Posts: 136
Threads: 22
Joined: Aug 2010
I'm not collecting expert, just a 28S fan. IMHO it's not worth it. They're not that hard to come by and just about any non-working key will spoil the calculator.
The 'M' key activates the CONTRL menu which brings up, among other things, the debug features. Also, when programming, any command with an 'm' in it would have to be entered by finding it in the soft menus rather than typing its name.
A quick look shows that there a couple of commands (CLMF, ERRM) which contain an 'm' _and_ are in the CONTRL menu set. To get to them, you'd have to invoke the CONTRL menu by using its menu number (13) followed by the MENU command, which contains an 'm' so you'd have to get to that via the MEMORY menu... You get the picture, I'm sure!