ScuzzBlog: Diaries June 2020

Entry 16th June 2020: Post 1: VC 20 - Not as lucky as with the VIC.

VC 20 - Not as lucky as with the VIC.

I really don't have much luck with the VC 20. For years I had these
three VC 20's propped against the wall with busted stickers on the
base. The one even states it has been that way since 2005. Not sure
why given the success rate I have with the VIC 20.

From the two machines I show today and the one I will feature tomorrow
I get a variety of screen displays from a grey screen to static and
even garbled letters. The fault I fear lies with the video chip
given that the others seems to be warming nicely. I really don't

Anyhoo I decided to take a photographic journey with the first of
the broken ones and just a couple of snapshots of the other. The
third broken one, wasn't actually broken the last time I reviewed
the computer so I have taken her back to the bench to check. More on
that in the following blog.

The VIC 20 ( or VC 20 in Germany ) gets its name from the video chip
or MOS Technology VIC. The chip was designed originally for use with
high end machines and games consoles. Sadly Commodore couldn't find
a market for the chip and so Al Charpentier's 1977 chip found its
way into the VIC 20. Al also helped Robert Yannes in the early days
build the MicroPET, a kinda unofficial home project which eventually
became a prototype and featured at CES.

Interestingly the VIC 20 was code named Vixen and although has its
origins in the prototype made by Yannes was more honest to the PET
The rest is history as they say as the next decade would see Commodore
lead the world in producing home computers which kinda started with
this little beast.

VIC 20 made by Commodore in the USA May 1981 using CBM BASIC V2.
The CPU or processor was a Commodore Semiconductor Group 6502A and
ran at 1.0227 MHz. The VIC 20 uses the VIC-I (6560) co-processor for
both sound and graphics.

The VIC or Video Interface Chip MOS Technology 6560 was primarily
designed for CRT terminals, biomedical monitors, control systems,
arcade and home video games consoles. Interestingly the chip is
normally socketed but should not be used on early C64 boards as the
voltages would result in a burn out.

The VC 20 (VIC 20) does not have a built in RF modulator and so
needs the little external black or silver box. Also note that the
VC 20 uses the standard C64 power connection, whilst the VIC 20 has
a more square double header socket. As to why ? Who knows.

One problem with the VIC is the fuse and power socket. A poor 
connection at either can prevent the machine from functioning. The
suggestion is ensure that the fuse is not loose and that the power
fits 'tight' in the connector. Sometimes crimping the power connector
to ensure a tight fit helps.

VC 20 - Not as lucky as with the VIC.

Screen changes on power on. Encouraging.

2nd VC-20

Has been broken since she arrived in 2005.

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Last updated 16th June 2020

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