Apple II Rev 0 Motherboard Replica Project

Build your own Replica


actual Apple II number 1.299 on left, my replica on right

(rev 0 images provided by Geoff Harrison -

click here for close-up comparisons of my replica and the original rev 0

Background on the Apple II Rev 0 Replica

The first 6000 or so Apple II's sold, were equipped with what is called a revision 0 motherboard.  A number of Apple II motherboards were also sold at the same time without case, keyboard or power supply.  Most of these bare board systems were revision 0.  One of these early machines was my personal Apple II.  At some point, when the machine was on loan to a family member's business, the original rev 0 board failed.  It was repaired via replacing the motherboard with a rev 3 board.  Over the last few years, I've been working to restore the machine to original condition.  In the process, I've spent a long time looking for an appropriate Rev 0 motherboard.  

With only 6000 made,  rev 0 boards are scare and very expensive when you do see them on eBay.  I would hate to buy a complete Apple II with original Rev 0 board, only to separate the board from it's matching case, keyboard and power supply.  I needed to find either a bare board or a mismatched machine.  After a couple of years of hunting around for a stray rev 0 board, I realized that it would be quite a while before I would find what I was looking for.  I decided that I would try to build a replica of a Rev 0 motherboard for my old machine.  It seemed like it would be a fun and challenging project.  This project also would be a good way to put my machine back into a state closer to original condition.  It turned out that I was right on all counts.

What Makes a Rev 0 Board Different

Later revision motherboards were enhanced in several minor and a couple slightly more significant ways.  Many of these differences are documented on my PCB layout page.  The most significant two changes to later rev boards was the addition of a power-on reset circuit and the addition of two more colors to HI-RES graphics mode.  In the end, the power-on reset change was not significant, because all Disk II controllers also included a power-on reset circuit and most all Apple II's eventually were equipped with floppy disk drives with this reset function.   Programs that used the additional two colors of the later rev boards are almost always perfectly usable with the rev 0 board.  The net result is that rev 0 boards are almost as capable as all later revision Apple II and Apple II plus boards.

Identify an Apple II Rev 0 Motherboard at a Glance

rework area

Build Your Own Rev 0 Replica

The Saga of the Rev 0 Replica Project

Apple II Rev 0 Evolution

Apple made it's computers in batches - they made some minor tweaks to the rev 0 as new batches were made.

Rev 0 Hardware Mods

These modifications bring a rev 0 board closer to later rev hardware standards.  The instructions for these modifications were widely distributed back in the old days.  The Apple II was designed to be a platform for hobbyist, so it wasn't unusual for owners to actually apply these changes

My Apple II restoration pages

Back to Mike's Hobby Home Page