They are, they're friggin' giganormous!
I'm sure I posted this in the series of threads we had last year on terminal keyboards, but just for the sake of brevity: The Boscom 122-keys are for AS-400 terminals, rather than mainframe terminals. So, there are some differences. However, they are plug-and-play compatible with PCs and Windows. There are keys - especially along the left side - that send odd scancodes. At least one of them works as a 'Windows' key, though.
Here's the keychart I made for the left side with the key label at the top and the return value below unshift, shift, ctl, and alt:
SYSRQ/ATTN PAUSE/BREAK
----- -----
ESCAPE PAUSE
SHIFT-ESC SHIFT-PAUSE
CTRL-ESC CTRL-BREAK
ALT-ESC ALT-PAUSE
--/CLEAR ERINP
------ ------
PAUSE DELETE
SHIFT-PAUSE SHIFT-DELETE
CTRL-BREAK CTRL-DELETE
ALT-PAUSE ALT-DELETE
PRINT/SYSRQ HELP/HEX
------ ------
PRTSCR ALT-F1
SHIFT-PRTSCR SHIFT-ALT-F1
CTRL-PRTSCR CTRL-ALT-F1
ALT-SYSREQ ALT-F1
APPS PLAY
------ ------
LWIN ALT-F5
SHIFT-LWIN SHIFT-ALT-F5
CTRL-LWIN CTRL-ALT-F5
ALT_LWIN ALT-F5
START RECORD/PAUSE
------ ------
APPLICATION ALT-F3
SHIFT-APPL SHIFT-ALT-F3
CTRL-APPL CTRL-ALT-F3
ALT-APPL ALT-F3
And, of course, the other frustrating thing about the Boscom is the editing keys layout above the cursor keys. I never did get used to the odd setup, so after a week or two I gave up and redefined it to the PC standard with AutoHotKey and swapped around the keycaps. I was never comfortable with the cross cursor keys, either. I'd often hit the 'Home' key in the center.
That all being said, the Boscom 122 was a fine piece of buckling spring technology. If it's your cup of tea, you really can't go wrong with it - if you've got the real estate!