> So I started playing with my Atari 800.
>
> How do I work with disks? And what's the deal with this "Left Cartridge" /
> "Right Cartridge" thing? How does that work with something where it's
> obviously inappropriate, like with a 400 or 800XL?
I'm not an Atari expert -- the only 8-bit Ataris I've used are emulators.
But I have read the manuals, so I'll try to help. Also, some of this info
is online now. See
http://pmwww.cs.vu.nl/home/ipoorten/Atari.8bit.Homepage/index.html
Especially, look under DOCUMENTS and download the Atari System Reference
Manual. It's pretty well-written and explains a lot. (It is weaker regarding
the new machines, but you just have a plain 800 so that should be OK.)
Also see
http://ch.twi.tudelft.nl/~sidney/atari/
for some interesting memory maps.
Now... in order to work with disks, you must:
- Have the disk drive turned on before you turn on the computer.
- Have a bootable disk (which contains a boot loader and OS files --
for most versions of the OS these files are DOS.SYS and DUP.SYS).
- Turn on the computer and put the disk in the drive.
- If BASIC is not installed. you'll see a utility menu (provided by
the DUP.SYS program). If BASIC is installed, you'll see BASIC.
Type "DOS" to get the utility menu. To get back to BASIC from DOS,
I think you press A.
See the System Reference Manual for programming info (including the assembly-
language interface).
As for cartridges, the right slot is only found on the 800 I think. The two
slots occupy different blocks of memory. On the XL and XE machines, BASIC is
in ROM, but it's in the exact same area as the 800's left cartridge slot.
Cartridges can be different sizes (8K or 16K, I think 4K are also allowed) but
I don't know how that affects matters on the various machines.
Here's a quick memory map based on 6502 pages (1 page = 256 bytes):
0 Zero page.
1 Stack page.
2-5 Used by the OS, BASIC, floating-point routines, etc.
6 Free for your own use.
7-127 Main RAM area -- for machine-language or BASIC programs, DOS,
display lists, etc. OS variables MEMLO, MEMTOP, APPMHI create
partitions in this memory space.
128-159 Right cartridge slot, or RAM if there's no cartridge there.
160-191 Left cartridge slot, or RAM if there's no cartridge there.
(Only cartridge slot on most machines. BASIC ROM on XL and XE,
or RAM if BASIC is disabled.)
192-199 Unused. (Chips such as Omnimon go here. On the XL and XE, this is
RAM (or cartridge ROM?)).
200-207 Unused. (On the XL and XE, the OS starts here.)
208-215 Registers of the hardware chips (ANTIC, GTIA, Pokey, etc.).
216-223 Possibly more hardware registers, or possibly unused (the manual is
contradictory on this point).
224-227 The character set.
228-255 OS ROM on all machines (except for the last eight bytes, which are
reserved for 6502 vectors).
I think the Atari has a very sensible design, actually (though there are some
flaws). With enough looking around on USENET you should be able to find all
sorts of fun things to do with your machine.
Good luck,
-- Derek
Received on Sun Aug 09 1998 - 01:42:00 BST