Hello guys,
My question is not arcade specific, but is about a ROM issue, which I have seen a good amount of support about on this forum.
I have been trying to figure out an issue for a couple days now. I have some TMS27C240 EPROMs, which I all purchased brand new. I am running the ROMs at 5V. They would run normally until the voltage at input pin A9 switches from 0 to 5V. During this event, all outputs would fluctuate thereby disturbing all of my control lines. And yes, ALL inputs are stably connected, nothing is floating.
I read in the datasheet that A9 can be driven to 12V in the signature mode(Which I am not intending to use at all). At this point I do not know whether my GQ-4x4 programmer is the culprit, and is somehow messing up the input structure while writing.
A detail that might be useful is that the I programmed the ROM so that the output is the same whether A9 is on or off. Could you please guide me on what I might be doing wrong?
Attached is the ROM's datasheet(Page and 5 mention the mention the mode using A9 at 12V). For whatever reasons I cannot attach a file to the post.
Thank you in advance for your help!
My question is not arcade specific, but is about a ROM issue, which I have seen a good amount of support about on this forum.
I have been trying to figure out an issue for a couple days now. I have some TMS27C240 EPROMs, which I all purchased brand new. I am running the ROMs at 5V. They would run normally until the voltage at input pin A9 switches from 0 to 5V. During this event, all outputs would fluctuate thereby disturbing all of my control lines. And yes, ALL inputs are stably connected, nothing is floating.
I read in the datasheet that A9 can be driven to 12V in the signature mode(Which I am not intending to use at all). At this point I do not know whether my GQ-4x4 programmer is the culprit, and is somehow messing up the input structure while writing.
A detail that might be useful is that the I programmed the ROM so that the output is the same whether A9 is on or off. Could you please guide me on what I might be doing wrong?
Attached is the ROM's datasheet(Page and 5 mention the mention the mode using A9 at 12V). For whatever reasons I cannot attach a file to the post.
Thank you in advance for your help!