Date   : Fri, 17 Aug 2007 19:04:47 +0100
From   : pete@... (Peter Rendle)
Subject: Homebrew TUBE ULAs

Jules Richardson wrote:
> 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?
>   
Sprow's ARM coprocessor must do this.
> 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!)
>   
If you used a big enough FPGA then you could fit the processor in there 
as well!
> [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
>
>
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