[sdiy] learning from early drum machines?

[Scott Nordlund]

Oops, I had realized that previously (it's really pretty obvious) but for some reason it slipped my mind.  Still it should be possible (with some effort and greater complexity) to achieve the same effect with modern parts.

Of course the TC5501 wouldn't be a good idea for a new design now, even with NOS parts.

The Paia one, if I'm understanding it correctly, requires that everything be written at once (real time only), unlike modern drum machines where the pattern can be edited as it continues to play.

> Date: Mon, 12 Jan 2009 13:46:40 +0100
> From: fanwander at mnet-online.de
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] learning from early drum machines?
> 
> Hi Scott
> 
>> The DR-55 seems like a better design to me.  
> yep, the TC5501 is a nice SRAM chip for drummachines because it provides 
> separate DATA-IN and DATA-OUT, because you can rewrite a single 
> bit(=single instrument) of the half byte, by feeding back the data-out 
> of the other tracks to the data-in (see 
> http://fa.utfs.org/diy/boss_dr55/dr55_schematic.jpg). This is not 
> possible with the usual SRAMs with combined data-in/out port.
> 
> But unfortunately the chip is out of production. I got 7 pieces here in 
> germany from a rare-semiconductors-dealer, and those were the last ones 
> I found.
> 
> Florian
> 
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