, F1> onto PF(13), <Ctrl-a, F2> onto PF(14), etc., all the way to <Ctrl-a, F12> mapping onto PF(24). So if you don't mind a two-key sequence, the problem is solved.