Jump to content

Williams blitting and a non-emulated multi-game cab


Recommended Posts

This site has some interesting tidbits about Williams arcade machines, including a multi-game cabinet that runs real (not emulated) versions of Joust, Sinistar, Robotron, Splat, and Bubbles.




Why do this? Well at the time (and possibly today as well) there were slight differences in blitter operations between the real machines and the emulated versions. Here's an excerpt:


In older versions of MAME and in several xx-in-one boards, blits happen pretty much instantaneously, unlike the real games where the Special Chips have a maximum throughput of 1 MB/second (not counting the time it takes to write to the registers to start the blit). This results in games that appear normal at the beginning levels, but become much harder at the later levels. Robotron can have so many enemies on screen at once that all cannot be moved in one video frame. So the game moves as many as possible, then moves the rest in the next frame. With an "instantaneous blitter", all the enemies can be moved in one video frame, making the game play much faster.




About 13% of the blits had different results in MAME than on the real game, and about 11% of the blits took a different amount of time in MAME than on the real game. I'm sure that these blits represent a very small proportion of blits done in actual game play, but they may still contribute to game play anomalies.




Defender and Stargate are included in the cabinet too, although those two don't actually implement blitter code.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...