Hello, since everyone says the 8501 CPU has a high failure rate due to overheating, I did some measurements by lifting Pin 5 (Vcc) from the socket and using an Amp meter set to 200mA between it and +5V to see how much power it really needs. The measurements were taken with the system sitting idle at the welcome screen after waiting for about 30 secs for the chip to warm up (power consumption goes down). The results: 7501R1 datecode 2684: 85mA 8501R1 datecode 4184: 108mA 8501R4 datecode 4986: 109mA To compare against a CPU that is not known for a high failure rate: 6510 datecode 2784: 96mA The surprise was that the 7501 uses about 23mA less than the 8501, I would have expected the opposite. In any way, even the 109mA translate to at most 545mW the chip has to dissipate. That's well inside what a 40pin DIP IC can handle, it's nothing that would cause it to overheat, the 6569-VIC in a C64 runs much hotter. Unless there is a hotspot on the 8501, overheating can't be the reason for the high failure rate of this CPU. Still, a heatsink will cause the die to run cooler and slow down whatever causes the failure. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2012-02-12 18:00:05
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