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 Post subject: Ultima II flashcart
PostPosted: Thu Jul 21, 2005 12:20 am 

Joined: Sat Sep 13, 2003 12:21 am
Posts: 251
I've done quite a bit of work on a Ultima II flashcart. Unfortunately there is an issue.

Ultima II consists of multiple maps, and each map loads into memory at $1000 with some additional information at $4D00. These locations are then written back to the disk, so that any treasure, roaming monsters, etc.. will still be there when you go back to that map. There are five maps that allow saving back to disk (none of the other planets maps do this saving.)

So that's 5 x 2 areas that need to be written to flash memory, plus your character information which is read/written to $4E00. That's 11 flash areas. What's the problem you say?

Basically, the easiest way to do this is to write each area to a seperate flash "sector" (a 64k block of flash memory). There just isn't enough room on the cartridge with the four disks, as well as the boot code, etc... (at least as far as I could tell.)

So, I decided that I would write all the $4D00 information to one flash sector. Unfortunately, the code to do this doesn't fit into the $CC00 area that Steve uses to store his flash disk i/o routines. With Ultima II there seems to be some space available in the $9x00 range that I might be able to use.

I guess I will have to modify the flash boot loader to load some of my flashing code into the $9x00 range and jump to that. It's made the project more difficult than I'd hoped it would be.

Any other suggestions from anyone?


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 Post subject:
PostPosted: Fri Jul 22, 2005 12:38 am 
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Joined: Tue Aug 05, 2003 9:55 am
Posts: 1035
Location: Cleveland, Ohio
How much extra code do you need to put in the $CC page and what exactly does it do?

Steve


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PostPosted: Fri Jul 22, 2005 1:29 am 

Joined: Sat Sep 13, 2003 12:21 am
Posts: 251
Well, what I am want to do is read a whole block of data from the flash cart to an area in $9x00 and then read from there the bit that is needed to go into $4d00. Same for writing. Read it all into $9x00 and then change it and write it back.

Maybe there is a better way to do it... I'll send you the code that I have... hasn't been tested though, since it didn't fit.


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PostPosted: Sat Nov 19, 2005 10:24 pm 

Joined: Sun Aug 31, 2003 9:50 am
Posts: 52
Location: Lansing MI
Shawn,

Say, did you ever get Ultima 2 to work?

Smeg


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 Post subject:
PostPosted: Fri Nov 25, 2005 10:09 pm 

Joined: Sat Sep 13, 2003 12:21 am
Posts: 251
Atari Smeghead wrote:
Shawn,

Say, did you ever get Ultima 2 to work?


I got very, very close. Basically two worlds aren't saving properly to the flash memory for some reason. I think I can track it down using Atari800WinPlus' debugger, but when I run it on my Windows98SE machine at home it crashes almost every time when I'm stepping through the code.


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PostPosted: Wed Dec 21, 2005 10:52 am 

Joined: Mon Apr 11, 2005 7:46 am
Posts: 48
Ultima II would be an awesome additional Shawn - Once you get things running if you need some assistance testing let me know.

I have a killer player from the 80's I built up if you need one :)



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