XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX  Unitman  XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

                 A comfortable unit manager for the HP48
       Integrates and removes units in the built-in UNITS menu system  

The powerful mashinery of Unitman allows to add user-defined units to the unit
menus, and any unit - whether builtin or added - can be purged from the menus.
You can also add or purge whole unit directories. Thus, the builtin menus can
be completely reorganized. Option ExpU expands the builtin UNITS by just one 
additional directory for converting currencies. Other UnitDir's may be added 
ad libitum. Of particular interest is that the famous 3-fold functionality of
unit keys scetched below works also for user defined units. The commands AddU,
PurU, AUD, PUD for adding or purging units or whole unit-directories will be 
explained in examples.
 
Let's first define the currency EUR (euro) in the new MONEY directory which 
appears in the expanded soft-menu after a first press on AddU or by pressing 
ExpU. MONEY contains only the (US)$ after a first run of AddU. Suppose AddU's
dialog box has already been filled according to our first example as follows:
                 
                    XXXXXXXXXX Add a Unit XXXXXXXXXX
                    UnitDir       MONEY
                    UnitName      "EUR" 
                    Define        .95_$       

The UnitDir MONEY is obtained by scrolling through the UnitDirs with the menu
option CHOOSE. A UnitName must be entered as a string. This allows, e.g., the
creation of names like 'rot/min' (violating the names convention on the HP48).
Define had to be answered in our case since EUR is unknown to the converter. 
Entries under Define must be units with a real before the "_". When entering 
the above, EUR appears in MONEY and any sum of Dollars can easily be converted
into EUR and conversely, cf. below. Both $ and EUR are stored in the current 
directory. For use in any directory, execute AddU in HOME. European currencies
with a fixed exchange are best be defined in terms of EUR.

Next, we want the frequently used unit kW (kiloWatt) to appear in POWR which 
is number 9. This time the dialog box should look as follows: 

                    XXXXXXXXXX Add a Unit XXXXXXXXXX
                    UnitDir       POWR
                    UnitName      "kW" 
                    Define        (can be skipped, need not be filled in!)       

The Define-option may safely be skipped because the system knows the prefix k
and the unit W and hence kW, although a unit name kW did not show up in the 
built-in POWR menu. But with Unitman, it will. Generally, a unit deriving from
existing an unit name by prefixing with D (Deco), h (hecto)... or d (deci)
m (milli)... as listed in the Manual, are known to CONVERT and other commands,
even if not appearing in the original menus. With AddU, you can force it to
appear in the menu! Nothing is written in the HOME directory in such a case.

PurU deletes a user-defined or built-in unit name from a directory. E.g, the 
directory TIME contains Hz on its page which is not a time unit. We put it on
a second page by purging it temporarily with PurU: 

                    XXXXXXXXX Purge a Unit XXXXXXXXX
                    UnitDir    TIME        
                    UnitName   "Hz"  

Next we add the useful ms (millisec) to the units of TIME. Finally, we re-add
Hz, skipping the "Define?:" option in both cases. Then Hz appears on page 2 of
TIME from now on. Other frequency units like MHz are best be added to the new
created second TIME page. Note that you may purge all units you're not pleased
with, e.g, miUS^2. The operating system still remembers them. While a dialog-
box is open one may quietly page through the unit menus as indicated by the 
help text "-page UNITS", to get entries like miUS^2 into the black fields. 
Return to the dialog menu is possible by pressing 0 and ON, for instance.

The commands AUD and DUD (Add and Delete a Unit Directory) work similiar to
to the above. For instance, one may add a directory InfU for Information Units
like bit, byte, KB, MB, GB etc. Define 1_bit = 1_$, 1_B = 8_bit, 1_KB = 1024_B
etc. Be very careful: If the Define option is skipped in AddU, the converter
would yield 1_KB = 1000_B, which is incorrect. Clearly, you may also translate
the directories names into your language, copying the units from the old one 
to a renamed one, and then purging the old (builtin) ones with PUD.

ExpU adds the MONEY directory to the builtin UnitDirs and assigns the UNIT key
74.3. RESET resets temporarily to the builtin units (without leaving the USR 
mode). This may be useful for inspecting the original menus after many changes
have been made. A complete elimination of the expanded UNITS is possible only
by purging the assignment on 74.3. Unitman's command menu is quickly invoked 
by holding the shift while pressing the UNITS key. Releasing the shift before
pressing 74.3 sets the UNITS menu as before. Of particular importance is that
user-defined unit keys operate in precisely the same way as the builtin unit 
keys. These acts as follows (for details see Chapter 10 of the manual):

Nonshift:  Appends (or multiplies) the unit to the stack object in Level 1. 
           E.g., if 10 is on the stack then the $-key in MONEY yields 10_$.
Leftshift: Converts. E.g., if EUR appears in MONEY (see above) then pressing 
           leftshift EUR applyed to 10_$ in the stack yields 10.52..._EUR.
Righshift: Divides. Rightshift $ applied to 100_Hz leaves 100 in the stack.
           Rightshift s "converts" 100 from the stack into 100_1/s = 100_Hz.

REMARK. Be careful in chosing unit-names. E.g., the system reads a unit-name
PS as 1_PegaSiemens=10^15_S. Although this unit has never been used, its name
is blocked and cannot be redefined to denote any other unit. The assignment of
Unitman to key 74.3 is relatively small, even for many user-unit entries. 
-----------------------------------------------------------------------------
 Wolfgang Rautenberg  raut@math.fu-berlin.de  www.math.fu-berlin.de/usr/raut