I have recreated the original Asteroids arcade PCB in KiCad. Errors in the original schematic have been fixed and any patch wires have been included in the board. Other than the patch wire fixes, the PCB is a faithful recreation of the Revision 2 circuit board it was based on. Below are the project files and screenshots.
I decided to have some boards manufactured and I assembled some of them and made a working recreation of the Asteroids game PCB! The images are below.
IC Adapter PCBs
Notice that IC C8 and M6 are on adapter boards. This is because these ICs are no longer available. C8 is the vector state machine ROM. I made an adapter so an M2716 EPROM chip could be used in its place. The original M6 IC was an LS83. The adapter board allows an HC285 IC to be used in its place. Below are closeups of the adapter boards.
Finally, In order to get the video output to work properly, I had to make some changes to the components in the analog section of the PCB. The changes are highlighted in the image below.
The SHCON signal was not pulling low enough to fully turn off the sample and hold analog switches. Because of this, R115 was changed from the original 330 Ohm resistor to a 220 Ohm resistor. This allowed the negative voltage swing to go from -2 volts to -6 volts.
The DAC settling time was taking too long and causing artifacts to appear on the display. To reduce the settling time, Capacitors C97 and C105 were replaced with 24K Ohm resistors.
Although not shown in the image above, IC C4 was replaced with an LS164 due to lack of availability.
That’s it! The PCB works and now I have a perfect recreation of the original Asteroids video game. Stay tuned! I may decide to sell them if I can make them for a reasonable price…