2708 - 2716 programming

[andrewsm]

Totally! so you can actually have two games programmed into your eproms and flip between them. I did this for my Moonbase so it can run Taitos Space invaders part 2. Works fine. Only thing is I went further and stuck all the code into a 27256 eprom so ditched all the 2716s. Had socket issues hence why I did this.

Use a spdt switch and put 5V one side, GND other and the middle pin connect to A10. I would use a small cap and maybe a series resistor but basically it will work.

 

[Jon-A-Tron]

Nearly!

Think it is a connection issue with one or more of the adapters now. Try again tomorrow and put in an order for some turned pin sockets.

 

[andrewsm]

Looking good mate

 

[Nes4life]

Love the idea of having two games, or two different ROM-sets for the same game, on a single board just by using double capacity EPROMs and a spdt to swap a signal or two! That’s genius. If there were custom test ROMs for a particular game then you could put that in the extra space instead.

Next time I hear someone say ‘game X is a ROM-swap of game Y’ I’ll be thinking about this sort of mod.

 

[t-m]

I can't seem to find the thread, but there's an excellent one where this was done with R-type & R-type 2 on a Major Title conversion.

 

[virtvic]

I have a galaxian boot with galaxian and super galaxian via a dip switch.

 

[Jon-A-Tron]

Was about to say put it on an unused dip switch to switch a relay that switches 5v to each A10.

Certainly peaked my interest in future project.

 

[ArcadeHacker]

Great topic under discussion. My two cents:

I saw in the earlier picture that you are using a TL866 programmer, are you sure this programmer drives enough current to power the hungry old eproms? In my experience those programmers are extremely unreliable to read old eproms, never alone program them.

Good luck.

 

[Jon-A-Tron]

I believe it did program them ok. I run a comparison after each burn and before the 2nd run of burning and the read was the same as the rom file im using.

 

[Jon-A-Tron]

I've doubled up the code on the Sound EPROM. Started it up and I have the same screen as above. Gave it a credit and the game tried to play and I got a nice start-up song completely different to the Space Fever. The game didn't play though and I just got garbage on the screen.

Downloaded another rom set but the code is the same as what I already had.

Next task is to erase the EPROMs and burn the Space Fever ROMs to the 2716s. See if it just the program or my adapters. Adapter for the sound seems ok though.