For Sale 8701 replacement: meet TOLB

eslapion

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For a few months now, a replacement for the 8701 clock generator chip used on boards 250425, 250466, 250469 and the C128 has been in preparation. Works on the C64 Reloaded MK1 too!

A prototype has now been successfully tested. I present to you The Other Little Board (or 8701 upside down...)
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Pricing is 11.50$US or 10 Euros per unit. Shipping cost is the same as with PLAnkton; shipping a small packet (up to 12 units) to the US is 8$. Shipping cost for Europe is 8 Euros, Australia and South America is 10$US.
Get a 10% discount on PLAnkton or GandALF when ordering these other products. (applies to orders of 5 units or less only - larger orders are eligible to quantity discounts)

The product is strictly shipped with anti-static protective packaging. It is covered by a 90 days money back guarantee and a 3 year replacement guarantee afterwards.

NTSC and PAL versions with appropriate frequency signals are available. Both versions cost the same price.

Main features:

  • Gold plated pins
  • 3 year guarantee
  • Onboard oscillator makes it independent from the C64 crystal - NO TUNING REQUIRED! - and easy to convert a C64 from PAL to NTSC and inversely
  • Consumes only 9mA of power (a genuine MOS 8701 consumes 25-30mA)

AVAILABLE NOW for both PAL and NTSC C64 and C128 computers!!

Please indicate your interest in this thread.

Feel free to ask all technical questions you may have.

Product photo:
102_0733.jpg

Thoroughly tested on the Commodore 128 by Ray Carlsen




 
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Preview of the board would be nice. Kinda interested on how small you got the design.
 
Preview of the board would be nice. Kinda interested on how small you got the design.
PCB is still under development. It will be 21x21mm (0.8x0.8").

I have a working (handmade, larger) prototype tested on NTSC and it works brilliantly.
 
Can you please explain the PAL - NTSC bit ? The 8701 is neither. Does this PCB have the oscillator on board ?
 
Can you please explain the PAL - NTSC bit ? The 8701 is neither. Does this PCB have the oscillator on board ?
Yes, TOLB has the oscillator on board. It doesn't use the crystal the C64 carries.

On PAL C64s, the color clock is 17.7344MHz and the dot clock is 4/9 that frequency (7.882MHz).

On NTSC C64s, the color clock is 14.31818MHz and the dot clock is 4/7 that frequency (8.18182MHz).

Generally, the 8701 uses legacy technology logic to get the crystal to resonate and then it multiplies that frequency by 4. Then a counter is used to divide back that frequency and this counter's exact limit is set by an external jumper - to 7 for NTSC and to 9 for PAL machines.

Since TOLB uses strictly modern technology, it requires its own oscillator and that makes it more resilient to external RF noise and much more stable. Just like the 8701, the only difference between PAL and NTSC TOLB setups is the oscillator and one specific connection to configure a divider by 7 or 9.

The quality and stability of the output signal is considerably better.
 
Ok, kinda interested on how it turns out then :) Mine would have been ~26mm*11mm
I designed a layout for probably the very same circuit (525-01 based, right? - as used on the C64ATX and C64XS) a while ago, but never went to the prototyping stage due to a lack of interest.
 
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Ok, kinda interested on how it turns out then :) Mine would have been ~26mm*11mm
With a board that size and format, it would likely not fit in a C128.

I wanted TOLB to fit on all Commodore computers which use the 8701.

Since I have boards 250425, 250466, 250469 and a C128, I will be able to check fit the board on all of them.

I also have a PAL 250425 so I can check for full compatibility on both architectures.

Not exactly that it matters since I have a 60MHz scope to check the quality of the output signals.

Yes, I will come up with a solution to install this new generator on both the older 250407 and 326298 boards.
 
Yes, I will come up with a solution to install this new generator on both the older 250407 and 326298 boards.
You're late to the party, Schönfeld already did that.
So ... 525-01 based or not?
I was late in the PLA party too, you know.

As for what technology is used in TOLB... pre-order one and you'll see.

I just looked at Schönfeld's 8701 replacement. Does that really fit in a C128 ?
 
I believe Jens came up with a way to use it in a C128... but IIRC it doesn't really fit. ;-)

Looking good - I actually needed an 8701 once for a broken computer, nice to have new parts that fits instead of stealing IC:s from other broken computers.
 
102_0733.jpg

The very first unit is off the assembly line, tested and working.

TOLB for NTSC C64 is available for order immediately.

Introductory pricing is 11$US or 10 Euros
 
About 24 hours after announcing the product, all 11 units available are sold out!


I am ordering a large batch of boards and components. PAL units will soon be available too.
 
One unit reserved for Axelf65 after reception of payment.

9 PAL units left.

----- -----
Another unit reserved for a buyer outiside Amibay.

8 PAL units left.

----- -----
2 units reserved for a buyer outside Amibay.

38 NTSC units left.
 
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