Aside from having to learn the timing spec's for the display you want to generate, you'll need some components.

You;ve made no mention of how experienced you are with programmable logic, so I'll assume that's not on the list of thigns you want to use.

As you know, CRT displays are raster-scanned, i.e. they sweep a single focused (we hope) dot across the front face of the CRT, modulating it on and off to create an image. Part of the time, it is swept slowly and modulated on and off to varying degrees to control the brightness of the light emitted by the phosphor on the front face (anode) of the tube. A smaller part of the time is used to move the dot back to the side whence it started, and once each scan, from bottom to top, assuming its active scan is from top to bottom. The sweep circuit can be though of as horizontal and a vertical relaxation oscillator, one operating at the horizontal rate, and one at the vertical rate. The first thing you have to find out is what those nominal rates are, because the closer you drive thie tihng to that nominal rate, the less trouble you'll have.

This presents a problem to the designer of a digital interface such as what you want to design, and what that problem is, is to control the state of either the grid or the cathode voltage, by means of the internal video amplifier(s) such that the "dot" is in the correct state at the correct time.

There are many ways in which to do this. I'd suggest you look at a few microcomputers of the late '70's, e.g. the Apple-II in order to learn how it's done. That one was done with nothing customed up for them, i.e. you could buy each and every part directly off-the-shelf. It was capable of color on an NTSC-compatible monitor.

I'd suggest you familiarize yourself with the Motorola MC6847, also, as an alternative that can put a considerable, though not very satisfying amount of text on the screen. There's also the Motorola MC6845, which is a video timing generator intended to be the core of what you're considering. I'd give that one a hard look as well. Other manufacturers had other approaches to solving the same problem, but theirs was probably the most popular, and not without reason.

Take a look at those chips, take a look at the EIA RS170A standard, and then see whether you still have an appetite for this job.

RE