Re: vortex memory upgrade?

[Kim Flint <kflint@annihilist.com>]

At 10:19 PM -0800 11/17/99, b.knox wrote:
>Kim Flint wrote:
>>
>> 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.
>>
>
>thanks Kim !! they wouldn't be the same drams that max out jammans would
>they?

the thing you get for the jammans are memory modules. what you are looking
for here are chips. The modules might have these chips on them, they might
not. You also might find these chips on old 256K simms that were used in
computers 10 years ago or so. Someone familiar with electronics surplus
should be able to find these chips no prob.

>
>> Whether software will recognize the additional memory is a whole other
>> matter.
>
>this is what has me worried ... it really looks like the hardware
>upgrade itself is unfinished, very slim chance of the software
>recognising it ... on the other hand the software seems robust enough in
>other respects ... maybe it's crazy enough to work ... whether the mod
>is reversible is yet another whole other matter.

my guess is if it doesn't recognize the extra memory, it will just work
like it did before. But it might work, ya never know. It could be they were
just trying to keep the hardware cost down and never did this option, but
it's there in the software. Jon Durant would probably know, if he's
actually reading this.

I don't see why you couldn't reverse the mod if it doesn't work. Just take
out the new chips and put the old ones back in.

>> Looks like fun though, someone should try it and let us know how it
>> comes out.
>>
>> kim
>>
>
>yep... wish i had a spare to try it on .. is -fun- the right word ?? :)
>i don't think i have enough confidence with a soldering iron to launch
>into this obviously non-trivial mod...

it's just through-hole parts, probably on a 2 layer PCB. This is actually a
really easy job for someone with a bit of soldering experience. Find
somebody that knows how to solder and you've got nothing to worry about
that I can see. the hard part will more likely be in finding the old dram
chips that match the ones on the schematic.

kim

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