Re: Building a 6502 peripheral - timing

From: Mia Magnusson <mia_at_plea.se>
Date: Wed, 21 Mar 2018 00:11:21 +0100
Message-ID: <20180321001121.000017ab@plea.se>
Den Tue, 20 Mar 2018 09:58:50 +0100 skrev Hegedűs István
<hegedusis@t-online.hu>:
> I had 7406 chip problems causing the black screens. One in a VIC20
> and one in a Plus4.
> I think those like to die also, so it always worth to check them.

At least in VIC 20 this seems to be a common fault but the reason can be
that someone connected a "4 out of 7" pin DIN power supply (C64, VIC-20
CR) to the IEC serial connector.

VIC-20 runs the 1MHz clock from VIC to the rest of the computer through
the same 7406 that also drives outputs on the IEC bus.

With no clock to the CPU the VIC chip will start in a mode that gives a
black screen (with correct syncs and for PAL a correct color burst).

-- 
(\_/) Copy the bunny to your mails to help
(O.o) him achieve world domination.
(> <) Come join the dark side.
/_|_\ We have cookies.
Received on 2018-03-21 01:00:02

Archive generated by hypermail 2.2.0.