^ma 1 80 ^pl 0 ^ju
^sk0HP-41/TIMER CHIMES  
^sk1Recently when my watch was away for repair for a while I 
found myself in need of a program to give me 
periodical alarms without any need for the alarms to be acknowledged.  
The ordinary timer alarms on the HP-41 do not repeat 
unless acknowledged.  
The following short program QTR gives a signal on each quarter-hour 
if it is set off by an interrupting 
control alarm programmed with the alpha message 
//QTR, the Z repeat interval 0.15  and the current date and 
starting time in Y and X, using XYZALM.  
Each signal consists of a number of BEEPs corresponding 
to the quarter, with four BEEPs for the full hour.  
At the same time the alpha register 
displays the clock time.  
The original program was rather unfriendly in that it cleared the whole
of the stack and alpha registers, so that any program running on the quarter-hour got 
disrupted.  This version preserves X, Y, Z and T but alters L and the alpha register, 
so quite a lot of programs will resume 
after the alarm without disruption.  
In order to start the sequence of chimes, a second 
interrupting control alarm can be set up 
(for example, with a 24-hour repeat interval to give early morning calls).  
This alarm actuates another short program that simply sets up alpha, Z, Y and X registers to 
start calling QTR as from the next following quarter (use the TIME function to read the 
clock, chop the result to the last quarter and add a quarter), 
executes XYZALM and quits.  
Those of us who haven't got a CX can only cancel 
these alarms from the catalogue unless someone 
goes to the effort of writing an SP 
routine to track down the alarm 
buffer and alter it directly.  
To save battery power the final RTN in the QTR program 
can be preceded by OFF, SF11.  
This brings any interrupted running program to a halt, 
but it will restart at next switch-on.  
^sk1Terry Stancliffe