VIC-20 Multicart

saundby · Post by **saundby** » Wed Jan 31, 2007 3:35 am

Once I've got time again, I'll fix my Vics and breadboard this up for testing. I've got a selection of 6502s, so I'll drop a ZIF socket into a Vic and give it a try with each, slap a scope or analyzer on and see what there is to see. I'll see if I can drum up any 8M ROMs in a box around here somewhere. I've got a lot of 4M that are pulls from routers, but not much in the way of 8M (at least in x8.) At any rate, with an image to burn I can put together a hardware prototype on a solderless breadboard and do an end-to-end test.

It'll also give me a chance to look at eliminating the extra latch chip, and check those ideas in hardware.

After that I'll hopefully have time to try out some ideas I have about adding a coprocessor to the Vic.

-Mark G.

Schema · Post by **Schema** » Wed Jan 31, 2007 10:16 am

eslapion wrote:I know a couple of places that will do the complete job of making the board and populating it... minimum quantity is 2000 units...

In other words, there is no way you can get only 100 units done like that... AFAIK... and therefore it will have to be done by hand.

Hmm, it must be possible. I'm thinking of products like the Retro Replay or MMC64 on the C64, which certainly have been professionally produced/populated but not in high quantities.

Maybe a couple of hundred units there at most, and they're around $60 US (but seem to be a lot more complicated than our multicart.)

Plus, even at my company, we get small runs of boards made sometimes i.e. around 20 units. And these aren't space-prices either. I'll ask around.

Unfortunately I don't know enough of the lingo yet, beyond "gerber files" and "parts lists".

eslapion · Post by **eslapion** » Fri Feb 09, 2007 1:39 am

OK, I need an education here...

Can anybody tell me EXACTLY what the difference is between 27C080, 27C8001 and 27C801 ?

And don't anybody tell me that one of them is 512kx16 while others are 1Mx8bit because I checked them and all of them are 1Mx8bit.

saundby · Post by **saundby** » Tue Feb 13, 2007 10:38 pm

Different manufacturers and timings, slight differences in power requirements. The pinouts are compatible, the nomenclature for the chip select and output enable will vary by manufacturer, I know the '080 and '801 both have the same sense on their lines (active low) but I don't have an '8001 sheet handy. I'd be willing to bet they're the same, though. If you have a chip in hand it's easy enough to check.

Take the slowest one and check the timings from the data sheet to make sure they're OK for the Vic (I'd be shocked if any of them aren't), then feel free to mix and match. The power differences between the models I'm familiar with are minimal, from the perspective of a Vic.

-Mark

Schema · Post by **Schema** » Fri Feb 23, 2007 12:08 pm

Anything new on this?

Just a heads-up, I'll be away in Ireland (for work) for two weeks starting tomorrow. I will have Internet access, but won't be able to browse Denial and follow this thread as closely as I have been.

I hope to read about some successful breadboard testing of different options when I get back

In March when I'm back, I'll stop by Microart (www.microart.ca) to ask about getting the boards made and maybe populated. They specialize in small runs for niche applications and I've got a contact there now.

KilrPilr · Post by **KilrPilr** » Fri Feb 23, 2007 12:12 pm

Have a good safe trip Leif. Have you made any progress on a menu? I hope eslapion or whoever has some hardware done too. The subject seems to have gone quiet unfortunately. I guess its not as popular of an item as I thought it would be. Either that or everyones just waiting for a finished product.

Schema · Post by **Schema** » Fri Feb 23, 2007 12:17 pm

I've got the menu designed in my head, just need to implement it

I'll be in the middle of nowhere in Ireland so I should be able to send some time on the menu, using VICE.

I'll take that latest ROM set you posted and go through it too.

KilrPilr · Post by **KilrPilr** » Fri Feb 23, 2007 12:49 pm

Leif, grab the file on the server now as I just put the latest on it. Please remember though that this file is missing some games for the final menu.

Post by **Jeff-20** » Fri Feb 23, 2007 2:24 pm

I don't think interest has dropped. I'm very excited about the project. I'm quiet only because I have no skills in this area to contribute. Maybe others are the same way. But I'd be first to buy one!

ral-clan · Post by **ral-clan** » Fri Feb 23, 2007 3:07 pm

If I know the rough size of the board you are going to use, and someone can point me to a generic plastic case that fits this board, I could submit a proposal for some graphic work (i.e. a sticker design).

