Is it at all possible?

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boelle
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Is it at all possible?

Post by boelle »

Hi

I got hold of an eagle schematic for the C64

http://www.baltissen.org/images/c64.png
http://www.baltissen.org/zip/c64.zip

First of all i wonder what board rev matches this schematic? and if there are a high res scan "out there" i could use for initial component placement

Next would part are ABSOLUTE not to be found no where? ie it would be insane to look if it cant be found anyways, but my goal was to do a BOM and board layout

Next, how much use would the work be in general?


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eslapion
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Re: Is it at all possible?

Post by eslapion »

boelle wrote: Mon Feb 13, 2017 10:48 pmFirst of all i wonder what board rev matches this schematic? and if there are a high res scan "out there" i could use for initial component placement
Looking at the schematic, the method employed to generate the color and dot clock signals are the same employed on early 326298 boards but the video output connector has separate Luma/chroma signals like board 250407.

Boards 250425 and 250466 used the custom chip 8701 for which I created a substitute.
Next would part are ABSOLUTE not to be found no where? ie it would be insane to look if it cant be found anyways, but my goal was to do a BOM and board layout
Other than the MOS 65XX chips made by Commodore, AFAIK, all semiconductors and standard electronic components used in the C64 are still available or possible to replicate. The 8701 was still a problem... until last week.
Next, how much use would the work be in general?
Ask Schönfeld how much time he needed to create the C64 reloaded... it's really a 250466 with a bit of rework to combine all the ROMs in one chip and all discreet logic ICs turned surface mount.
Wealth, like happiness, is never attained directly. It comes as a by-product of providing a useful service. -Harland D. Sanders
boelle
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Re: Is it at all possible?

Post by boelle »

With use i mean how much value it would be to others?

My plan is initial to get a BOM made and share that public. I got most of it down only missing the chips
And i also got the schematic in eagle and just need to cross verify everything

Then i will pay a one month license for eagle and do a replica board. With some clever thinking i found that what i have to work with is PCB 326298-01 and Schematic 326106. So pretty much as original as it can be
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eslapion
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Re: Is it at all possible?

Post by eslapion »

boelle wrote: Tue Feb 14, 2017 9:09 pmWith use i mean how much value it would be to others?
That's a question for a marketing analyst...
With some clever thinking i found that what i have to work with is PCB 326298-01 and Schematic 326106. So pretty much as original as it can be
Board 326298 is interesting because it is the very first C64 board on the market but it has several drawbacks.

The first obvious one is that it doesn't provide separate video which really sucks as you can't really get the full image resolution and quality a VIC-II can provide on composite signal.

The second one I can think of is the absence of an adequate RC filter on the CASRAM line which makes it incredibly sensitive with respect to PLA timing.

Many PLA substitutes work perfectly well on boards 250425 and 250466 but not on board 326298 because this filter is missing.

I think board 250466 is the best.
Wealth, like happiness, is never attained directly. It comes as a by-product of providing a useful service. -Harland D. Sanders
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Re: Is it at all possible?

Post by boelle »

i might expand the work later

for now i just wanted to start somewhere
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eslapion
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Re: Is it at all possible?

Post by eslapion »

boelle wrote: Wed Feb 15, 2017 2:16 pmi might expand the work later

for now i just wanted to start somewhere
"expand" is the magic word here.

Jens Schönfeld based his C64 Reloaded on board 250466 because it is the version of the Commodore 64 with the fewest number of components, except perhaps for the C64c 250469 which has a larger and incompletely documented PLA.
Wealth, like happiness, is never attained directly. It comes as a by-product of providing a useful service. -Harland D. Sanders
boelle
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Re: Is it at all possible?

Post by boelle »

well i got the schematic down, now i just need a 326298-01 to replicate. it does not even matter what state the board is in. hell all components can be taken out. would even make my job more easy as i would take every single component out anyway so i can use it as a template when doing the tracks in eagle
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