Subject: Re: [stella] Combat REFPx mystery From: Glenn Saunders <mos6507@xxxxxxxxxxx> Date: Tue, 23 Aug 2005 04:43:28 -0400 |
At 12:39 AM 8/23/2005, you wrote: >Glenn wrote: > > But not only that, it's also still necessary to reflect the sprite, > like to > > have the car point left instead of right. > >Probably they yet didn't fully understand the hardware back then? Sure, they didn't understand what the hardware was capable of doing beyond the original features. But they knew what all the built-in features were, and they do use the reflection, but only in a seemingly frivolous way, like they didn't see the obvious way it could be used to optimize things. The number of instructions it looks like Indy 500 is having to run through to determine whether to turn on REFPx he could have just stored one more frame of graphics because it looks like he only really _has_ to turn it on when the car has to face left. You'd think it would have dawned on him to think of the graphics in terms of left-right symmetry if he's thinking about the reflection feature to this extent. That's why I wanted to know if anyone could figure out a reason from studying he code. Maybe with Combat there was barely enough ROM to finish the game. Remember that in those days there was a lot of latency between entering the code and testing it on the hardware, so despite all good intentions, some bad code might have stayed in there because they were not able to go through enough iterations to see everything they were doing that clearly. In the very earliest days they actually had to write straight machine language on paper tape. What they did got the job done, and in 2K, so it's not a tragedy. I just don't understand the thought process. I think similar idiosyncrasies were discovered in the coding style of Surround, right? It could be that another game might have precipitated the reflection feature if it had already been in development while the 2600 was in evolution. The very earliest games were written on prototype hardware. But by early 1977 I think the hardware was fixed. Maybe for Air Sea Battle? Canyon Bomber would probably have been too late. I would think that any game that has sprites that only move left and right (coinop titles of that era like Sea Wolf, Sky Diver, etc...) would use this feature so maybe it just seemed like a no-brainer to put in. Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://stella.biglist.com
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