How to hack cartridges

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eslapion
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Postby eslapion » Wed Jul 25, 2007 8:37 pm

6502dude wrote:Should it read:
A13 AND (/BLK2 AND /BLK5) to /CE + /OE


There is an error on the last line but not this one.

It should read:
/BLK1 AND /BLK3 to A13
/BLK1 AND /BLK2 to A14
A14 AND (/BLK3 AND /BLK5) to /CE + /OE

My apologies.

It looks like your way of fixing it would work well too.

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6502dude
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Postby 6502dude » Thu Jul 26, 2007 11:50 am

eslapion wrote:It looks like your way of fixing it would work well too.


Often there are multiple ways to come up with same result. :)

I really like the idea of using 74LS08 instead of '148.
:D
Image Mega-Cart: the ultimate cartridge for your Commodore Vic-20

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6502dude
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Postby 6502dude » Thu Mar 13, 2008 1:26 pm

Here is another cartridge hack.

This one is based on previous 16K logic, but uses a 27C256 eprom and a push button switch with select between one of two 16K game ROM images.
A cutout was made at rear of the case for the switch and it is glued in place.

Keeping recycling in mind, the switch used to be the low voltage power on switch for a PC.

Image
Image Mega-Cart: the ultimate cartridge for your Commodore Vic-20

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6502dude
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Postby 6502dude » Sat Apr 26, 2008 5:18 pm

I was looking for a solution for MegaCart nvRAM chip which had two problems:
- physically height is large and this presents problems to fit a case
- DS1225 nvRAM has lithium battery and will fail after about 10 years.

I found a relatively new nvRAM chip technology which solves both of these problems.
The chip has two internal 8K memories - 8k SRAM and 8K flash.
Upon power down, an external capacitor provides enough energy for an automated process to start - copy of 8K SRAM to 8K Flash.
When chip is powered up, 8K Flash is automatically copied to 8K SRAM.

I bought a bunch of these chips this week, they arrived on Friday, and have tested for past couple of days and they work great for intended purpose for MegaCart.

The spec sheet indicated data retention of 100 years and chip height is no larger than standard SRAM.

This work also inspired my latest 8K hack cartridge. :wink:

Image

With this cart I can save any 8k ROM image to nvRAM, power off and the game/utility will autostart when Vic-20 is powered back up again. It behaves just like a normal auto start cart.

A switch was added to disable chip so Vic-20 can start in Basic and new game/utility could be stored.
Otherwise, I would stuck with same game/utility for the next 100 years :lol:

Here is image of completed cart:
Image
Image Mega-Cart: the ultimate cartridge for your Commodore Vic-20

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carlsson
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Postby carlsson » Sun Apr 27, 2008 1:52 pm

It really looks neat and I already have an idea for what it can be used for.
Anders Carlsson

Image Image Image Image Image

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6502dude
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Postby 6502dude » Sun Apr 27, 2008 5:00 pm

carlsson wrote:It really looks neat and I already have an idea for what it can be used for.


Great!

I'm going to build a couple more of these.

I will send you one.
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nbla000
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Postby nbla000 » Tue Apr 29, 2008 3:30 am

This latest hack is very useful, you don't need an eprommer to program the chip like the other hacks, just your vic.

1) Switch the cart to NO Autostart
2) power on the VIC
3) Switch the cart to Autostart
4) Load the file for /BLK5 (LOAD"FILE",8,1)

5) Reset or switch OFF/ON the vic and Play :D



Brian just a question:
When you switch to NO Autostart, the 8k is addressed to /BLK3 or is simply off ?
In the first case by switching to NO Autostart you may use /BLK3 tools like Programmers AID or VicMon too.

Another use for NO Autostart on /BLK3 is to use the cart with a vic expander in addition of a standard 16k RAM expansion so you have a 24k ram expansion too.
This is a polyfunctional hack (RAM o ROM) not to bad...


PS: Maybe i will release a special Tetris Deluxe version for this hacked cart to save hi-scores directly on it, so better then a simple Vic-Cart.

PS2: I will release an hi-scores saving version of Tetris Deluxe for MegaCart too :wink:
Mega-Cart: the cartridge you plug in once and for all.

