Re: C64 reset timing

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Mon, 25 Jan 2021 21:10:34 +0100 Message-ID: <d6fa1e70-20b7-fb10-8414-091e7c8743a3_at_laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

On 1/25/21 8:46 PM, silverdr_at_wfmh.org.pl wrote:
> When testing BeamRacer prototypes on as many different C64 / SX64 boards as possible I remember encountering a problem with one machine, which we had to take into account and work around. The root issue with that particular board was that upon power-up the _RST (reset) line was not asserted for some prolonged time but became inactive (almost?) immediately once VCC stabilised. This didn't seem to affect the way the machine worked and I probably wouldn't notice it at all if it wasn't causing issues with our add-on. While now I am yet to find that particular machine back and analyse it thoroughly, I am wondering that's something, which could be described as a common failure or feature? Has any of you in the know encountered anything similar?

Depends on the board, the reset circuits differ between boards. But a 
very fast Reset means that a capacitor has lost capacity or the resistor 
it charges through has lost resistance. On the 250407 this is a 
combination of 100nF and 1 MOhm for example.

  Gerrit