Date   : Sun, 10 Mar 2013 18:28:43 +0000
From   : philpem@... (Philip Pemberton)
Subject: Qudos MINICHIP / Quickchip ECAD and Ferranti ULA

On 26/02/13 19:31, Ed Spittles wrote:
> - a page of a document describing the (related) R series, which
> confirms that all designs are NOR based - this probably tells us that
> storage is done by cross-coupled NORs.
> http://www.cl.cam.ac.uk/~atm26/acorn/electron/ula/ferranti-r-series-cell.png
> 
> - clean copy of a ULA cell
> http://www.cl.cam.ac.uk/~atm26/acorn/electron/ula/asic_1a.png

Thanks for that -- I *think* I've figured out the cell layout using the
"substrate" image from Visual6502. The only problem being that it's
impossible to identify base from emitter as these aren't visually
distinct. It is, however, possible to make an educated guess :)

The peripheral cells are still a mystery...

Thus far I've cleaned up the substrate and die-shot layers and merged
them into a composite which *should* be usable for entering into Degate.
>From there a netlist can be produced - then the fun of converting
transistors to gates begins...

> It seems that the two cell designs are logically equivalent.

I'd concur -- it's just the resistor and current source layout which
appears to differ between the two ULA variants.

-- 
Phil.
philpem@...          
http://www.philpem.me.uk/