Using an EPROM in a SuperCartridge game to play 48k sized homebrew

[Barakandl]

I have successfully used a Pole Position II cartridge PCB to play Beef Drop by inverting the chip select. I want to do the same to a SuperCartridge so I can play 48k sized games.

 

I have a Hat-Trick. I desoldered out the original masked ROM and installed an IC socket. Using the information at http://www.atarimax.com/jindroush.atari.org/7800cart.html Isee....

 

W2 & W6 & W7 - mutually exclusive
W2 - read only rom in 8000-FFFF area, /CS low
W6 - read only rom in 8000-FFFF area, CS high
W7 - linear rom in 4000-FFFF area, /CS low.

 

 

Does that mean for hat-trick. W2 out and W6 in and then I can use a 27512 EPROM????

 

More questions.... 27512 is a 64k EPROM... the images are 48k.... Does that mean i pad the file with junk to fit 64K??? If so do i pad the beginning or pad the end??

 

I have PCB design software and i have made NVRAM adapters for pinball. http://nvram.weebly.com. I could easily make EPROM boards for 7800 games. I know how to do a 32k sized eprom now... super easy layout i could make quickly. I could do larger sized games too. Is this kind of thing needed? The blank PCBs i could have made for a dollar each. The inverter IC, DIP28 socket, and EPROMs are all cheap too.

Anyone have the 7800 edge connector made in eagle they want to share before i do it myself?

 

Thank you

Andrew

 

[Barakandl]

I'm stuck until i get EPROMs in from eBay. I don't have any 512Kbit or 1Mbit on hand... thought i did, but those are about the only sizes I am missing. I guess i don't use those in pinball machine MPUs.

 

Here is what I got.

 

 

The center bottom is a Pole Position Cart. I inverted the CE per some guide i fond. This works great playing Beef Drop on a 27256 EPROM.

 

Top left is from a Hat Trick. I desoldered out the masked ROM and installed an IC socket. I am going to try and put a 27512 EPROM in this board. Pad the binarie to fit 64K and play with various jumpers. I see a 74LS02 I hope one of these jumpers can be used to make that NOR gate invert a chip select as is probably needed.

 

Top right is from a Jinks. This one had a 6264 RAM in it... interesting. I wonder if software MOds could be done to use a FM1608 NVRAM there, which has the same pinout typically of 6264, to keep track of high scores or other things like audits in a arcade machine. I am going to try and use a 27C010 EPROM in this board... again play with the jumpers to see if i can find what works.

 

Any tips on using EPROMs in original carts is greatly appreciated.

[CPUWIZ]

If there is something specific, you want to accomplish, send me a PM. I have designed and have had many different PCB's manufactured for the 7800. All homebrews sold on AA are using my boards. But if you just want a challenge and re-invent the wheel, it is fun and I'd say go for it.

 

If you want more info, search for threads I started in this forum, I currently do not have the time to provide you with a bunch of links.

[Barakandl]

Ultimately i want a cart i can drop in a 32kb EPROM into, cart i can drop a 64KB into, and a cart that i can drop 128KB EPROM into so i can play around with various homebrew games. I'd like to do this myself using original carts if possible. I do PCB work for a 2nd job so I am very proficient removing and installing components. If repro boards make the most sense to get EPROMs going, i will go that route.

If the aftermarket boards are already made, that is great, i don't really need to do the edge connector component and pcb layout.

 

I will mine your posts for more information. I have been striking out searching for detailed jumper info on these boards.

 

Thanks

Andrew

[+Mitch]

Do you mean like this: http://www.atari7800.org/boardscans/C100339.txt

and this: http://www.atari7800.org/boardscans/C300565.txt

 

Mitch

[Barakandl]

Thank you Mitch! That is what i was looking for. I should be set now.

 

Have you guys ever looked at into using flash RAM for high scores? I see 6264 RAM is already used. Really easy to get FM1608 NVRAM in its place. Typically always work unless the CE is out of time.

 

I will have to look at the CPUWIZ eprom carts now too see if there is anything else that needs done I can help with.

 

Thanks

Andrew

Edited March 17, 2016 by Barakandl

[Barakandl]

Been thinking about it.....

 

since there is no multi 7800 carts available... in the mean time it wouldnt be too hard to make a 32KB eprom cart with a large EPROM on it. Dip switch bank to choose game, and address decoding to map it all out..... Find some cheap donor game, cut a hole in the cart so you can reach the dip switches......

 

think i found a project

[CPUWIZ]

Been thinking about it.....

 

since there is no multi 7800 carts available... in the mean time it wouldnt be too hard to make a 32KB eprom cart with a large EPROM on it. Dip switch bank to choose game, and address decoding to map it all out..... Find some cheap donor game, cut a hole in the cart so you can reach the dip switches......

