Atari XL Series Computers - 1200XL  




A300 Project

(Pre-1200 Designs)






Sweet 16 Product Specification

Sweet 16 Operating System

Sweet 16 OS Supplement 1 - Self Test

Sweet 16 OS Supplement 2 - Relocating Loader

Sweet 16 OS Supplement 3 - Handler Loader

Sweet 16 OS Supplement 5 - Character Set

A1200 OS Manual Rev2 11/30/82

1200XL Test Spec 12/23/82


Atari 1200XL PBI Modification

Atari 1200XL OS Modification

Atari 1200XL Keyboard Fix

Atari 1200XL Clear Pic Mod










Atari 1200XL ClearPic   Version 128.3   5/31/2002   by Bob Woolley

I have been fooling around with the video on the 1200XL since I first hooked one up to a monitor oh so long ago. The first version of ClearPic was OK, but it did not have a composite output, just separate Chroma. As time went by I conceded that not having composite was too limiting, no matter how much better the video was as Luma/Chroma - particularly in the face of limited availability for separate Chroma capable monitors. (now, of course, there are a large number of s-video TV/monitors that look fantastic)

So, here is a pretty good upgrade for your 1200XL that looks really, really good on a s-video TV and has a decent composite output. And, it is fairly easy to do. I realize that other upgrades are available which really maximize the signal bandwidth but, some of the video is better not seen, I think. This version is designed to provide the best looking display, not the correctly engineered circuit.

By the way, if you want to hook up a stock Atari to a s-video TV or monitor, the Atari circuits are designed to be terminated with 75 ohm resistors. The old fashioned monitors had the option of using 75 ohm termination, but modern TVs do not. The result is an over-driven signal to the TV, which looks bad. So, if you want to hook an 800, for example, to a nice s-video TV, add 75 ohm resistors as terminators somewhere in the cable. Then it looks pretty good. You do not need this on ClearPic.

These instructions are presented as a list of components on the 1200XL board. For each listed part, remove the old device and add whatever is specified in its place. Those locations shown with a - are to be left empty. I have included a picture of a 1200XL board with all the listed components removed. The holes are then backlit to help you locate the components. Do a nice clean job and good luck.

Hope you like it.



Replace With


1 ohm


1 ohm


1 ohm








75 ohms


75 ohms


130 ohms


130 ohms








68 pf


1 ohm


1000 ohms




1000 pf


47 ohms

Add a wire from the junction of R27 and C61 to J2-5 (the empty pin on the video DIN connector)


html-ized by Dan Vernon -- May 2002