Light "Blue Screen" on C64 when loading from tape, broken?

[x3r13x1z]

Hi!

I've just bought a Commodore 64 from a second-hand shop for about 7 dollars. I'ts a swedish model (I'm living in sweden) with a swedish keyboard layout (Å, Ä and Ö.

Here's two pictures of it:






If you look at the Commodore logo in the upper left corner of the computer, it's not the usual logo I've seen. The one I've seen, has three lines in different colors and it looks a little diffrent from the one in the above picture.

Anyway, when I connect it to the TV trough an RF modulator, when found on a channel, the image is very blurry, and I've got no sound at all. And when I connect via the video/sound connector on the back, the image is clear, but still not "normal" (RED/GREEN/BLUE colored dots slowly moving down the screen in a pattern).
I also got a game with the computer, "Miami Vice" made by Ocean. When I type LOAD and press enter, the screen immediately becomes light blue and also the tape reader starts. Only when I press the RUN/STOP key, I get back to the BASIC prompt.


What's wrong with the video, or s it my TV? And why does the screen become light blue when I load something?

 

[carlsson]

The C64 needs to close the screen to load programs from tape, due to timing problems. Some speed loaders managed to get around this, but the default loading routine always closes the screen so that is perfectly normal. As soon as a file is found, you get back to Basic to view the file name. When you press C= or Space, the screen will go blank again and the loading continues. If the screen keeps flashing on/off without any file name appearing, it is a sign of load error. Usually the azimuth angle on the R/W head in the tape recorder is misaligned.

It appears your C64 is one of the earliest models, usually highly sought by collectors. To obtain it for 50 SEK or whatever you paid seems like a very good deal, even if it is not in 100% working condition. I can't immediately say what causes the dot creep. Do you observe any other problems?

 

[channelmaniac]

Can you post pictures showing the creep effect? There are 3 different revisions of VIC-II chips and the earliest revision does have some spectacularly crappy looking video output. Its R5, R8, and R9 - you want the 8 or 9 for the best output.

Before you go crazy with adjusting the head on the tape deck, try cleaning the deck with some q-tips and isopropyl alcohol.

RJ

 

[x3r13x1z]

Thanks carlsson! I didn't know the screen would become light blue when I load, but after waiting about 20 seconds the prompt showed up again. I pressed C= button and the game actually loads! Thanks!

Unfortunately, my homemade video cable did broke, and I get no picture. Perhaps it's a broken wire, and it's an easy task to fix, and it will be repaired tomorrow. Tomorrow I'll also upload a picture of how the quality of the video on my TV looks like.

 

[Fallo]

The C64 needs to close the screen to load programs from tape, due to timing problems.

Yes, it turns off bit 4 (Video Disable) of $D011. The VIC-II steals some clock cycles from the CPU, so disabling it speeds up the load time. Disk fastloaders often do this as well.

It appears your C64 is one of the earliest models, usually highly sought by collectors. To obtain it for 50 SEK or whatever you paid seems like a very good deal, even if it is not in 100% working condition. I can't immediately say what causes the dot creep. Do you observe any other problems?

This is a Swedish model? I had alway heard that the early silver-logo C64s were not sold in Europe. The bad video output on these models is probably causing dot crawl. That's the reason why they used a fat text font on the C64 instead of the thin text of the PET and VIC-20.

 

[carlsson]

Now when you mention it, it looks modified with Swedish characters. You could buy those as kits and install the chips themselves, or perhaps get a serviceman to do it if you cared about warranty. Later batches came pre-modified by the importer. I'm quite sure the silver label C64s always have been available in PAL versions, but generally speaking they are rather uncommon and some C64 collectors may bid surprisingly much for a genuine one, with original keyboard and motherboard.

 

[x3r13x1z]

But is the Swedish version really worth as much as the original version? I mean, because it's a swedish version, doesn't this lower the price?

 

[carlsson]

In terms of rarity, I would think a localized version is worth equally much or more. At least among those crazy collectors who consider even modified computers to be highly collectable. But yes for a silver label one is may have no difference.