M82 replica help

So for the past few days I have been researching as much as possible about the M82, now i am new to the whole NES modification scene and only have basic knowledge of circuitry. ( I at least can identify parts with a little poking around )
My questions are as follows:
1. is it possible to make a pre-cart boot system kind of like the game genie and the 100-1 units have ( menu system )
2. how to go about switching between the carts because I know for a fact that switching the +5v is not the answer (data lines drawing power as well)
3. a push-button counter switch circuit (having a hard time finding one)

I have more questions and I am sure there will be more but I can't think of any at the moment, any help would be appreciated

This is going to be much more obnoxious and probably more expensive than you want it to be, although you'll find some things are a little cheaper (parts) and some things are a lot more expensive (PCB) if you actually build a 12-up device.

It sounds like you already read this thread?

Extending the concept to a 1-of-N device is straightforward, but won't have to use the same parts; you might find the 74'138/'238 (8 or 16 up) / '139/'239 (4 up) sometimes useful.

Using a pushbutton to rotate between cartridges would probably be best done with with an analog debounce circuit on the button and a counter like a 74'161; other options may be better depending on specifics.

google chinese multicarts. It's all there.

- I figured this project would be some difficulty as to its process' of both hardware and software, the whole idea is to build the M82 over a period of time so as to alleviate the issue of high expenses, I think the end result would out weigh the blood and sweat put into its completion.



- I did have a glance but most of these concepts are new to me as I am a beginner if you have any must need research material that would be appreciated



-1-of-n ? i have never heard of this term before, is it a acronym for 1 of (1,2,3,etc...) and if so again a reference for this would be great, as for the 74'138/'238 and the '139/'239 there eprom chips?



-with a quick glance this looks like the appropriate chip as i can apply multiple in a chain to increase count ( do you know if it has support for outing to a set of 7-segment display drivers? )



-I don't know how having a multi-cart would be helpful as it doesn't utilize any functions that I require aside from the use of a menu which i could use to flash the M82 start-up splash screen but i don't beleive that will allow me to jump out and into a bank of games as the cart on its own is a stand alone unit, i could be wrong but thank you for the input.

-if anybody has an idea about enabling the system to use the M82 boot system that would be great. i have an idea where you could set a custom cart with the splash screen set to activate first before the rest of the circuits when tripped by the timer, and being activated by the input on the left controllers select keystroke.

I'm not really certain what the right way is to teach 30-year-old digital logic design. It feels easy to me so I'm kind of flailing at figuring out where to start.
You could try OpenCourseWare's older Intro To Digital Logic lab class; but I have no idea if it's the best way to go about it. I've also got this ancient copy of "How To Build Your Own Working Microcomputer" by Charles Adams (1980). It's an interesting read, aims you at understanding the 8080 (but a lot of the knowledge will carry over), but it's definitely not worth paying a premium to get it specifically. (I picked it up from a used bookstore for $4)

Yes, N as any number, it's not specific to engineering
No, they're digital logic ICs, try googling any one of: 74hc138 74hc139 74hc238 74hc239.

It does not, you could use an external IC for that like the 74hc4511 (or any of its myriad predecessors: search wikipedia's articles on the 7400 and 4000 family for seven- or 7- segment)

- sorry I was lost for a bit I do some what under stand the logic of BCD ( I get lost easily, but with enough research I can truck on again) it definately helps to get a few books which I will look into.



- I figured just had to double check ^_^



- after I posted this I slapped myself across the face, I realized that I knew exactly what they were I just didn't put two and two together kind of stupid of me really but I blame a long day at work ^_^



- I looked into the other chips and I have found the appropriate set of chips to enable the circuit to count and display (from my local electronics retailer), but I have a few more questions about chip functionality, for instance to send a signal to the rest of the circuit ie. enable a set of IC's that control the disconnected portions of each 72 pin. what would I use, would I use the output of the 7 segment or the output of the connectors from the decade counter/ synchronous counter?

- I apologize for any garbled sentences -

Maybe try http://openbookproject.net/electricCircuits/Digital/ ?

Either of the latter, depending on how you design the rest of the circuit. The seven-segment driver output is probably not useful for this purpose.

- what if I were to use a second counter series tied in parallel to the other counter circuit and used the secondary as a switch to activate some kind of relay bank for each

- is there a IC or something similar with the ability to turn on and off say about 6 channels while having one input to activate these traces
attached example image

If signals are only going through one way, or only one way at a time, that's what the 74'244 and 74'245 do.

If you actually want signals to go through both ways, you want an analog switch like the CD4016. (Note that you probably don't want that—it's much higher resistance than the tristatable buffers)

- Thanks, the 74'245 looks like the circuit I need it has capacity to go both ways which i think is needed for the logic circuits that will be disconnected by the IC, for the signal coming from the counter to the transceiver IC would that go in through the ENABLE and the DIR goes to ground?

Have you looked at the Playchoice 10? There are full schematics available, if you want to see how Nintendo did it (just ignore the Z80 and everything it controls).

- Yes i have seen the Playchoice 10, thank you for the suggestion I will look into the schematics if I come to a dead end on my own personal method using the IC's lidnariq suggested.
- the thing about the playchoice 10 was that it was designed to be used in an arcade so units themselves are going to be a little easier to come by and the price isn't going to be as steep, but the M82 caught my eye because of its difficulty to come across, when I complete this project i'll have a unique item for my friends and family members to enjoy (albeit it will be a replica and not the real deal).

1- Be careful with the /IRQ line; you'll need to do something different with it relative to all the other lines
2- A design that used the 74'244 or 74'245 is thinking about this as "Which cartridge slots are the ones I'm connecting to the CPU".
You could also design this thinking as "Which signal is the one that gets heard?" by using the 74'138, 74'151, and 74'238.

Anyway, both designs should be fine.

- thank you for the alternative chips I hopefully will be getting the parts from the store tomorrow i'll notify you if I have a glitch.

I will be away for approximately 4 weeks, I am taking my supplies with me, if I get the chance I will tinker away but you Won't hear back from me till early September


Captain419

Hello once again NESDEV community,
Its been awhile, I have been busy with work and lots of various activities.
I have some new revisions to my circuit plan and i beleive this is now the correct way
To go about the construction.
I will give a more detailed plan soon but i thought i would just let you all know

Well as promised here is a progress report on what I have come to design (still in the non-physical realm) I am still currently awaiting components like the 72 pin connectors and the Arduino itself (which will be a Arduino Mega due to the vast amount of digital and analog I/O).
so I will post some images of the general layout (pic 1), the boot rom I have come to learn uses a NES-NROM-128 ( I don't know what game boards use it, if anyone has a suggestion ).

Any questions or advice is accepted and greatly appreciated.

-Captain419-

M82 Rom Info


Arduino Pin Assignment

Circuit Layout (didnt want to attach to previous post)

I have a question that I need clarifying, I have some doubles of a few NES games lying around and I was wondering if the NES-UNROM mapper 2 would be suitable for a NROM-128 mapper 0 cart ( I read/heard somewhere that that was possible) and if so how can one go about doing that.

p.s. it's a 128k cart (all extra's)

Captain419

EDIT: Gahh, I completely forgot about CHR-ROM. One way is to patch the ROM so that it loads the CHR-ROM from PRG-ROM when the program boots.

Other way is to modify the board to use CHR-ROM, but I'm not going to even attempt to explain that correctly. Since the PRG-ROM would be 16 KB in this case, the PRG part wouldn't need any rewiring.