Re: vortex memory upgrade?

[Kim Flint <kflint@annihilist.com>]

At 12:39 AM -0800 11/17/99, b.knox wrote:

>"Audio memory consists of 64K x 4 DRAMs, which provide a total of 2
>seconds of
>delay. The unit may optionally be configured with 256K x 4 DRAMs, with
>the
>addition of U10."
>
>an 8 second vortex? eeep um that would be er, nice.
>
>no other mention is made of this "memory upgrade" except in the actual
>schematics...
>the U10's look like they make up an extra bit of the DRAM controller ..
>part number 74HC125 (what are the little triangles again? capacitors?)
>...  it
>looks as though the routing to the DRAM chips must be completely changed
>to get
>the 256K's in there... i'm not too sure... U10 is included in the
>schematics as "spare".. don't know if they're actually inside the box
>... getting ye olde 256K DRAM should prove entertaining enough anyway...
>
>i've emailed both lexicon and Bob Sellon (of jamman upgrade fame) about
>this but with no response ... anyone heard of such an upgrade?
>
>i'd really like to know if 8 sec / dual 4 sec vortex bliss is possible
>in this universe ...

I looked at my vortex schematic. If you want to try this, looks like you
need to pull out the existing dram chips, U15, U18, U20, U21. Add in 256kx4
drams chips at U16, U17, U19, U22. (They have part# 44256 on the schematic,
that may correspond to an actual part. You can probably find them surplus
somewhere.) The you add in tristateable buffer chip 74HC125 at U10, which
brings out an additional address line to the dram.

Whether software will recognize the additional memory is a whole other
matter. Looks like fun though, someone should try it and let us know how it
comes out.

kim

______________________________________________________________________
Kim Flint                   | Looper's Delight
kflint@annihilist.com       | http://www.annihilist.com/loop/loop.html
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