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Path: detroit.freenet.org!aa122
From: aa122@detroit.freenet.org (John F Davis)
Newsgroups: comp.sys.cbm
Subject: Re: DIP switches inside RAM cart for VIC-20?!?!
Date: 12 Aug 1995 01:24:49 GMT
Organization: Greater Detroit Free-Net, Detroit, MI
Message-ID: <40gvt1$7cm@detroit.freenet.org>
References: <183324Z07081995@anon.penet.fi>
Reply-To: aa122@detroit.freenet.org (John F Davis)
NNTP-Posting-Host: motown.freenet.org
In a previous article, an225234@anon.penet.fi (WhiteH2O) says:
>Any speculation on why those switches would be in there, or what would happen
if I started to monkey around with them?
Well Andy, Wondering why you had to post this via anon.penet.fi...
The 8 K ram cartarge could be configured in any of four different places
(Without my programmer's refference manual I can't remember all of them
but the last one was C000 (hex). They are called block 1, 2, 3 and 5
however. Four of those switches are likely addressing switches to set
the base address of the cartarge. If the cartarge is used the other four
may well be to set the address of the other 8K (That is to say, You may have
a 16K cartarge there). If memory serves (And it usualy does) the original
8K expander cartarge was only half populated and you could expand it to
16 by adding the proper chips and changing from a 4 switch dip switch to
an 8 (or adding a second 4 switch job) I did that in fact.
Normally switch 1 would be block 1, Switch 2 - 2 Switch 3 - 3 and switch 4
is block 5.
Then switch 5 is block 1 bank 2 and so on.
To set them first turn them all off, Then turn fire up the vic (It matters
not if it's plugged into the VIC) and not the bytes free. Now turn off VIC
turn on switch 1 and plug it in. Turn on and note bytes free, Should have
increased, if it did not then turn off, turn off 1 and turn on 8,
If turning on 1 gave you more memory then turn on six
If turning on 8 gave you more memory turn on 3
This should (If it's a 16k box) give you yet more memory
Do not turn on two switches in the same half (IE: 1 and 3) as this will
mess things up a bit.
****WARNING**** When you plug in an eight, sixteen or 24 K expander the
video memory, which used to be at the TOP of BASIC, moves to what used to
be the BOTTOM of basic and start of BASIC (memory that is) Moves up (I think
it's 1/2 K) to make room for it so any programs which use direct pokes to
the screen and or which contain embedded M/L may well not work with the extra
memory plugged in. Unless I've had at them of course (I alaways wrote
"Transportable" code which would run no matter what memory configuration you
had. And with both a 24K and 3K expander plugged into an multi slot daughter
board, along with a 40/80 video card, I could really mess up the old start
of, end of and video pointers <G>
--
John F Davis In Delightful Detroit, Mi. aa122@detroit.freenet.org
"Nothing adds excitement to your life like something
that is clearly none of your business!" Battista