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burning an eprom, missing something


Osgeld
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I made a little rom cart to test some of my program fiddling, but I cant get it past the atari screen.

 

its using a intel D27256-3 32k eprom and its wired up like this. I checked all my wiring like 3 times, I have tried a rom I compiled and is working in emulation, also tried robotron, kung fu master, and beef drop.

 

I am using a Tl866A "minipro" programmer, and every single time I can get to the atari 7800 startup screen, then it switches to a screen of garbage, sometimes a barf sound, then the whole system locks. I can instantly take the cart out and run any production 7800 game

 

I have been searching but not finding much, thanks

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In my (mis)adventures with the 7800 32K games the inverter was the culprit (on /OE, pin 22), maybe you have an issue there.

My real Robotron cart (which is ROM) also needs a 100Ohm resistor series on VCC, without it it locks, never understood why.

Finally maybe your EPROM is active high? Try removing the inverter and see what happens, I doubt it.

 

Asking the obvious but you did verify the content after programming it, there's a verify on the TL866? Maybe you have a faulty EPROM halfway thru.

 

As Mitch already stated you should use:

https://atarihq.com/danb/7800cart/C024926.pdf

(aside A15 it is identical though and if I remember you do need the inverter if you use an EPROM, as the ROM masks were instead active on OE high)

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Is there a reason you are using Activision bankswitching instead of Atari Bankswitching? For that matter why are you bankswicthing at all with a 32K EPROM?

 

Mitch

 

Its not bankswitched, its just got an inverter on OE, just like if one were to patch up an atari cart

 

In my (mis)adventures with the 7800 32K games the inverter was the culprit (on /OE, pin 22), maybe you have an issue there.

My real Robotron cart (which is ROM) also needs a 100Ohm resistor series on VCC, without it it locks, never understood why.

Finally maybe your EPROM is active high? Try removing the inverter and see what happens, I doubt it.

 

Asking the obvious but you did verify the content after programming it, there's a verify on the TL866? Maybe you have a faulty EPROM halfway thru.

 

As Mitch already stated you should use:

https://atarihq.com/danb/7800cart/C024926.pdf

(aside A15 it is identical though and if I remember you do need the inverter if you use an EPROM, as the ROM masks were instead active on OE high)

 

I will try the resistor for goggles, I have tried multiple in/out's on a couple LS04's with the same result ... eprom is active low, if I go direct to a15 I wont even get a logo

 

and yea that is identical to the activision setup minus the inverter

There is also the signing issue, unless you run a hacked BIOS.

 

I checked all the files though the signing program, it reported back OK on all of them

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