Schema · Post by **Schema** » Wed Mar 07, 2007 8:15 am

Greetings from the land of Guinness. Work is going well, should be back in Canada on Saturday.

ral-clan wrote:If I know the rough size of the board you are going to use, and someone can point me to a generic plastic case that fits this board, I could submit a proposal for some graphic work (i.e. a sticker design).

I'm still daydreaming about getting custom translucent cases made for the multicart

Ideally the board will be identical dimensions to a normal VIC game cartridge, just a lot more "stuff" on it. But the case should be "thicker" so that socketed ROMs can be used.

I've got a good start on the multicart menu. In particular, I've written a "pseudocompiler" that generates the .bin image of the menu program directly from Leo's Excel spreadsheet

It then takes that and concatenates all the ROM images together into one mondo .bin image for the EPROMs/OTPs, after stripping off the address bytes.

So the tedious portion is now automated, from a software perspective we just need to collect the ROM images and enter them onto the spreadsheet.

Any hardware news?

Also regarding hardware - will a reset button be possible? I expect the way the multicart will be used (at least, the way I plan to use it) is to play a game for a little while, then hit reset and go back to the game menu, and pick another one, on and on.

ral-clan · Post by **ral-clan** » Wed Mar 07, 2007 9:15 am

To keep costs down you could just add solder points for a user mountable reset switch. I don't need one, as my VIC-20 already has one (and I wouldn't want one that could get knocked or would prevent the cart from fitting among other carts in a multislot expander).

eslapion · Post by **eslapion** » Fri Mar 09, 2007 12:53 pm

Schema wrote:I'm still daydreaming about getting custom translucent cases made for the multicart Ideally the board will be identical dimensions to a normal VIC game cartridge, just a lot more "stuff" on it. But the case should be "thicker" so that socketed ROMs can be used.

I've got a good start on the multicart menu. In particular, I've written a "pseudocompiler" that generates the .bin image of the menu program directly from Leo's Excel spreadsheet It then takes that and concatenates all the ROM images together into one mondo .bin image for the EPROMs/OTPs, after stripping off the address bytes.

So the tedious portion is now automated, from a software perspective we just need to collect the ROM images and enter them onto the spreadsheet.

Any hardware news?

Also regarding hardware - will a reset button be possible? I expect the way the multicart will be used (at least, the way I plan to use it) is to play a game for a little while, then hit reset and go back to the game menu, and pick another one, on and on.

Concerning the reset button, it is pretty much like that I wanted the multicart to work in the first place so I don't see any problem there.

As for the cartridge size and sockets, the problem is solved before it even exists. I have an original VIC-1110 8k cart here I modded into a 32k cart back in the early 90's and the 3 8K SRAM I added in it were all on sockets.

Also, the Atarisoft game Robotron 2084 uses a pair of 2764 EPROM internally instead of the normal pair of 2364 ROM chips and the PCB is slightly larger than a normal game. Two well placed drilled holes allow it nonetheless to fit just fine onto (as opposed to into) the retaining plastic brackets.

These are also on sockets and fit just well inside the normal VIC cart case.

What we would need to find now is a plastic molding company to make your transparent cases.

eslapion · Post by **eslapion** » Fri Mar 09, 2007 12:57 pm

ral-clan wrote:To keep costs down you could just add solder points for a user mountable reset switch. I don't need one, as my VIC-20 already has one (and I wouldn't want one that could get knocked or would prevent the cart from fitting among other carts in a multislot expander).

Unfortunately, in this specific case, all your internal reset switch would do is return you to the same game. The architecture would interpret it as the reset signal generated to start to most recently selected game as not all games will start well with only a software reset.

The internal latching system that select the banks also need to be reset and that's why only the reset button located on the cart will return you to the menu.

Schema · Post by **Schema** » Tue Mar 13, 2007 10:19 am

So it sounds like the reset button would have to be a momentary DPST that resets both the '273 and the VIC - right?

I envision the final cart being sold as a bare populated board, so people can optionally put it in a case if they want. How should we install the reset button so it will work in both situations?

As for the case, I remember when making my blue disk utility cartridges, it was very difficult to close the case with a socketed EPROM in there. Hence, the window (which also made it easy to swap EPROMs).

But we might be getting ahead of ourselves here. The first priority is, do we have a working circuit?