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Old 13 April 2014, 19:56   #1221
Join Date: Jun 2010
Location: out in the wild
Posts: 1,129
Originally Posted by roy bates View Post
personally after over 20 years of using these im not really all that concerned about energy efficiency,although the more important problem of the faulty power supply taking out half the board is a problem on the original...
Don't forget that the heavy PSU needs to be carried if you're going to a party (the true C64 fan knows that 2014 is an X-year - see ). There's quite a difference between over 1.5kg for the brick and around 140g for the 12V wall PSU.

Originally Posted by roy bates View Post
is there a reason it cant be shipped with a cpu and sid? or do you think they are hard to get.considering your using the original vic ii memory and cia's
I just don't have enough CPUs and SIDs: Practically no SIDs to sell, and only less than 10 CPUs that I'd part with. All the other chips are in stock for the low quantity I'm planning. The price will drop for those who want the board with even fewer chips. I'm hoping for my new shop system to easily cover this (yes, that darn Ondango shop system will go this summer).

Originally Posted by roy bates View Post
maybe you could explain this "bug" that makes the original inferior to the one you remade,does it effect the visual appearance on screen in some way,that an everyday user would appreciate?
VSP is an effect where scrolling a picture "into all directions" is possible on the C64, as if you're moving a bitplane pointer on the Amiga. With normal hardware capabilities, the C64 can only scroll it's picture by a few pixels before the CPU has to copy the whole screen data, so with VSP, you can make high-speed scrolling games. Mayhem in Monsterland makes use of this effect. See [ Show youtube player ] - Advance Video to about 5 minutes to see the *extremely* fast scrolling. And it crashes on a good share of C64's, leaving a characteristic crash pattern distributed over the whole 64k memory.

Up until about a year ago, the reasons for this were not explained. The man who finally got the answer was Tommi Lempinen, who has pulled me aside at Revision 2011 and Revision 2012 for some multiple-hour talks about possible reasons. After he explained all his findings, I was confinced that it's a memory timing failure, which Tommi has proven with measurements that he showed me at Revision 2013. These measurements show that the address hold time for the RAS cycle is violated on some VIC-II chips. I guess we both deserve credit for explaining the bug, but Tommi has actually proven it. I only pushed him into the right direction.

Urban legend for almost two decades was that the VSP bug is caused by missed refresh cycles. Tommi has proven that it's an address hold time bug.

Originally Posted by DonAmiga View Post
Will this be available for pre-order through the retail like amigakit or just your own store?
Originally Posted by dJOS View Post
Jens, is there any chance of you selling direct to remove "middle men" margins and make it more affordable?
The current plan is to only sell it through my own (new-to-be-installed) shop system.

Originally Posted by Zetr0 View Post
Well after looking at the product, components and PCB manufacture you would be looking at sub $12 per unit for 25+ units. Obviously manufactured in China / Asia
Sigh - are you really judging a product price by the price of components? Labour, development cost and financing, possible warranty returns, customer support, testing is not in your calculation?

Originally Posted by Zetr0 View Post
At 149 this is insane!

How many working C64's can I buy for this price!? A quick scan on eBay says nearly half a dozen!
...and maybe you can even buy enough to have one that will not show the VSP bug. It's a game of chances, like buying a used car: You save a lot of money, and you have no warranty.

Originally Posted by ajk View Post
As you probably well know, the video output on the original C64s can vary quite a bit, with all kinds of interference or signal leakage often seen on the s-video. Does your new board design improve on this?
There's widely known circuits that allow modulating the AEC and Phi2 signals on the Luma and Croma lines, so any vertical lines (Phi2 luma drop) and horizontal lines (badline luma drop) can be minimized. I have also implemented these on the C64 Reloaded. This part of the circuit is not yet tested on the first prototype board that is pictured here, because I didn't like the "stock" picture quality of this first prototype. The next prototype will have more filtering for the analogue voltages, even separated for SID and VIC, and if that's closer to what I like, I'll start verifying the luma compensation circuits.

Originally Posted by demolition View Post
Does it have to be that advanced? I mean HDMI supports both 50 Hz and 60 Hz modes, so an ADC with a small FPGA to convert its output to HDMI format with simple pixel and line quadrupling should be less complicated. The output from the C64 is always progressive right? Then it would just output 50 Hz in PAL mode and 60 Hz in NTSC mode. That would also mean smooth motion and low latency. Of course then someone would want scanlines, blurring filters etc. which would ruin the simplicity.
Chameleon is the answer to "where do you stop when you've started improving?" - People like us don't stop, we want to go all the way. Since you need to collect a lot of information inside a relatively huge FPGA, adding "one more feature" is not a big deal on the component side, and that has lead to the Chameleon as it is right now: Packed full with features that would easily cost 1300,- EUR if you'd buy them in separate hardware products.

Besides, HDMI only accepts 50 and 60Hz in very specific resolutions that need to be generated by scaling first. You don't get around the FPGA, even if you're only talking colour space conversion (HDMI wants to see RGB, but the VIC-II generates YUV, where UV is combined in the chroma signal). Another problem is that the signals already come out of the chip in analogue format, so you need to convert them to digital before you can do anything with them. In essence, you'd be adding a product that would be better-suited as a stand-alone product, so it can also be used with other Commodore computers.

Originally Posted by Turran View Post
Not in theory, but in practice. If I have a broken C64 and want a new motherboard, do I pay 10-20 for an old used one and get parts to spare or do I buy a new motherboard for 150. Sure, it will be nice with a new one, but they do the exact same thing, so in practice there is no difference between them.
"in practise", they don't exactly do the same thing. Even today, there's C64's being used in industrial applications (that dental-replacement test machine in Switzerland and the hotel owner from Argentina probably being the most popular examples), and here's where you're happy to pay a little extra if you have someone who is *responsible* for what he delivers, so we're not only talking about a hobby/enthusiast thing. Besides, I won't be able to deliver masses of these boards, so it's good that some people "pass" on this one.

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