J-CIA - MOS 6526 / 8521 / (8520) FPGA REPLACEMENT

J-CIA64

Modern spare part for Commodore 64, Commodore 128, SX-64 and 1570/1571 -drives

FPGA based replacement for MOS 6526 & 8521 CIA chips

Complete logic and all features of the original IC's implemented

All diagnostic & software tests passed 100%, including all tests in Wolfgang Lorenz's test suite and Vice-project's CIA-tests.

[Vice's ciaports-tests may show partly incorrect results, but then again, original cias show variable results too.]

Hundreds of demos and games already tested, no known compatibility issues currently

Physically about the same size as the original CIAs

Lots of hardware tested and found to be compatible including (but not limited to) WifiModem, Ultimate-II+, SD2IEC, TapeCart, 1351-mouse

Tested with all C64 mainboard revisions, SX-64 and with EVO64 mainboard, Commodore 128 (including CP/M and disk drive burst-mode) and 1570 & 1571.

Works in 1 MHz and 2 MHz modes.

This 6526/8521 version has been tested to work on a 1581 drive too by a betatester, but full compatibility cannot be guaranteed.

(8520 Amiga -version would be the correct one for 1581)

 

This "J-CIA64" -version is not compatible with Amiga / 8520-CIA and cannot be later converted or upgraded to be.

Amiga -compatible version will be a separate product that will be released later.

Changing mode between 8521 "new" and 6526 "old" CIA:

Mode between new (8521) and old (6526) cia type can be changed

with a solder jumper on the underside of J-CIA64

"New" 8521 mode is default and 6526-mode can be enabled by soldering

two pads together as in the right on the image below:

Usually, the mode doesn't need to be changed,

most sofware and hardware are designed to work with both versions.

Installation

Although J-CIA could be soldered directly to mainboard, using IC sockets is highly recommended.

Pins on J-CIA are gold plated round pins, which will work with all kinds of sockets, but

the pins are a bit thicker than original IC-pins, which may cause slight stress to some leaf-type

sockets. This is a the same with all reproduction IC's with turned pins.

Be careful when pressing the J-CIA into a socket and make sure it is aligned properly and

pressed down evenly to avoid bending or breaking of pins.

 

J-CIA orientation: PIN 1 is marked with a number 1 on PCB. That should match PIN 1 position on mainboard.

There is also a half circle marked on the top of the J-CIA. This relates to the notch on original IC's and the notch on IC-sockets

On a C64 CIA PIN 1 is located on top left of the both CIA -locations.

On a C128 the other CIA position is "upside-down", so be careful installing a new CIA the correct way

 

Original RF-shields may require insulating, modifications or even removing.

Before turning on the power, check that the RF-shield metal does not touch J-CIA(s).

Disclaimer

J-CIA / J-CIA64 reproduces the functionality of the original MOS CIA's

Because it's a reproduction, it cannot be ever fully like the original.

Logic aims to be exactly like the original, but there may be differences that have not been found yet.

Electrically J-CIA is "close enough" to the original CIA, but it is not exactly the same.

Although tested with a lot of hardware and software, compatibility with all hardware and software cannot be guaranteed.

nstalling the J-CIA64 requires delicate handling and taking the proper precautions to prevent antistatic discharges.

The seller or manufacturer cannot be held responsible for any possible damage this product may cause to your

equipment due to incorrect installation or mishandling of the product.

More info

J-CIAs tested on Retro Recipes youtube -channel: https://youtu.be/EL2HVRtjuIg

J-CIAs were tested by We're all geeks: https://wereallgeeks.wordpress.com/2023/08/09/jcia64/

 

Where to buy?

J-CIA is available at the following online shops:

 

Run Stop Re-Store on Retro8bitshop is one of the biggest Commodore 64 spare parts depot in the world,

with huge stocks of New Old Stock components, as well as modern alternatives, with fast shipping and top-notch service.

J-CIA at their web shop: https://retro8bitshop.com/product/j-cia64/

Run Stop Re-Store ships internationally!

 

Retrospective shop:

https://retrospective.shop/j-cia/ Retrospective shop ships internationally too!

 

Swiss customers can buy J-CIA's at Digital Retro web shop at https://shop.digitalretro.ch/

Digital Retro ships only to Switzerland.

 

Finnish customers can buy J-CIA's at Am-Mek web shop at https://shop.am-mek.fi/

Am-Mek ships only to Finland.