 

think i found a project

 

Done that, except it is menu driven and not with dip switches.

 

[SoundGammon]

Where can I get one?

[CPUWIZ]

Where can I get one?

 

Sorry, they were gone two years ago.

[Barakandl]

 

Sorry, they were gone two years ago.

Yeah... i did't think anything like this was available. I am in the middle of doing a few pinball machine NVRAM adapter projects. Hopefully i don't lose interest in the atari and I will do some EPROM boards. I found someone posted the 2600 card edge connector for eagle. That was going to be the only thing that was remotely a challenge.... getting the edge connector perfect. Rest is easy.

[+frankodragon]

Unfortunately, someone poo-pooed on CPU about piracy and no more carts were ever made.

[phoenixdownita]

Been thinking about it.....

 

since there is no multi 7800 carts available... in the mean time it wouldnt be too hard to make a 32KB eprom cart with a large EPROM on it. Dip switch bank to choose game, and address decoding to map it all out..... Find some cheap donor game, cut a hole in the cart so you can reach the dip switches......

 

think i found a project

http://atariage.com/forums/topic/224038-multicarts-suggestions/

 

I did multicart dipswitch based for all the 7800 official releases for my own personal consumption.

One cart for all the 32K or less, one for the 48K, 4 for the 128K (2 collection for 128K games proper, one collection for 128K + RAM, one smaller collection for 128K + 16K [in this one I cheated and even games that were 128K only got the extra 16K as copy of page 6]).

 

Anyway I used old Atari PCBs [donated by CPUWiz] modded to host a bigger eprom and added dip switch with pull ups where needed.

The only one off was the small cart (32K or less) as they were all inverted.

(also the Activison cart is different only recently santosp reversed engineer the PAL/GAL I used an original Rampage instead)

 

I am pretty sure coming up with a PCB for each "kind" or even one PCB to rule them all is not that hard having time and energy to dedicate to it.

 

Even using a "SW dip switch controller" without a new mapper is not crazy hard, again no time and lost interest.

[My plan was to have the "menu" code being copied over the 16k RAM [at 4000-7fff] and entirely run from there at which point the higher 32K can be freely prepared and jumped into as needed after having configured the proper mapper.

the complex part would have been for the games that have 16K or ROM right there, all the rest would have been fine.

For those I was envision a delay circuit in which the switch from RAM to ROM of that area is prepared but delayed and the jump to the end of the 64K space would be the final trigger to execute the swiitch for those games that need it.

 

Now this is all fine and dandy but as Linus Torvald says "talk is cheap, show me the code" and I've got nothing so I just vomited here the line of thought I had at the time before I was content with my artisan dipswitch multis. In the end once you get the gist of it it's more "carpentry" than electronics as I needed to modify PCBs and cart shells.

 

CPUWiz approach for his multi was to create a new 1M mapper and "fixup" the games so they access the correctly remapped portions ... I think it worked mostly but a couple of games didn't get 100% fixed before the release if memory serve. I think it was a much more ambitious plan but it did require somewhat less complex hardware.

 

The Harmony Concerto should be the SD card based solution that satisfy all needs anyway.]

[+frankodragon]

Speaking of padding, I found an old thread about how to pad a 48k to 64K here. Programs such as 7800Basic have no 64k compile option so padding is the only way.

[Barakandl]

27512's came today. 48/64KB games work a treat in the Hat Trick cart if you pad the beginning of the file with junk. Going to play some b*nk later tonight. wooo

Ran into a snag with 128KB games.... they dont make EPROMs in 28 pin since EPROMs need 32 pins for programming... doh! Anyone have a pinout for the 128KB masked proms used in a 7800 cart like Jinks? I am thinking that the 128KB masked PROMs like in my Jinx cart follow the same pinout as a 27C301. If so I think there is space to float the extra four pins and tie them to VCC which should make a 27C301 work in place of a 28pin 128KB masked prom.

[+Mitch]

If memory serves 27C100 is what you want. You can use the more common 27C010 but it's bit of a pain since you have to flip two of the pins.

 

Mitch

[Barakandl]

check the pinout of 27c301 (probably the same as 27c100???) I am thinking i can float pin 1,2, 32, 31 out of the 28 pin socket. Use a little fine wire and tie those floating pins to VCC and hopefully that matches the pinout to the masked PROM atari used. Does anyone know the part number for the 1Mbit masked PROMs atari used so i can check the pin out? I suppose i could map it out with the edge connector since i do have that info, but.... that would be work =D.

