I posted about this a while back ago but I want to jump back on the horse and try to get the 2+ working again. Here's where I stand:
1. I used an old cut up 300 watt PC power supply because my 2+ didn't have one when I got it
2. The first two rows of RAM have 8116s instead of 4116s and the 3rd row has another kind. I don't remember what they are off the top of my head but they aren't 4116s.
3. Upon stripped down boot up, all I get is a screen full of ??@@??@@. No beep, no prompt, just ??@@. If I remove all the RAM, I get all ???? (No @s).
4. All voltages on the RAM pins check OK, reset pin on the CPU is about 2.37v but I don't think it would keep the system from booting. Or will it?
5. Keyboard input does nothing. This includes CTR+(other keys)
6. The 6502 and ROMs get warm after a few minutes of being on. Not super hot, just warm as if it were working.
I think that's all. If there's anything else to check, please let me know. I have a multimeter and ocilliscope. I'm not 100% sure how to use a scope and I don't have a probe so i'm not sure if the scope will be useful.
One site said it could be either RAM, databus, or addressing bus. I know I need to get a row of working 4116s but is there anything else that might be the issue? Just to save rounds of ordering chips.
Let's get 'er going!