Commodore_PET wrote:
So I have been able to measure the voltages on at the RAM chips, Ive found following Voltages present in following Pins:
Pin 1: -5.20 V
Pin 9: 4.95 V
Pin 8: 11.71V
Pin 16: Ground
Those voltages are all okay.
Commodore_PET wrote:
Having the machine on for the 15 or so minutes that it took me to make these readings i noticed the RAM chips were getting noticeably warm, so I checked all the other chips too and the ROM chips were getting very toasty so i turned the machine off again.
It’s normal for that type (MK4116N and NEC PD416) of DRAM chip to run warm.
I don’t have a PET, so don’t know about the type of ROM chips used. However, if you can’t touch one with your finger, even briefly because it is too hot, then it may be faulty.
Commodore_PET wrote:
@Martin A: it might be a RAM upgrade, or probably is because the type of chip in the second memory bank is of the type NEC PD416 while the first memory bank has MK4116N chips.
The MK4116N and NEC PD416 are equivalents to each other. Both are 16k bit DRAM chips (often described as 1 x 16384), each chip provides one data in and one data out pin, hence to store a byte for a 8 bit microprocessor like the 6502 you need eight of these chips (8 x 16k bits = 16k bytes).
Using you multimeter on the 20V DC range (or equivalent), can you please test pin 40 (/RESET) on the 6502. Also pins 4 (/IRQ), 6 (/NMI) and 7 (Sync).
Mark