|HP-41 angular modes & system flags|
Message #8 Posted by Karl Schneider on 6 Nov 2006, 10:28 p.m.,
in response to message #1 by Pat
How do I get my 41CV out of radian mode?
Monte Dalrymple provided the answer in this lengthy thread to a very simple question, but I'll add a bit more. The angular mode is represented by the status of two flags (0 = clear; 1 = set):
Alpha Code Flag 42 Flag 43
Degree DEG 0 0
Radian RAD 0 1
Grad GRAD 1 0
The user can check the angular mode in a program by testing these two flags with the "FS?" or "FC?" command. Unfortunately, the user cannot directly alter these flags to set the desired display mode (at least, using only HP's built-in capabilities).
In fact, all flags numbered 31 and higher are system flags that the user cannot directly control. Why is that? I can think of a few reasons:
- The user ought not to be able to control many of these flags (e.g., flag 49 -- low battery).
- The user could set the flags to an indeterminate value (e.g, flags 42 and 43 both set).
- Specific commands are provided which will set these flags appropriately (e.g., DEG, RAD, FIX, DMY)
The user can control USER mode by setting or clearing flag 27. This is handy to use within a program in lieu of commands that might be called "USERON" and "USEROFF", or if the USER button is broken.
Flag 48 (ALPHA mode set) is a system flag. What if the ALPHA button is broken? The only answer I know is to read the ALPHA command via the Wand.
Edited: 7 Nov 2006, 2:01 a.m.