Hi there, I am new to this site, and have some questions on what is allowed in terms of replacement chips for original arcade hardware to still qualify a board as valid for achieving world records.
I repair arcade circuit boards, and many of the original chips are becoming very expensive or obsolete, difficult to program without expensive and ancient 30 year old programming machines, or are no longer manufactured and impossible to find. There are modern alternatives and equivalents now, and replacement implementations that don't materially alter gameplay.
In particular, I would appreciate some clarification on the following items as to whether or not they would disqualify a submitted score:
1. Replacement of one kind of RAM with another. For example on a Williams board, replacing older, hotter 4116 with 4164, and modifying board to remove the 12v and -5v voltages that original RAM required.
2. Replacing static ram with nvram or battery backup ram for saving high scores. For example replace 6116 and onboard battery with 6116 nvram chip, such as this one: https://www.pinitech.com/products/6116_nvram.php.
3. Replacing a hard to find and program PAL chip with an easier to find GAL, for example PAL2GAL conversions found here: https://www.jammarcade.net/pal-dumps/
4. Replacing an obsolete custom chip with an alternative reproduction, such as these: (http://www.arcadeshop.com/i/948/04xx...eplacement.htm) or Caius' amazing chip work (https://www.tindie.com/stores/caiusarcade/)
5. Replacing one original TTL with another variant, for example 74LS161 with a 74S161
6. Replacing bipolar proms with alternative implementations like this: https://www.etsy.com/listing/2446337...-bi-polar-prom
7. Combining multiple original hard-to-find ROM chips into a single ROM with larger capacity, for example: http://www.paladingrp.com/brianb/boa...ingle-rom.html
8. High score save/freeplay kits that modify the program roms only slightly to add Free Play capability and/or HSS
9. Use of higher quality chips instead of original spec chips (like using a 6116 instead of a 2016 ram chip, use a z80b instead of z80a, etc.)
10. Replacement of crystal oscillators of a certain speed that can't be sourced anymore, with the next closest value crystal
<- Any other items that others can think of? ->
To illustrate the challenge for a board repairer these days, lets say that a broken board has a dead PAL chip. I could choose to replace this with a modern GAL equivalent, at $1 per chip, using an inexpensive USB programmer for $40-$50, or I can replace with an original chip at $10 per chip, and requiring an antiquated 30 year old programmer that only runs on Windows XP and costs $500 used off of ebay. For functionally the same output, the choice in terms of cost to repair is a big one, but I don't want to do that and render a board unsuitable for achieving a world record on.
On games that originally had batteries and did save high scores and/or game stats (such as Pole Position), these batteries are 30 years old, leaking onto the boards and ruining them. I would love to be able to remove these batteries and replace with a RAM chip that just persists the same data that the original RAM chip did, just without the corrosive battery in place. Some games were never built with the ability to save high scores between power ups, and those usually require some sort of ROM code modification to prevent the high score table being reset on power-up with dummy entries, so I could understand not allowing that change for those kinds of games, but it would be great to have a little more clarification specifically around what is allowed other than just it needs to be on "original hardware".
Thanks!