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MORE ON SOUND FOR YOUR PET

Last issue, an article appeared in the COMMODORE MAGAZINE which explained how to connect an audio amplifier to the CB2 line on the user port. Ordinarily, there is no harm in making the connection directly as shown in that article. However, it is possible that you may be using an amplifier which, either due to a malfunction or by an uncommon design, will present the CB2 line with an overload condition. Since there is no overcurrent protection for the CB2 line, it would be wise to provide such protection for the CB2 line yourself. This is simply done by inserting a 100K, 1/10 or greater watt resistor in series with the signal line (ie. pin M or centre conductor of cable) as shown in the following illustration. This will protect the CB2 line even if there is a short at the other end of the patch cord or even in the cord itself.

If you own an 8032 or the 12" display 4016, you will no doubt be aware the computer produces sound without the aid of any add-ons thanks to the internal 'speaker'. Consequently, running programs with sound included, will work without any soldering or screwdriving. Experiment with sound in your program, as it can be a very valuable addition e.g. it draws attention to when an input is required or accepted.

When the salesmans back is turned, try this one line instruction on an 8032 to change the 'chime time'

POKE 23l,150: PRINT CHR$()

The following table is of use when programming with sound as it gives the musical note equivalents to the poke values.

POKE 59467,16 to enable sound.

POKE 59466,51 generates a pleasant square wave. Also try values of 10, 14, 15, and 85.
POKE 59464,0 is silent. The following values are for the musical note equivalents listed.
tB below first C
Bb=251 C =237 C#= 224 D =211 D/t- 199
F =177 F$=1 67 G =157 G#=149 A =140 A#=132

B =124
Cl =117
Cli=111
Dl =104
Dllt= 99
El = 93
Fl = 88
Fl'= 83
Gl = 78
Gllt= 73
Al = 69


10 POKE 59467,16: POKE 59466,51
20 LET X=INT(255*RND(TI)+1)
30 POKE 59464,X
40 FOR I=l TO 250: NEXT I
50 POKE 59464,0
60 FOR l=lT0250: NEXT I
70 G0TO 20

1 POKE 59467,16: POKE 59466,10
28 FOR I=l TO 1O
30 FOR U=255 TO l STEP-1
40 POKE 59464,U
50 NEXT U
60 NEXT I
70 POKE 59464,0

NOTE: Always remember to restore the cassette functions by POKEing everything back to 0.