The Atari 1200XL

NTSC/PAL/SECAM & PERITEL?

If you do not know what these acronyms refer to, please read the "NTSC/PAL/SECAM/PERITEL" article in the knowledge base first.

The computer

Although it was produced only for a few months in 1983, the Atari 1200XL is common in the USA. Some sources^{1}, based on serial numbers, estimate that it is likely that just over 110,000 units Atari 1200XLs were manufactured (+ 250 "pilot" units in fall 1982).

{1} "1200XL Owners Club (serial tracker)" from AtariAge.org

Still, it remains much more difficult to acquire for European collectors like me simply because it was never sold outside the USA.

The 1200XL has some unique features, found only on this model. For instance:

1. Two LEDs labelled L1 and L2, just above the keyboard. They are normally off.
   L1 lights up when the keyboard is disabled.
   L2 lights up when the new International Character Set is selected.
   Note: the L1 and L2 LEDs were also present in the 1450XLD computer, which was never released and remained as prototype.
   
2. Four function keys labelled F1 to F4.
   Note: the four function keys were also present in the 1400XL and 1450XLD computers, which were never released and remained as prototypes.
   

Top

Keyboard, left

Keyboard, right

Rear

Left side

Joystick connectors close-up

Right side

Bottom

Nowadays, I am still amazed by the timeless modern look of the XL series. An Atari XL (800XL) was recently included in a French auction of 2,000 objects with iconic design, ranging from Dieter Rams (for Braun) to Le Corbusier (who was credited for a radio set).

Made in

I am very lucky — for a European Atari collector — to own several 1200XL, including a model made in the USA and another model made in Taiwan.

Made in USA, 163 is manufacturing date in WWY format: Week 16 of (198)3 = Apr 1983.

Made in Taiwan, 143 is manufacturing date in WWY format: Week 14 of (198)3 = Apr 1983.

The connectors

Rear close-up #1

Rear close-up #2,
with 5-pin 180° DIN Monitor socket

The superb Atari rainbow logo on boot up

For me it was not a waste of time, but a demonstration of power. I regret that this boot screen has been removed from subsequent versions of the OS.
For the video: Altirra emulator, Atari 800XL, PAL, 1983 OS rev. 2, running the 1200XL rainbow boot screen code in loop.

The new embedded "Self-Test" program

The "Self-Test" which will be an integral part of the OS on all subsequent machines first appeared with the Atari 1200XL. Please read the "Self-Test" article in the knowledge base for all details.

The keyboard test allows you to test the function keys F1 to F4 (introduced with the 1200XL). These keys will be physically removed from the 600XL and 800XL onwards but the "Self-Test" keyboard test will not be updated immediately, offering to test keys that no longer existed...

On the 1200XL, the RAM test will cause the L1 and L2 LEDs above the keyboard to flash alternately. As the 1200XL is the only model equipped with these L1 and L2 LEDs, this specificity will disappear with the 600XL & 800XL.

Also, on the 1200XL, Scott Stilphen mentioned in the FAQ (section: "What is the Atari 1200XL?") that if you select "All tests", when it gets to the keyboard test it'll type out the programmer's name: Michael Colburn. The updated version removes this name and types in some letters that don't mean anything.

The memory test is particularly long on the 1200XL. Skip to 4:40 to see the rest.
For the video: Altirra emulator, Atari 1200XL, NTSC, 1982 OS rev. A, running the "Self-Test".

Technical tips

According to Atari documents "Tech tip #18 (12 July 1983)" & "Tech tip #18A (29 Sept 1983)", 3 versions of ROMs containing the Operating System were installed in the 1200XLs:

1. REV. A, EPROMs (very first 1200XLs manufactured)
2. REV. A, ROMs (the overwhelming majority of 1200XLs)
3. REV. B, ROMs (the 1200XLs that have been serviced, probably due to abnormal behaviour of the [System Reset] key)

If you have the REV. A version on EPROMs, or the REV. B, your 1200XL is a rare model.

If your 1200XL encounters one of the following problems, please consult the Atari "Tech tip" documents to solve it:

• The screen distorts with high intensity (black to white) screens. Characters appear to be very wavy, torn or ghost images, and the video on the screen seems to enlarge.
• The audio is of poor quality or does not exist at all. The audio must be constantly readjusted or cannot be adjusted.
• No picture when the Star Raiders cartridge is powered up

PEEK identification

Using "PEEK" instructions in BASIC to find out about the OS, Basic and NTSC/PAL versions.

PEEKs to important addresses

For your information, the results are:
PEEK(53268) = 15 [NTSC]
PEEK(65528) = 191 [Not a 400/800]
PEEK(65527) = 10 [XL OS Rev. A, 1982-10-26, 1200XL (most)]
PEEK(43234) = 162 [Atari BASIC Rev. A, in external cartridge]

Video signals output

Here is a summary of the video signals available on this particular model.
To be able to use one of these video signals to display an image, you obviously need to check that your TV or video monitor has an input for the specific video signal you intend to use. If it doesn't have it, the easiest thing to do is to use a modern video converter/upscaler to convert the video signal available to you to HDMI, for example.

Special thanks to Jerome Delsarte for all this information and his expertise on video signals.