Circuitbenders Forum
Circuitbenders Forum => Drum machines => Circuitbending discussion => Alesis => Topic started by: windspirit on October 10, 2012, 06:32:22 PM
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Hi! First post.
I remember seeing a seeing a website that showed how to use multiple soundbanks on a modified HR-16. Basically you have to solder one ROM pin by pin onto the back of another one except for one pin which is selected by a switch. This makes it so that the output of the ROMs both go to the same place but the ROM that i being used is switchable, aka 2 sound banks.
I cant seem to find the website now. I know about burnkits instructions, but for some reason there is no mention of this technique on that site.
Could anyone who knows what im talking about post the link? Thanks!
~ws
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Another way would be to get the largest capacity 32-pin ROM you can find and concatenate several images together, then use a BCD switch to set the upper address lines. You might need to fiddle a bit to get a suitable firmware ROM, though.
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I am looking for the same thing ! if you find and info can you please msg me..
Ill do the same for you..
regards!
Garry
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Here is some info for you.. and others.. I think its right. please correct me if not.. Ill be applying it when my parts arrive..
1 X 28 pin ; P/N 27C256 : OS Eprom
2 X 32 pin ; P/N 27C040 4 meg: Sound Eproms
can Piggy back with Zif sockets using switch on output enable pins.
Pin 24 output enable - 27C040 with 22k ohm resistor with switch
Pin 22 output enable - 27C256 with 22k ohm resistor with switch
I have a diagram but I have no idea how to post it here. Let me know.. This might work for now..it's the same idea but not same chip.
http://members.optusnet.com.au/tonymy01/magnavox/piggyback.GIF (http://members.optusnet.com.au/tonymy01/magnavox/piggyback.GIF)