vic-1110 8k ram cart upgrade (and other solutions)

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pallas
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vic-1110 8k ram cart upgrade (and other solutions)

Post by pallas »

hello,

on the wiki page:

http://sleepingelephant.com/denial/wiki ... _Cartridge

it says:

"Some VIC-1110 have also been upgraded to 32k RAM by adding 64 kilobit (8k x 8 ) SRAM chips instead of the 16 kilobit (2k x 8 ) normally found in the VIC-1110 and VIC-1111. This type of upgrade is considerably easier to perform on the VIC-1110 because of the IC sockets left empty by the missing 16 kilobits SRAM chips present in the VIC-1111."

looks like a cool and simple way of expanding to 32k, using mostly original hardware.

anybody did this?
where to find the needed chips?
I'm a software guy looking for answers hehehe ;)

thanks!
Last edited by pallas on Tue May 14, 2013 2:05 am, edited 1 time in total.
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eslapion
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Post by eslapion »

I did! Works great!

You even have one left IC footprint if you want to add the 3k RAM section or some ROM upgrade.

I did this back around 1994. Never had to modify or repair my boosted VIC-1110 since. I even added a small reset pushbutton.

There are hundreds of different brands of 8k x 8 static RAM which will do the job.

This is one of them:
http://www.ebay.ca/itm/LH5164A-80L-SHAR ... 3cbb3d5162
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Post by 6502dude »

eslapion wrote: There are hundreds of different brands of 8k x 8 static RAM which will do the job.
If anyone is looking for 8K SRAM chips, send me a PM.
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pallas
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Post by pallas »

Thanks.

I was wondering if this is worth buying:
http://pages.ebay.com/link/?nav=item.vi ... 0888292725
Since it is untested...

And how many chips are needed?
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buzbard
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Post by buzbard »

I also thought about upgrading a VIC-1110, so I started searching for chips and looking at data sheets for those chips.
Then in the middle of all this research I had another idea, and it was even simpler than the first idea.

Since I had 2 Super Expander cartridges (VIC-1211A) I thought why not just add a 32k chip to it and have a full 35k cartridge (the Super Expander has 3k built in and a spot for a 24 pin chip). The Super Expander PCB is exactly the same as the 3k RAM cartridge (VIC-1210).

So, I found a HY62256A (from China for $5), a 74LS08 (eBay $4) and bit of soldering and I now have a 35k RAM cartridge.
My next step would be to add switches to select individual blocks and to Enable/Disable the Super Expander chip.
Ray..
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eslapion
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Post by eslapion »

buzbard wrote:Since I had 2 Super Expander cartridges (VIC-1211A) I thought why not just add a 32k chip to it and have a full 35k cartridge (the Super Expander has 3k built in and a spot for a 24 pin chip). The Super Expander PCB is exactly the same as the 3k RAM cartridge (VIC-1210).

So, I found a HY62256A (from China for $5), a 74LS08 (eBay $4) and bit of soldering and I now have a 35k RAM cartridge.
My next step would be to add switches to select individual blocks and to Enable/Disable the Super Expander chip.
Nice alternative!

Easy and cheap!
pallas wrote:Thanks.

I was wondering if this is worth buying:
http://pages.ebay.com/link/?nav=item.vi ... 0888292725
Since it is untested...

And how many chips are needed?
It is worth buying.

You need 3 x chips of 8k x 8 (the easier solution IMHO) or, as buzbard suggested, a single 32k x 8 chip along with a 74LS08 to reencode the extra 2 address lines.

Added edit:
If you have a VIC-20cr, you can actually have the 32k x 8 installed inside your VIC by piggybacking it on top of one of the 2 2k x 8 SRAM chips and add the 74LS08 somewhere on top of the glue logic chips.

You'll get a VIC-20 with internal 32k ram expansion.
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Post by Boray »

Super Expander is in first hand a basic extension to add graphics and sound commands to basic, so it contains a ROM as well. So if you would like to keep the ROM you wouldn't be able to add 32K RAM but just 28.
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buzbard
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Post by buzbard »

You can add 32k to the SuperExpender but you can't have block5 RAM and the SE selected at the same time, you'll need a way to toggle the block5 line between them and also you'll have to disable the power to the SE ROM pin(24) when RAM is selected.
Ray..
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pallas
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Post by pallas »

Instead of getting a commodore 8k ram expansion as originally planned, I had a closer look at the 16k "asem" expansion I already had (since '85) and discovered some interesting info:

- it has dynamic ram instead of static
- it has 2 ram chips and 2 empty fingerprints
- it is market 3 - 16 - 32 :-)
- it has one switch (3k / 16k) and 2 empty switch fingerprints

so I ordered the 2 missing chips from china and, after 45 days, got them and installed.
after playing with the switches and changing a couple of soldered dip-switches I finally have my 24k expansion :)
now I need to add the bank 5 and support for 3k by means of switches.
finally I'll be adding the reset switch and I think I'm done!
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Post by rhurst »

Nice! 8)
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eslapion
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Post by eslapion »

imperiousVIC wrote: I can figure out that the expansion port of the vic-20 has 14 address inputs, A0 to A13. The HY62256A has 15 address inputs. A0 to A14. What I would like some help with is exactly how do I hook up the 74ls08 with respect to the extra address lines?

I already have burn't and modded a c64 with Custom Rom chips, so physically hooking it all up is no problem, just the grey area with respect to what to do with the 74ls08.
The VIC-20 expansion port has address OUTPUT lines. In this specific case, only A0 to A12 are used. 13 address lines creates a logical space of 8192 units.

The LS08 is used to create A13 and A14 which the HY62256A requires. It does so by ANDing signals BLK1, BLK2, BLK3 and BLK5. Also, the Chip Select line of your ram chip is triggered by access to any of the above BLK areas which requires a cascaded ANDing.

There are 4 logic gates in a 74LS08 and they are connected as follows:

Gate 1: BLK1 AND BLK3 to A14
Gate 2: BLK1 AND BLK2 to A13 (also sent to Gate 4)
Gate 3: BLK3 AND BLK5 to Gate 4
Gate 4: A13 AND (output of Gate 3) to Chip Select

This allows the VIC which is normally designed to address memory in areas of 8k to use a single 32k SRAM chip.
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pallas
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Post by pallas »

Here is an expansion which is almost like mine, it uses a similar layout (even though a lot more clear!) and chips:

http://www.ebay.it/itm/16K-Speichererwe ... 795wt_1399

I believe it can be easily upgraded to 32k, but don't take my word for it :-)
It does have a fingerprint for a bigger chip, maybe to fit a flash rom?
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