vortex memory upgrade?

["b.knox" <b.knox@latrobe.edu.au>]

hi all ... 

due to buying a questionable-condition vortex at a hugely inflated price
(and easily one of the best purchases i've made to date ;) the beasty
arrived with the service manual instead of the user manual (no
complaints) 

hang onto your chairs 'texter users ... page 4 in the "theory of
operation" section: 

"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 ... 

brad