Here's one guys attempt at a digital Philips generator (PM5544).
http://homepages.ihug.com.au/~daz200.../TP/index.html
If you're familiar with the Philips generators, the patterns are all analogically developed. The chips are all soldered in. Digital would clearly be the way to go.
The Tektronix generator I have (TSG170A) the patterns are read out of proms.