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I'm about to swap the bad 9316b roms out on my SID for 2716 eproms. There is a post here on klov saying I have to remove the S2 jumper to use the 2716 eproms, is that correct?
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Yes the standard 2716.I believe S2 if for pin 21 of the sockets. That's Vpp on a 2716 (I'm assuming you're not talking about a TMS2716).
Conventionally, Vpp is connected to Vcc (+5V) for normal (non-programming) operation.
I'm not sure what happens if Vpp is left floating (unconnected).
Ha! Funny, I had the almost the same comment to the almost the same question 11 years ago.Yes the standard 2716.
This is the post I'm referring to BTW.
Tech: Space Invader rom strapping info
Here are some pictures that show the strappings for different roms on space invaders and deluxe. Most you will come across will be strapped for 9316 mask proms. To use 2716 just remove S2. Chances are you will never strap a board for TMS2716 but here is a pic just in case.forums.arcade-museum.com
Gotcha thanks! I was getting mixed signals lol. I wonder why though, on the post from @TSB, s2 has a red line also drawn to com/ground as well?Ha! Funny, I had the almost the same comment to the almost the same question 11 years ago.
Read through that whole thread. Especially check out post #19 by @TSB where he posts a picture. Some of the labels are a little confusing (if the label refers to the nearby point or the trace underneath), but the red lines appear to show two options for properly connecting S2 (PROM pins 21) to +5V.
Don't feel bad. EPROM strapping on Midway 8080 boards is a bit of a mess. They designed those things to be strapped to support a huge list of memory devices; different types and sizes.
Gotcha thanks! I was getting mixed signals lol. I wonder why though, on the post from @TSB, s2 has a red line also drawn to com/ground as well?
Ok gotcha, thank you very much for all of your help! I see what it's saying now, S2 simply needs 5v, it's just showing the closer 5v trace right next to it as well as a 5v solder pad right next to S3. This also matches with this info below that I found on another website.Yeah, that part of the confusing labels I was referring to. I believe that the trace just above the S2 jumper point is a +5V trace (as he has it labeled to the right). The confusing label of "COM" which appears to be on the same trace (to the left) I believe refers instead to the point directly below it (the left end of the blue line). That's probably where your S2 jumper was connected for 9316B strapping.
That trace (just above the S2 point) was never intended (by the PCB designer) as a jumper point. But it's nearby, and many people have used it as a convenient place to connect S2 to +5V. Another options is the one down below (the other red line in TSB's picture). I never was fond of that line, because I'm worried about the jumper wire getting bent and shorting with the A10/p19 jumper. Yet another option (not mentioned in that other thread) is to go to the +5 up by S1.
Any source of +5 should work fine. And leaving it floating may work OK too (reliably or not); I never saw Riptor follow up about that. But the ones I've re-strapped, I connected S2 to +5V (I used a solder blob to the nearby trace).