Date   : Tue, 26 Oct 2010 07:32:29 -0500
From   : jules.richardson99@... (Jules Richardson)
Subject: Reversing the Tube ULA (destructively)

Rick Murray wrote:
> On 26/10/2010 05:53, Phill Harvey-Smith wrote:
> 
>> I believe his clone, doesn't have as many bytes in it's FIFOs,
> 
> Yes, I remember, though this could just be a limitation of the 
> programmable logic he used - that adding a larger FIFO would not have 
> provided suitable gains for the work involved?
> 
> 
>> and I seem to remember him saying that it didn't do DMA I think,
> 
> The Tube does DMA!?
> 
> 
> I suppose the question is, do we want an EXACT replica, or "something 
> that works"?

Personally, I want a drop-in "open" replacement which behaves (electrically 
and from a software point of view) exactly like the original. "mechanically" 
is less of an issue, I think - yes, it'd be great if it were just a 40-pin 
DIP, but I think most (if not all) of the copros had a reasonable amount of 
clearance around the socket such that a slightly larger footprint would still 
be workable.

Exactly *how* the replacement is arrived at, I don't care - e.g. whether it's 
from analysing the original hardware, finding the original designs, studying 
the documentation, studying software that uses the TUBE etc.

cheers

Jules