                              MANUAL CALCULATION                             
                             ~~~~~~~~~~~~~~~~~~~~                            
   To start manual calculation, highlight item 3 in the main menu  and  press 
RETURN, after changing any of the options if required. Manual calculation  is 
the normal mode of operation for PRT Calc. It accepts any valid input entered
via the keyboard and immediately displays the result. 
   Firstly it displays a header showing  the  current  settings  of  all  the 
options and then prompts you for an input. If the input is valid (see section 
headed Valid Keyboard Inputs) it then displays both the input and the  result 
in two columns. (The reason it redisplays the input is that it does so  in  a 
consistent, readable format, acting as  a  visual  check  on  the  input  and 
tidying up the printout if enabled). If the printer option has  been  enabled 
then the header and both columns are also printed. If the  input  is  invalid 
then a warning message is displayed (and printed). If the input is only  just 
outside the valid range then a result is given along with a warning that  the 
result is only approximate. 
   When you have finished, or to change any of the options, press RETURN with 
no input. This returns you to the main menu. BUT REMEMBER,  any  results  not 
printed will be lost. Also, any results which  scroll  off  the  top  of  the 
screen will be lost, so it is advisable to enable the printer if more than  a 
screen full of results are expected. The  contents  of  the  screen  can,  of 
course, be printed at any time by pressing the Prt Sc key. 
