Date   : Fri, 17 Aug 2007 17:59:01 +0100
From   : julesrichardsonuk@... (Jules Richardson)
Subject: Homebrew TUBE ULAs

I was wondering whether anyone's ever tried bodging [1] their own TUBE ULA 
which plugs into the relevant 40-pin socket on a copro and appears to the 
system just like one of the original ULA parts?

I presume the complexity's not that high by modern standards - but is enough 
known about the pin functions and internal workings for it to be possible?

Given that they're rare parts and likely subject to a higher failure rate than 
most bits, maybe trying to duplicate the functionality is a useful project for 
someone (not me I'm afraid, I wouldn't know where to start with something like 
an FPGA!)

[1] I know Torch did their own thing, but I'm pretty sure their circuitry only 
looks like a TUBE ULA on the TUBE side of things; the 'interface' to the rest 
of the copro behind the scenes will be different, so it's not quite a drop-in 
replacement for one of the Acorn parts (even if it could be abstracted out 
onto some sort of daughter-board).

cheers

Jules