Last updated: 14 December 1999

Adjusting the Autostar Beep Frequency

Mike here: The following is not endorsed by Meade Instruments Corporation. Neither Meade, myself, my service provider, nor the submitter of this tip can be held liable for any damage to people or property that may occur from following this tip. Use this tip at your own risk. Do not try this unless you absolutely, positively need to change the frequency.

From: Dick Seymour (rseymour@wolfenet.com)
The thirty-odd step path to nudged beep frequencies:

The following ONLY pertains to Autostar 495 version 1.3c
The suggested changes don't do -much- to the beep frequency
 (much to my surprise... it should have lowered it by an octave).
But you can experiment, and if you find a better value, we can
 explore how to make it "permanent" (at least until the next Autostar

Print this out for reference before actually trying it on the Autostar.
 (hmmm... you're ex-Air Force? make it a checklist)

Step one: connect the Autostar to your PC serial port via the rs232
Step two: start your favorite "terminal emulator" program and tell
  it to talk to that port at 9600 baud.
 [If you don't have a "favorite terminal emulator program", do:
  If you didn't install Hyperterminal from the Windows 95 CD,
     do it now before proceeding.]
 (start-->programs-->accessories-->hyperterminal   should open a
 "folder window"... one of the icons will be Hypertrm.exe
 Click on that.  You'll get a window with a "New Connection" dialog
 box in from of it.  Name the connection "telescope", and click "OK"
 The next dialog box will be entitled: Phone Number.
  The bottom entry field in that box is a "drop down" field, probably
   showing your modem's name.  Click on the [v] (down arrow) to show
    more choices.  Two of them should be COM1 and COM2.  Click on the
 one you've got the telescope connected to.   Click OK.
 Now you'll see a COM1 Porperties box.  Set it to 9600 bits per second,
   8 data bits, No parity, 1 stop bit, No flow control.  Click OK.
The dialog boxes will go away, leaving you facing Hyperterminal's
 normal window.  Before we go further, click on the [File] choice
 on the upper menu bar, and click "Save".. that'll add an Icon in the
 HyperTerminal "folder window" for future use.]
where were we? oh, yes: Autostar plugged in, Terminal Emulator running,

Step three: turn on the Telescope.  Tell it a date and time, and use
  the MODE key to get out of trying to align it.  Do NOT set it to
  "Download".  Just sitting at "Select Item:   Object" is fine.
     (isn't that nice?)
Step four:  Click in the Hyperterm window to guarantee "focus" there.

 *note* in the following steps, do NOT hit the Enter key unless told to.

Step five:   type a control-F   (hold the Ctrl key down, hit F )
Step six:   the letter A (or P, if you're set up for Polar mode)
              should appear on the screen.  If it does, we're off
               and running.  If it doesn't, please tell me what you
-did- see.
Step seven:  type a control-B  (hold the Ctrl key, hit B )
Step eight: you should see:  At Breakpoint: 00
                             Stack Reg = 7ECD  <--this may be different for a 495, that's OK
                             In Debugger>

Cool, huh?
Step nine: type the "a" key.  It should complete the word "address"
             and sit with the cursor to the right of the word.
Step ten: enter the number:   006900    (no enter key, remember?)
Step eleven: it should list four rows of numbers, all pairs of zeros
   to the right of the colons (:).  If you see something else, don't
    proceed further, just let me know what you see. Jump to Step 23
     (below) to escape.. or simply turn off the telescope.
Step twelve: type the letter "p"  ... it should complete the word
Step thirteen:  enter the number 6900   (no leading zeros)
Step fourteen:  it should start a new line with  6900:00=
Step fifteen:  enter  C6
Step sixteen: it will respond by showing the c6, and then starting a
              new line with   6901:00=
Step seventeen: enter the following numbers, one digit pair to each
           prompt     entry
            6901:00=   0f
            6902:00=   b6
            6903:00=   69
            6904:00=   df   <--- 495 (497 was e3)
            6905:00=   7e
            6906:00=   2c
            690A:00=   83
            690B:00=         hit the Enter key (finally!)
Step eighteen: It will return to   In Debugger>
Step nineteen:  enter the letter "p"... it should complete the word
Step twenty:  enter 2c80
Step twenty-one:  as with step 17 above, do:
            2c80:B6=  7e
            2c81:69=  69
            2c82:df=  00   <--- 495 (497 -was- e3,  you still enter 00 )
            2c83:8a=         hit the enter key.
Step twenty-two: It will return to   In Debugger>
Step twenty-three:  type the letter "g"  it'll say "go" and the Autostar

             will be back in regular operation.
Step twenty-four: Now do something to make it beep.  I told it to
       try to GOTO Mercury after Mercury was below the horizon,
      That allows me to BEEP by simply hitting GOTO again (and again).
  At -this- moment, the BEEP is unchanged.
Step twenty-five: Type a control-B again.  You should get back to
                     In Debugger>
Step twenty-six: type the  letter "p"... it should complete the word
Step twenty-seven: enter  6901
  **the number it will show you (0f at the moment) is the duration of
      one-half cycle of the beeper's tone.  Although i thought doubling
      that should lower the tone by an octave, it didn't.  Fiddling with

       it affected the tone, but didn't lower it much... many values
       -raised- it to very high pitches.  If that works for you, **do
Step twenty-eight:  to the   6901:0f=     enter a different number.
   This is a two-digit Hexadecimal value (0f=15 decimal).
   I've tried small changes (0E, 0D, 10, 11, 12) and large changes (41).

    After entering a number, to the next  6902:B6=  hit Enter.
Step twenty-nine: to the In Debugger> enter "g"
Step thirty: go to step Twenty-Four (24) above.  Repeat until bored.

Turning off the scope will erase all evidence of playing.
The above procedure is merely to test different Beeper durations.
Once (if?) you find one you can hear better (or at all), we can explore
 how to make it permanent (one way: patch the Auto.Rom on your PC, and
  re-download the entire thing to the Autostar.... it's a one-byte

Good luck

Oh: what did you -do-?
  You entered a program at address 6900 which loads the 68hc11's B
register with 0F
     (or whatever), then it loads the A register with the value from
69DF (69E3 in a 497, v1.3c) (69e6 in a 497 with v1.3b),
     then Jumps to 2c83.
  Then, at 2c80 you replaced the original "load A from 69DF" with a JUMP
     your tiny program at 6900.
   2c80  (2c84 in version 1.3b) is the "beep"subroutine called by
      most parts of the Autostar... the B register controls the
frequency, the stack
    contains (usually) an 800 (hex) which controls the duration.
Changing the frequency also changes the duration, just because it takes
longer to perform
the x800 (2048.)   cycles of B's duration.
Hacker heaven.


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Copyright ©1999 Michael L. Weasner / etx@me.com
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