Commodore 64 PLA Replacement PLA20V8

(2 customer reviews)

$12.99$14.99

$
Qty 1 to 4 (Each) [+$14.99] $14.99
Qty 5 to 9 (Each) [+$13.99] $13.99
Qty 10 or more (Each) [+$12.99] $12.99

The PLA chip in the Commodore 64 is a common failing point today. The PLA or Programmable Logic Array is a computer chip that handles the memory map and the bank switching of the Commodore 64.

Along comes Daniël Mantione who designed this handy device to replace the original PLA chip compatible in most Commodore 64 computers.

Some frequently asked questions1,

Does Epyx Fastload work?
Yes, it works fine. The Epyx Fastload cartridge is a rather questionable design that performs analog tricks on digital lines. In order for the Epyx Fastload to work, a PLA needs to have similar analog properties and be stable at the border voltage between 0 and 1. This is the case for the GAL20V8B.

Does it work in all C64 mainboards?
Yes, except for the shortboard assy 250469 of course, because it uses a completely different type of chip. Assy 326298, 250407, 250425, 250466, 251103 (SX64), and C64 Reloaded MK1 have been tested. Assy 250441 and KU-14194HB have not been tested yet, but from what I know about these boards, I am confident about compatibility. Both PAL and NTSC tests have been done.

Can I use an alternate KERNAL?
Yes! An alternate KERNAL cartridge is a real PLA torture because a KERNAL cartridge changes the C64 mode two times within a half cycle and thus likes a responsive PLA. This has been tested both with the 1541 Ultimate II and with the Easyflash 3 and works perfectly.

Does Super-Zaxxon work?
Yes, it does work perfectly! Super-Zaxxon switches banks by means of accesses to the address lines of the C64 and as such, noise on the C64 address lines can cause undesired bank switches. This is a particular concern for EPROMs, which are known to cause switching noises on address changes. The way the GAL20V8 works, with an AND array and an OR array just like the original PLA, this kind of noise is not expected and indeed, the cartridge works perfectly.

More information about the PLA20V8 can be found here.
More information about the PLA can be found here.

1 - copied from Daniël Mantione's website.

Additional information

Weight2 oz

Share your thoughts!

4 out of 5 stars

2 reviews

Let us know what you think...

2 reviews with a 4-star rating

  1. fkokay

    PLA replacement

    fkokay (verified owner)

    Shout out to the folks at 8 Bit keep up the good work! This PLA worked well no issues! Love that you guys are helping to keep these old machines running like new!

    Upvote if this was helpful (0) Downvote if this was not helpful (0) Flag for removal

    Something wrong with this post? Thanks for letting us know. If you can point us in the right direction...

  2. One person found this helpful
    Joshua Dolan

    UPDATED: Corroded pins on GALS

    Joshua Dolan (verified owner)

    Arrived well packaged. Square pins did not fit properly in socket of PLA on my SX-64. This should be corrected and thinner legs should be used. I stupidly forced it and it got in but now the socket is noticeably more loose with a regular chip. I can put a new socket in sometime so it isn’t the end of the world since I already added sockets for the ram.

    My main issue is that it simply didn’t work. I suspected the original PLA is marginal, as the system will boot with new ram which corrected the graphic issues which pointed to at least two bad chips. Still, with the stock PLA will show odd ram sizes until a reboot and then everything is fine… almost like it needs to warm up. I figured for $15 trying a replacement wasn’t a huge deal as I wasn’t having luck online with diagnosing further without a test harness and test cartridge. This replacement gave “Out of memory in error in 0” every time it was in. I looked over GALS and noticed the legs were corroded and some looked like it was going up into the chips. With the poor fit in the socket I thought maybe there was somehow a bad connection. I tried fitting the chip to another socket I had with round legs and ended up soldering it to it to test further after checking continuity with a meter. Same result. As I don’t have another C64 at the moment to test with I had to assume it was just dead and tossed it since I didn’t want to bother with a return over $15. You win some you lose some. I will probably get another PLA replacement rather than one of these that uses GALs sometime in the future.

    UPDATE:

    8-Bit Classics reached out to me after my review. My initial review was 2 stars due to the issues. However, I am updating to say they went out of their way to look up different pins for future PLA replacements and also offered to replace mine even though I had already dumped it since I had made modifications to the pins. This is great customer service and I will definitely order here again. Changed to 4 stars on that alone. (I have also bought a C64 video cable which has been working perfectly.)

    Upvote if this was helpful (1) Downvote if this was not helpful (0) Flag for removal

    Something wrong with this post? Thanks for letting us know. If you can point us in the right direction...

×

Continue as a Guest

Shipping Policy

Thank you for visiting and shopping 8bitclassics.com. The following are the terms and conditions that constitute our shipping policy.Shipment Processing TimeAll orders are processed within 1 to 3 business days. Orders are not shipped or delivered on weekends or holidays.If we are experiencing a high volume of orders, shipments may be delayed by a few days. Please allow additional days in transit for delivery. If there will be a significant delay in shipment of your order, we will contact you via email.Shipping rates & delivery estimatesShipping charges for your order will be calculated and displayed during checkout. Options will vary based on speed of delivery including costs. Delivery delays can occasionally occur and out of our control.Shipment to P.O. boxes or APO/FPO addresses8bitclassics.com ships to addresses within the U.S., U.S. Territories, and APO/FPO/DPO addresses.Shipment confirmation & Order trackingYou will receive a Shipment Confirmation email once your order has shipped containing your tracking number(s). The tracking number will be active within 24 hours.Customs, Duties and Taxes 8bitclassics.com is not responsible for any customs and taxes applied to your order. All fees imposed during or after shipping are the responsibility of the customer (tariffs, taxes, etc.).Damages 8bitclassics.com is not liable for products damaged or lost during shipping unless it is found that the packing of the order was inadequate. If you received your order damaged, please contact the shipment carrier to file a claim.Please save all packaging materials and damaged goods before filing a claim.International Shipping PolicyWe currently ship to the following countries. Your order will be cancelled and refunded if your country is not listed here:All countries.

Refund Policy

RefundsOnce we receive your item, we will inspect it and notify you that we have received your returned item. We will immediately notify you on the status of your refund after inspecting the item. If your return is approved, we will initiate a refund to your credit card (or original method of payment).You will receive the credit within a certain amount of days, depending on your card issuer's policies.

Cancellation / Return / Exchange Policy

ReturnsYou have 14 calendar days to return an item from the date you received it. To be eligible for a return, your item must be unused and in the same condition that you received it. Your item must be in the original packaging.You will need to contact us before returning your item and it needs to have the a copy of the original receipt or invoice included. If we receive a product back without prior authorization, at our discretion, it may not be refunded and only returned to you at your expense.ShippingYou will be responsible for paying for your own shipping costs for returning your item. Shipping costs are nonrefundable. If you receive a refund, the cost of return shipping will be deducted from your refund.