apart fron the editoe problems, It was used to write a control program for a cnc mill which talked to an Isa card that controlled stepper motors. The program took a basic description of the part to be milled and converted it into tool movement steps. this was all 2d but the parts were quite complicated as were the calculations. Tool movements is what killed it. We started with a list of lists structure but that took up too much ram so we moved to a skip list implementation. That also took too much ram so it was back to a singly linked list and an external preprocessor. So it turned from an elegant tool into a few chunks of ugly which had to be chained. That really doesn't work well on DOS. This was before EMS etc so 640k of segmented vomit it was. It was moved to a dedicated 68k SBC eventually with the ui in turbo pascal (over a serial line) which worked well and we could throw 4mb at it and write the control program in c using a cross compiler on unix (plus no segments=bliss).

I love 32+ bits these days :)