*SOLD OUT* 32k RAM expansions for the VIC-20 - 25$ each

eslapion · Post by **eslapion** » Fri Apr 13, 2012 3:03 pm

darkatx wrote:Just got mine already!
Loaded up Realms of Quest III and away she went!
AWESOME!!!!
Thank you so much Eslapion!

Thank you for your comment.

Very happy to have brought you more fun on the VIC.

Muzz73 · Post by **Muzz73** » Fri May 04, 2012 3:52 pm

I would be interested in purchasing one from you if they are.

I see that some of the messages in this string are a few years old, so I had to ask.

Muzz73 · Post by **Muzz73** » Fri May 04, 2012 3:54 pm

I was looking at the wrong date and I see that none of these messages are very old at all.

But I'd still like to purchase a RAM expansion if you have any more.

andym00 · Post by **andym00** » Wed Jan 30, 2013 12:08 pm

I'd so love one of these if there's any still available ?
Probably not a snowballs chance in hell I guess, but what have a I got to lose by asking ?

darkatx · Post by **darkatx** » Wed Jan 30, 2013 3:19 pm

It's was only less than a year ago...it's well worth it!

macc · Post by **macc** » Sat Feb 02, 2013 7:19 pm

Im sure Francois still has there for sale, ive got one too, great item, only thing lacking is a 3k expansion. Give him a pm, im sure he will reply

andym00 · Post by **andym00** » Sun Feb 03, 2013 6:36 am

Fingers crossed

I've always been a bit of a purist in my love of the VIC in it's unexpanded state, but lately I've been playing with and massively enjoying the expanded VIC and its potential there.. Problem is I've no 24K or 32K RAM expansion to test with on the real thing

eslapion · Post by **eslapion** » Sun Feb 03, 2013 4:39 pm

PM sent!

The product is still alive and kicking!

tokra · Post by **tokra** » Sun Feb 03, 2013 6:07 pm

Just wondering: How much more complex would a 35K-expander be? Filling the 3K-hole in BLK0 has advantages apart from being able to play Doom. With just a few POKES you could also this as a 3K-only-expander and play all those games that specifically require the 3K expansion.

Maybe just add a reset-switch and you would have a relatively cheap all purpose RAM-expansion. Don't know how much the price difference would be to the MegaCart or FE3 though to make this worthwhile.

I came upon a very small 32K-expansion on Ebay Germany lately:

http://www.ebay.de/itm/281060409917

Now this looks compact, maybe even too much so.

eslapion · Post by **eslapion** » Sun Feb 03, 2013 6:41 pm

tokra wrote:Just wondering: How much more complex would a 35K-expander be? Filling the 3K-hole in BLK0 has advantages apart from being able to play Doom. With just a few POKES you could also this as a 3K-only-expander and play all those games that specifically require the 3K expansion.

I did the mod of adding the 3K RAM area support for a couple of people. Because the cart port of the VIC maps the 3K ram expansion area as 3 individual 1k sections, I had to use 3 diodes and a resistor to create a diode-resistor AND logic gate and have it control a 8k SRAM chip stacked on top of the 32k SRAM chip.

You waste 5k that way but it is the easiest and smallest solution I found. I can still do it if you're willing to pay 15$ extra for your Expander.

An extra switch was also added to enable/disable the 3K expansion.

Maybe just add a reset-switch and you would have a relatively cheap all purpose RAM-expansion.

You are asking for something that is already included in the 32k expander offered here. There is also a switch to toggle it between read only and read-write mode to make it compatible with game cartridge images and can be used as a disable switch so you don't need to unplug it.

Please look at the images posted earlier:
http://sleepingelephant.com/ipw-web/bul ... sc&start=9

Don't know how much the price difference would be to the MegaCart or FE3 though to make this worthwhile.

The 32k expansion also has a ROM socket to add extra ROM options such as VICMON, Programmer's Aid and Super Expander.

tokra · Post by **tokra** » Sun Feb 03, 2013 7:31 pm

eslapion wrote:I did the mod of adding the 3K RAM area support for a couple of people.[...]
I can still do it if you're willing to pay 15$ extra for your Expander.

Ah, that sounds very nice. So basically $40 for the full 35K + shipping. Sounds like a very good option for those who don't want to spend or wait for a MegaCart or cannot build an FE3. I'm thinking with Doom this option might become more popular

You waste 5k that way but it is the easiest and smallest solution I found.

Would it be possible to map further 2K of this "wasted" RAM to IO2/IO3 at $9800/$9C00 ? Essentially this would make this a 37K expansion. I don't know of any programs that would use this just now, so it's just a theoretical question I guess.

I think MegaCart uses this area to store SJLOAD-Basic for example. It's a nice place to hide for sure

eslapion · Post by **eslapion** » Sun Feb 03, 2013 9:45 pm

@tokra
The trick to add the 3k RAM expansion by using a single 8k SRAM chip is to decode the !RAM1, !RAM2 and !RAM3 lines into only 2 binary lines AND perform a logical ANDing of these 3 lines to the !CS pin of the SRAM chip.

The logical AND operation is done with the 3 diodes and resistor.

An 8k SRAM chip has 13 address lines numbered A12 to A0. A12 is tied to the ground, A11 is connected to !RAM1, A10 is tied to !RAM2, A9-A0 are connected to the cart port normally by piggbacking on top of the 32k SRAM chip.

The binary result is:
3k RAM not addressed: !CS =1 A11=1 A10=1
!RAM1 is addressed: !CS=0 A11=0 A10=1
!RAM2 is addressed: !CS=0 A11=1 A10=0
!RAM3 is addressed: !CS =0 A11=1 A10=1
A12=0 at all times

Making a 37k expansion as you suggest would require a 5 input (RAM1,2,3 and IO2,3) AND gate to the !CS line of the 8k SRAM chip, connecting !IO2 (logical) AND !IO3 to A12, connecting !RAM1 to A11 then connecting !IO3 (logical) AND !RAM2 to A10.

The new binary result would then be:
3k RAM or IO not addressed: !CS =1 A12=1 A11=1 A10=1
!RAM1 is addressed: !CS=0 A12=1 A11=0 A10=1
!RAM2 is addressed: !CS=0 A12=1 A11=1 A10=0
!RAM3 is addressed: !CS=0 A12=1 A11=1 A10=1
!IO2 is addressed: !CS=0 A12=0 A11=1 A10=1
!IO3 is addressed: !CS=0 A12=0 A11=1 A10=0

This represents adding 1 5-input AND gate, 2 2-input AND gates, one memory chip, one switch and about a dozen extra connections to the board.

Ouch!

tokra · Post by **tokra** » Mon Feb 04, 2013 6:17 pm

Thanks for the thorough explanation! Still I'm wondering why older carts did not use the IO2/IO3-area. It would have been a great copy-protection since I don't know of any RAM-expansion that fills this space.

eslapion · Post by **eslapion** » Tue Feb 05, 2013 3:41 am

tokra wrote:Thanks for the thorough explanation! Still I'm wondering why older carts did not use the IO2/IO3-area. It would have been a great copy-protection since I don't know of any RAM-expansion that fills this space.

There is a version of the Rabbit tape accelerator which uses this memory area.

I made a modified version of Turbo disk (Compute's Gazette) that uses it too.

eslapion · Post by **eslapion** » Wed Feb 06, 2013 6:56 pm

Only 8 Ultimate Expanders left!

Denial

SOLD OUT 32k RAM expansions for the VIC-20 - 25$ each

Are these still available?

My mistake...