 

[phoenixdownita]

check the pinout of 27c301 (probably the same as 27c100???) I am thinking i can float pin 1,2, 32, 31 out of the 28 pin socket. Use a little fine wire and tie those floating pins to VCC and hopefully that matches the pinout to the masked PROM atari used. Does anyone know the part number for the 1Mbit masked PROMs atari used so i can check the pin out? I suppose i could map it out with the edge connector since i do have that info, but.... that would be work =D.

 

You surely do not want to tie /OE to VCC or nothing will work, that one has to be tied together to /CE or simply to GND, your call.

I usually left the other actually floating with no ill effects (I usually use a 27C010 and rewire the few traces needed (I think there's 2 pins to reroute not a biggie)).

If you design your own PCB then there's nothing to reroute or float and you can use 27c010/020/040/080 and compatible with no issue.... if you read my thread about making all my dipswitch based multi you'll see there are pictures where those 4 extra pins of a 27c801 (27c080 is the same) are spread out at the base (from a 32 pin socket not the chip though) and are wired as needed.

[Vcc to Vcc, /OE to either GND or /CE as I saw fit, the other 2 ignored in a 27c801 there's no /PGM or /VPP or /OE dedicated pins anyway but just extra Addressing pin, even easier as those are where the DIP switches connect]

 

 

Here are the difference between 27c010 and 27c301 if you decide to reroute 2 signals:

[+Mitch]

I've never used the 27C301 but it does look like the same pinout. I usually run /OE to ground and the other three to +5v.

 

Mitch

[Shawn]

I've never used the 27C301 but it does look like the same pinout. I usually run /OE to ground and the other three to +5v.

 

Mitch

 

A16 of the eprom still needs to go to hole 22 of the pcb (I know you know this Mitch but the OP might not) The rest being pulled high is better than floating them for sure.

[Barakandl]

Thanks everyone.

 

I think a16 will be in the correct place with 27c301 and pins 1,2,31,32 floating out of socket, no? That is why I was going to use the 27c301 because a16 is at p24, not at p2 like 27c010.

[phoenixdownita]

Thanks everyone.

 

I think a16 will be in the correct place with 27c301 and pins 1,2,31,32 floating out of socket, no? That is why I was going to use the 27c301 because a16 is at p24, not at p2 like 27c010.

I must be on someone ignore list.

 

Which part of this picture is not clear?

 

 

Yes all the pins from 3 to 30 of a 27C301 match the mask rom pins from 1 to 28, so yes deal with 1,2,31,32 separately.

1,2 to GND and 31,32 to VCC. If you prefer 2 can be connected to 22.

[Barakandl]

I must be on someone ignore list.

 

Which part of this picture is not clear?

 

 

Yes all the pins from 3 to 30 of a 27C301 match the mask rom pins from 1 to 28, so yes deal with 1,2,31,32 separately.

1,2 to GND and 31,32 to VCC. If you prefer 2 can be connected to 22.

Damn... kind of abrasive.... Yes your picture and post is very clear and it provided me with information i was looking for. Thank you

 

I should have quoted shawn i guess since my last post was in response to him. I will confirm by buzzing out the edge connector where a16 goes....

[Barakandl]

My GQ-4X burner does not like 27C301 or my EPROMs are bad. I get a message in the gq-4x software when i set the burn profile to 27C301 that says "The GQ-4X need connect ZIF pin 2 to chip pin 24". I assume that means exactly what the pic phoenix posted, swap 2 and 24. I made an adapter stacking two IC sockets on top of each other. It did not work an i got write error immediately saying it read back FF unexpectedly checking the first write. I thought maybed the IC socket adapter was not sitting well in the burner zif socket, so i made another adapter using SIP ic connector header posts and a protoboard, flipped 2 and 24 per the message in the gq-4x software and the same thing.

 

I guess i will get different eproms to try. I burn lots of eproms for pinball machine computer boards. wouldnt be the first or last time i had bad ones.

 

thanks

andrew

[Barakandl]

Here is a pic of the cart board setup for 27c301. I moved a bypass cap to a 0805 sized smt at some traces near the ROM and I moved a zero ohm resistor the backside of the board to ft the overhang of the new socket. I bent out the 4 extra socket leads and attached ground to a convienent trace nearby. For the +5v pins i ran a small wire that went to a nearby via.

Does anyone know if when U2 is setup for a 6264 sized ram if it uses one chip enable or both chip enables. If just one chip enable it would be easy to make carts with built in NVRAM for high scores using a device like FM1608. I have hundreds of those NVRAMs. Software would have to be made to use the onboard NVRAM tho i don't know how to do that.

 

Edited March 26, 2016 by Barakandl