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carlsson
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Postby carlsson » Tue Apr 29, 2008 6:18 am

Yes, games with highscore lists is exactly what I have in mind. Not Tetris, but another game. Of course it is possible to save highscores to e.g. floppy disk too, but a rewriteable cartridge is even more handy.
Anders Carlsson



Image Image Image Image Image

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6502dude
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Postby 6502dude » Tue Apr 29, 2008 7:00 am

The switch currently just disables nvRAM chip.

Great idea to make it control between BLK3 / BLK5.

eslapion
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Postby eslapion » Fri May 02, 2008 8:56 pm

I found this device which appears to do exactly the same thing.

However it seems not to be available in DIP package.

What brand did you use?

This little guywould be nice to make a completely non volatile version of the Ultimate Expander.

I'll have to check pricing on this things, there are much higher capacity version that could be very useful for another project I have for the Commodore 64.

That's real neat! You just remove (or disconnect) the storage capacitor and the memory goes back to volatile state making it very easy to toggle.

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nbla000
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Postby nbla000 » Sat May 03, 2008 8:50 am

eslapion wrote:This little guywould be nice to make a completely non volatile version of the Ultimate Expander.


Yes, not too bad an Ultimate Expander that the user may reprogram.

You may start it switched to RAM, when the vic is powered on, switch it to ROM and you may load your program for /BLK5, much more easy for /BLK3 of course.

Does exist a similar chip with 1/2 MegaBytes or more ?
I think is the easiest way to implement a "MegaDrive" for the Vic, i have some ideas to implement a menu that, using a similar MegaCart hardware logic, a user may store/read any programs for unexpanded/3k/8k/16k vics instead of carts.
Mega-Cart: the cartridge you plug in once and for all.

eslapion
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Postby eslapion » Sat May 03, 2008 12:10 pm

nbla000 wrote:Does exist a similar chip with 1/2 MegaBytes or more ?


Yes it does.

I think is the easiest way to implement a "MegaDrive" for the Vic, i have some ideas to implement a menu that, using a similar MegaCart hardware logic, a user may store/read any programs for unexpanded/3k/8k/16k vics instead of carts.


Personally, I believe the Flashcart, with a 32Mbit flash chip and full 32k+3k ram expansion, would have been adequate as is to create a Megadrive. Essentially, all that's needed is adequate drivers and software.

However, replacing the standard flash memory chip with a nvsRAM chip would allow people to direcly "poke" data into the permanent memory withput the need for a special software.

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6502dude
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Postby 6502dude » Sat May 03, 2008 1:54 pm

eslapion wrote:
nbla000 wrote:Does exist a similar chip with 1/2 MegaBytes or more ?


Yes it does.


512K x 8 nvsram was announced in early mid Q3 2007, with production availability expected in Q1 2008.
However, nothing bigger than 32k x 8 appears to be available for 5 volt logic.
This makes interfacing with Vic-20 TTL a bit more of a PITA.

Personally, I believe the Flashcart, with a 32Mbit flash chip and full 32k+3k ram expansion, would have been adequate as is to create a Megadrive. Essentially, all that's needed is adequate drivers and software.


Seems to me I had heard this before :roll:
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6502dude
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Postby 6502dude » Sat May 03, 2008 2:08 pm

eslapion wrote:What brand did you use?


Simtek

would be nice to make a completely non volatile version of the Ultimate Expander.


Yes, I also thought about doing a 32k hack cart.

Simtek version of 32k x 8 chip - http://www.simtek.com/product-informati ... K14C88.pdf

I'll have to check pricing on this things, there are much higher capacity version that could be very useful for another project I have for the Commodore 64.


Future Electronics seems to have best availability for nvsram chips. They ship out of US via UPS and you should have order delivered in about 3 days.

http://www.componentsuperstore.com/Stor ... ame=SIMTEK

Simtek will also send free samples.

http://www.simtek.com/simtekSite.php?page=product&pk=4

I received two 8K chips on same day my order from Future Electronics arrived.

Use Future Electronics site with caution, some datasheets to not match up with part#s.
Image Mega-Cart: the ultimate cartridge for your Commodore Vic-20

eslapion
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Postby eslapion » Sat May 03, 2008 3:11 pm

6502dude wrote:512K x 8 nvsram was announced in early mid Q3 2007, with production availability expected in Q1 2008.
However, nothing bigger than 32k x 8 appears to be available for 5 volt logic.
This makes interfacing with Vic-20 TTL a bit more of a PITA.


A 74CBTD16211 or other member of the same family makes 5V/3V interfacing very easy.

Thanks for the information about simtek chips.


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