The 8702 clock generator is a replacement for the MOS Technology 7701 and 8701 clock generators that are used in the Commodore 64 and Commodore 128 computers. It is based on the Renesas GreenPAK SLG46536. The 8702 clock generator is a drop-in replacement for the 7701/8701 in your Commodore 64 or 128. Simply remove the old chip, place the 8702, and the computer will work.

In addition, has a few additional features that can be of interrest to designers of C64 clone mainboards:

• The 8702 implements the RAS/CAS generator that is present on the 8701 but not on many other replacements.
• The 8702 has a smart RESET circuit that monitors the voltage of the Commodore 64 and allows for a reset button to be connected to the 8702.
• The 8702 has a circuit that handles the RESTORE key on the Commodore 64 mainboard.

In other words, the 8702 can replace the NE556 timer chip and all components around it on Commodore 64 mainboards. This simplifies the design of a Commodore 64 mainboard and reduces the number of unique parts and thus makes construction of modern clones easier.

There exist many other replacements of the 7701/8701 clock generator and the 8702 does not claim to be a better solution than the existing replacements. However, the majority of the existing replacements are based on the ICS525-01 clock chip from Renesas. This chip is no longer beging manufactured and it is likely that many replacements will stop being available within the near future.

The 8702 clock generator attempts to look forward and is based on the GreenPAK SLG46536, which is not only in full production, but is also a low-cost chip. Therefore the 8702 tries to have a good Commodore 64 clock chip available for a long time at a low cost.

The 8702 clock generator is compatible with both PAL and NTSC Commodore 64 mainboards. Commodore 64 mainboards that use the 8701 are the assy 250425, 250466 and 250469. In addition, all Commodore 128 mainboards use the 8701. Commodore mainboards assy 326298, 250407 or KU-14194HB use a different clock circuit based on the Motorola MC4044P.

The 8702 clock generator is an ideal solution if you need to replace a broken 7701 or 8701 chip on your Commodore 64/128 mainboard, or a good solution if you are doing a new Commodore 64 build on a modern clone mainboard.

If you want to build this project:

• Purchase this PCB from PCBWay
• Purchase the components
• Get yourself a GreenPAK programmer. Suitable programmers are the SLG4DVKLITE and SLG4DVKADV with a suitable socket adapter for the SLG46536V. Note that if you buy a socket adapter for the SLG46536V, it will include chips, so you no longer need to purchase the chips separately.
• Program the design file for the 8702 into the SLG46536V. The software you need is the Renesas Go Configure Software Hub.
• Solder everything together.

Please read more about the 8702 clock generator on its web page. You can also download the design file for the SLG46536 there that you will need to program the chip.