Best disc format for level editor data

[+slx]

What would be the best way to store/retrieve level editor data for a DOS-less game (i.e. a game that auto boots or "kills" DOS on loading)?

 

From a "programming convenience" point of view it would probably be easiest to just do direct disk access without a file system and write the data to contiguous sectors, creating a fixed number of "slots" on a standard SD disc (image). AFAIK some Atari games use this for levels. This would allow sector copying of level discs but would require extra software for a PC-based editor to read and write such discs, however.

 

From a PC access/handling perspective it would probably be better to use standard Atari DOS format and include the necessary code to read a directory and sectors in the game as it would allow a PC to just write files that can then be copied using SIO2PC, etc.

 

Anything beyond this (ED/DD/other file systems) would require too much code IMHO.

 

Any thoughts?

 

(Not anywhere near a Shamus level editor yet, just thinking ahead while working on the code to use the C64 levels on the Atari.)

 

 

[Rybags]

In the modern day the big disadvantage of raw Dosless disk games is that transferring to modern IDE type devices isn't easy. It's not realistic to dedicate an entire partition to just one game.

But for a game where you want maximum available Ram and need to load level data as you go along then your options become limited.

You could use a Dos format still - the program code to do read-only file operations on a Dos disk is fairly minimal. Remember all those 4-5 sector boot menu disks? In essence they provide a sort of minimal Dos to load the games in.

 

For raw disk access, putting level data on from a PC would be a case of using a hex editor, then just remember the offsets and sizes of the data blocks you're dealing with.

 

As an alternative, you could also do the game such that it could utilize expanded Ram as a virtual disk and have a single file version. And a large flashcart version could do the same.

[NRV]

xbios?

 

https://atariwiki.org/wiki/Wiki.jsp?page=XBIOS

 

[+CharlieChaplin]

Hmmm,

 

loading levels contiguous = sequentially ? If so, there are various menu programs which can do this (none of them is DOS 2 compatible, full 128 bytes or 256 bytes per sector). Many of these menus have been used to load single and/or multi-stage boot-tapes and or hacked/cracked programs from disk however. http://ftp.pigwa.net/stuff/collections/holmes%20cd/Holmes%201/ATR%20Programs/Applications%20A-Z/index.html

 

- Sequential DOS

(type- in listing from Analog or Antic)

- Howfen DOS

- Elton C. menu

- Jon C. menu

- Mockingbird menu

- Alpha Load menu

- Ian K. menu

- Multiboot XL

- Rob C. menu

etc.

 

Afaik, the AURA menus are also using such a menu (or something similar)... http://mrbacardi.000space.com/aura/aura.html

 

Of course you can also use a DOS 2.x compatible (125 bytes per sector; 3 bytes sector/file-links)...

a) gamedos/minidos (presents a menu for several ML files, e.g. NanoDOS, MicroDOS, PicoDOS, MyPicoDOS, Fender's 3-sector bootmenu, etc.) or...

b) bootloader (to boot just one ML file, e.g. Picoboot by HiasSoft, Avalon-Bootloader by Mr. Bacardi, Auto-Booter by Keith Ledbetter, etc.). But then you have to provide your own loading routines to do multi-stage loading without a DOS

 

[HiassofT]

xbios?

 

https://atariwiki.org/wiki/Wiki.jsp?page=XBIOS

xbios seems to be missing some important functionality:

xBIOS Limitations

 

a) New files cannot be created.

 

b) Existing files cannot be extended in length.

so long,

 

Hias

[Rybags]

Much of the complexity of Dos is due to supporting those things.

A fix can be had to an extent - preallocate files. A games disk tends to be an exclusive use thing so you know what space should be available.

[xxl]

there are many Dos2 subformats, and because you do not need to worry about creating files xbios can work on anyone and keep the size of 1 kb.

And since it is designed for game creators, you should allocate separate files as "slots" or "albums" and file creation becomes completely obsolete.

(For more advanced creators you can allocate one any size file and use xNOTE - it works completely differently than in dos2).

---

if you don't want xbios then boot loader (xboot - 384 bytes) has load file function: xBOOT_LOAD_FILE equ $5f1

Edited August 25, 2017 by xxl

[+slx]

Thanks for all the input. XBIOS sounds like a good solution as creating levels on a PC based editor and reading them from an Atari floppy should work. If a level editor should run on the Atari it can run under DOS and use whatever DOS is installed to write files.