Funny notch in cartridge port

ral-clan · Post by **ral-clan** » Sat Jul 22, 2006 2:17 pm

Hi, I have seen on several VIC-20s that there is a small, shallow slightly semi-circular notch in the upper part of the cartridge port plastic.

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This very crude ASCII drawing is meant to show the approximate location of the notch on the cartridge port if you were viewing the VIC from the back (where the dashed lines are).

It's definitely done in-factory and not a user-mod. But I wonder why it is there???

You can just barely see it in the sixth picture from the top in this Ebay auction:

http://tinyurl.com/q7lbk

My own VIC has this notch too.

Anyone else noticed this or have an idea why it is on some VIC-20s but not others?

I can only theorize that it was put there because something C= produced which had DIP switches was banging into the top of the cart port.

Boray · Post by **Boray** » Sat Jul 22, 2006 2:28 pm

You mean in the plastic case?

ral-clan · Post by **ral-clan** » Sat Jul 22, 2006 2:30 pm

Boray wrote:You mean in the plastic case?

Yes, the notch is very shallow but it is in the VIC's plastic casing itself. In the upper shell, along the mouth of the cartridge opening.

Boray · Post by **Boray** » Sat Jul 22, 2006 2:33 pm

No, I've never seen that on a PAL vic-20...

Alan · Post by **Alan** » Sun Jul 23, 2006 9:13 am

I have two NTSC VICs. One has the 'notch' and one does not.

Funny that I've never wondered about it before, even after all these years.

Post by **bbell** » Sun Jul 23, 2006 9:38 am

Hmm.. Does anyone have a C64 breadbox model to compare the keyboard part of the case with? I can check Monday, but it seems to me that this little notch might be where the RF port is on the C64.

Perhaps Commodore started producing the keyboard part of the case using the same mould, just using a different color plastic???

Alan · Post by **Alan** » Sun Jul 23, 2006 10:01 am

bbell wrote:Hmm.. Does anyone have a C64 breadbox model to compare the keyboard part of the case with? I can check Monday, but it seems to me that this little notch might be where the RF port is on the C64.

Perhaps Commodore started producing the keyboard part of the case using the same mould, just using a different color plastic???

I don't have a "Brown Betty" C64 right now, but I've heard that the cases are actually quite different, despite their appearance. The VIC case, as I recall, is bigger than the C64 case. That would mean they were not from the same mold after all.

carlsson · Post by **carlsson** » Sun Jul 23, 2006 10:03 am

At least on the PAL breadbox C64, the RF connector fits completely in the lower plastic, so no notch in the upper half. Actually, I just assembled the top half from a breadbox 64 with the bottom half of a VIC-20 (original case, CR motherboard). It fits fairly well, a tiny bit of glitch that may occur with the original VIC top half as well.

Post by **bbell** » Sun Jul 23, 2006 10:20 am

carlsson wrote:At least on the PAL breadbox C64, the RF connector fits completely in the lower plastic, so no notch in the upper half. Actually, I just assembled the top half from a breadbox 64 with the bottom half of a VIC-20 (original case, CR motherboard). It fits fairly well, a tiny bit of glitch that may occur with the original VIC top half as well.

Hmm, that may also explain why the PAL VIC-20 doesn't have a notch.

Take a look at these two pictures (these are probably NTSC, since the site is in the US):

VIC-20 back http://www.classiccmp.org/dunfield/vic20/h/back.jpg

C64 back http://www.classiccmp.org/dunfield/c64/h/back.jpg

Looks like there is a notch on the C64 for the RF out. And it looks about the right place too!

carlsson · Post by **carlsson** » Sun Jul 23, 2006 10:24 am

So, there is a difference between the RF used in NTSC units and the one used in PAL units. This difference also resulted in different plastic moulds depending on the market. It should mean that at least a breadbox 64 can be identified PAL/NTSC on the back side.

I'll take a few comparisons pictures later.

Post by **bbell** » Sun Jul 23, 2006 10:40 am

carlsson wrote:So, there is a difference between the RF used in NTSC units and the one used in PAL units. This difference also resulted in different plastic moulds depending on the market. It should mean that at least a breadbox 64 can be identified PAL/NTSC on the back side.

I'll take a few comparisons pictures later.

Another thing I am going to check into, and you can with your units, is there is a part number moulded into the inside just above the keyboard. I am going to compare that number with a C64 and non-notched VIC's.

The VIC I have here, which has the notch, and also has grey function keys, has the number 324024-A moulded in.

Jaicen · Post by **Jaicen** » Sun Jul 23, 2006 11:31 am

I'd say that's spot on actually. If you look closely, the serial and video ports have small cutaways in the top shells also. They were absent on the early VIC20's which had flush fitting top units. The orginal VIC20 case was re-tooled when production of the C64 began, making it very slightly smaller, so my guess is that it's a late type case made from the same moulds as the C64 breadbins to save money on tooling.

ral-clan · Post by **ral-clan** » Sun Jul 23, 2006 6:58 pm

Great! Mystery solved!

That's why this forum is SUCH a great place!

Interesting to note that in the pic of those two VICs (http://www.classiccmp.org/dunfield/vic20/h/back.jpg) the top one has copper grounding tape inside and the bottom one doesn't. My VIC with the notch DOES have copper grounding tape.

Boray · Post by **Boray** » Mon Jul 24, 2006 2:19 am

Copper grounding tape!? Never seen that in a PAL vic-20...

carlsson · Post by **carlsson** » Tue Jul 25, 2006 4:55 pm

From top to bottom: C64 breadbox, VIC-20CR, VIC-20 original. All three obviously PAL units. It appears the CR has a bit more rounded cut-outs than the C64, but definitely no notch like the NTSC machines. Does the motherboard in a NTSC C64 sit higher from the case than on PAL, requiring the top half to be more rounded in the holes?