I try to answer to those questions in a way objective and suitable for newbies.
You'll find many other answers in Atari 8-bit computers FAQs.
Which computer to buy?
Historically speaking, Atari 800 is a milestone (compare it with contemporary 1979 computers!), but if you want a computer compatible with all software, you should take an Atari 800XL or a 130XE (65XE and XEGS are OK too). Their only limitation is that they have two joystick ports only instead of the four Atari 800's ports.
Cart port. If you use cartridges, 800XL cart position is more comfortable.
Design. 800XL and 130XE are both beautiful and original.
Keyboard. Important only if you plan to enter a lot of text. Overall many people prefer 800XL keyboards but 5 variants exists (avoid the last variant, Mitsumi).
Memory. 800XL has 64KB, 130XE has 128KB, usuful for few games (but now AtariAge user ctirad sells an external 320KB low cost memory expansion for 800XL).
Video ouput. RF and composite. 130XE has s-video too. With a simple jumper 800XL can have s-video too, but with a lower quality (to have an excellent s-video output you can make Kjmann s-video upgrade).
Quality. 800XL has a better building quality. Some XL's have all ICs socketed, so they are easier to repair and upgrade.
Basic. Important only if you want to program with Atari Basic. 130XE has bug free Basic rev. C. You can replace 800XL Basic rev. B IC with a rev. C. Anyway, if you like Basic programming, nowadays many people uses the fast, compatible and compilable Turbo-Basic XL so Basic's revision is unimportant.
What I need to run software?
If you want to use cartridges, you don't need anything apart your Atari 800XL/130XE.
If you want to use old 5¼ floppy disks, you need a disk drive (Atari 1050 and XF551): to load machine language programs, remember to turn on computer with option key pressed.
If you want to use old tapes, you need a program recorder (Atari 410, 1010, XC11, and XC12): to load machine language programs, remember to turn on computer with start and option keys pressed, then press play on program recorder and finally press return key.
If you want to run all existing software you have two solutions:
1 If you have and want a PC always near to your Atari you can buy
SIO2PC (AtariAge user classics, $60) and use it with APE Windows application (SIO2PC USB/RS232 version) or SIO2OSX Mac application (SIO2PC RS232 version)
SIO2PC-USB (AtariAge user sloopy, $30-45) and use it with AspeQt Windows application
SIO2SD/PC Combo (AtariAge user santosp, Euro 60, with case and SIO2SD) and use it with AspeQt Windows application
SIO2PC-RS232 (AtariAge user atari8warez, $32-42, lifetime warranty) and use it with APE or AspeQt Windows applications
With APE you can emulate not only disk drives but printers and modems too.
2 You can put all existing software in an SD card/USB memory and buy/build independent self-powered devices like
- SIO2SD (basic instructions):
AtariAge user lotharek (Euro 84.86 with case)
AtariAge user mega-hz (Euro 80 with case, Euro 35 without case)
AtariAge user Pigula (Euro 40 without case and SIO cable/connector)
AtariAge user santosp (Euro 60 with case and SIO2PC)
Atari Fan Store ($75 without case)
If you care about aesthetics, AtariAge user flashjazzcat can insert an SIO2SD into a 1064 (to match XL design) or an XM301 (to match XE design) case or inside the computer.
AtariAge user c0nsumer ($150 with case)
AtariAge user santosp (Euro 45 with case)
More Than Games ($100 with case)
- SIO2USB (documentation):
ABBUC (Euro 130-150 with case)
SIO2SD - SDrive comparison (I don't have a SIO2USB to compare, sorry).
If you like cartridges and their instant loading, you can put games in the Atarimax Maxflash Flash Cartridges (AtariAge user classics) or in the SIC! Cart (AtariAge user Stryker). To insert software in these two cartridges remember that you must buy Atarimax USB cartridge programmer or have a real disk drive or a SIO2PC/SIO2SD/SDrive device.
If you want fast loading/saving times - but you can load only single files (.xex/.exe) not disk images (.atr), unless you have Ultimate1MBinternal upgrade - you can buy SIDE cartridge (Lotharek, Euro 44.27)
This device has SpartaDOSX and a real time clock too.
Where to find software?
You can buy/find software on the Internet or in the real word, the price depends on conditions (loose, boxed, sealed) and rarity, and/or you can download it here:
Atari 8-bit Forever
Homesoft's Disk images
Vjetnam 8-bit Atari games Archive
Altirra (the best emulator for PC)
Colleen (official Atari800 port)
Emulators exists for Dingoo, GP handhelds, Pandora...
Edited by Philsan, Thu Feb 7, 2013 3:48 PM.