Williams Rom Chips- Technical Details

Yellowdog from KLOV-

  • If you want a new set of Robotron ROMs burned, Steph is your man (www.hobbyroms.com).
  • The Blue ROMs were the last set burned by Williams (Blue refers to the label color). They have the latest “official” bug fixes.
  • The Orange ROMs were the second release. They were never released with orange labels. The labels were yellow but somebody ran a red marker across them and over time it faded to orange. The B was penciled on because they didn’t want to wait for another run of the stickers from the printer, plus they had stacks of the A labels.
  • There are Robotron ROMs that were burned on type A ROMs (2532), but they were very rare. Williams switched to 2732s because they were unable to get 2532s in quantity (did Pacman or Ms Pacman use 2532’s?).
  • As Steph said the ROM cards can be strapped either way.
  • Most of the ‘ROM’s are actually EPROMs (Erasable Programmable Read Only Memory). If you pull the labels off they can be erased and reprogrammed. Most of the time.

Steph from KLOV-

  • The “A” or “B” designation was for the TYPE of eproms
  • “A” was for 2532 eproms “B” was for 2732 eproms
  • The rom board can be jumpered for either type.
  • “B” eproms are FAR more common (10-1) than “A”.
  • In fact, I’ve only ever seen “A” eproms on one Joust rom board.
    I’m guessing “A” eproms “may” have been used in early runs, but since 2732 eproms (B) were likely cheaper and more abundant, they became standard in later runs.
    Roms and cool Rom hacks, plus burning services available at
    E-mail Steph at info@hobbyroms.com


  • Orange roms will default to difficulty 5, whereas Blue roms will default to difficulty 3.
  • 2732 Roms are also available from- http://www.epromman.com/
  • If you want to see the program that goes on roms, open up a robotron.zip from MAME- Each ROM file corresponds to an EPROM on the game- numbers 1-9 are the same The MAME files A, B and C correspond to EPROMs 10, 11 and 12.
  • More info about the Digital Eclipse patch HERE

The “Steve Ritchie” Romset-

  • Larry DeMar programmed a unique Robotron romset for Steve’s Robotron which listed the names of his family as the family members in the game.  The machine was sold to a private collector in the SW US via craigslist.
  • Larry, Dec 2013- Indeed, I did that mod for Steve’s game. I just ran across the patch for it when I was
    scrounging around the Robotron code.

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