Jump to content

slx's Photo

slx

Member Since 19 Oct 2003
OFFLINE Last Active Today, 2:42 PM

Posts I've Made

In Topic: Ultima for 400/800

Today, 12:41 PM

Didn't the Atari version rely on artifacting for colors?  Wouldn't that mean the game would be basically black and white on Pal systems with weird bit patterns intended to produce colors.  Even on NTSC colors would have been different between machines because not all produced the same set of artifact colors.  

 

There is artifacting on PAL machines, it was green/blue on my monitor but it's probably not where the authors wanted it.


In Topic: Boot Disk Games. No directory

Today, 8:43 AM

BITD (up to at least 1985) pretty much all commercial floppies were SD as that was the lowest common denominator. The next most useable format would probably be 1050 enhanced density, but that's as useless for anyone not using a 1050 as double density is to users of a stock 1050. 

 

As probably stated a million times here, it's really a pity that Atari chose not to use double density on the 1050 to save a RAM chip.


In Topic: The UAV Rev. D Video Upgrade Thread

Yesterday, 5:11 PM

In my research I came across a disturbing and misrepresented piece of history as told by Wikipedia...

 

I don't know who wrote this piece of drivel, but it certainly wasn't someone who knew anything about the Atari 8-bit line  ;) .

 

- Michael

 

If you find wrong information on Wikipedia, just hit "EDIT" and correct it ;)


In Topic: Boot Disk Games. No directory

Yesterday, 5:09 PM

Inside Atari DOS has an explanation of the boot process in chapter 20. The first sector of the disc needs to contain information on how many sectors to load where and where to jump for initialization and further program execution.

 

I never programmed for >48K memory but I am quite sure that you can't fill all of its memory in one boot process as you need some code to do the bank switching in between. So you'd probably have to use direct floppy access and read your data sector by sector to get the rest (for this you set up the parameters at $300 and up and then JMP to DSKINV at $E453 to do the work. Mapping the Atari contained enough information for my younger self to accomplish this.

 

Such boot discs don't need a directory at all as long as your code "knows" where to find what. 

 

As long as you only read data from the disc or write fixed-length stuff back this is probably easier and more compact to implement in assembly language than DOS-based file access and will save a little floppy capacity as you can use all 128 or 256 bytes per sector without losing memory for the link bytes (plus of course the space used for directory and VTOC, as you mentioned). 

 

The obvious downside is that it will work with discs or disc images only, thereby eliminating some modern storage options that don't support disc images. A more elegant and portable way would be to use XBIOS (which I have not tried yet).

 

BITD I found it neat that the Atari could do this while the C64 AFAIK can't auto-boot floppies at all.


In Topic: Atari 7800 power connector is not proprietary: found a few donors

Yesterday, 2:52 AM

Would be nice if he would cut the cords and sell them in bulk to one of\many of us. He can recycle the rest as he plans.

 

I just contacted him and asked him for a few cut-off cables. It would probably make more sense for a US or even OKC user to try to get any unsold stock and sell it off over time or make some extra money by attaching the cables to modern transformers.