Date   : Wed, 03 May 2006 22:56:52 +0100
From   : Peter Rendle <pete@...>
Subject: Re: Western Design Center W65C02S

Sprow wrote:
> I don't think so, or at least not directly.
>
> The WDC parts have a few extra pins (variously previously N/C, same name but
> opposite direction), the result is you'd need to do some track cuts and add
> pullups as appropriate - for example one of the output pins is hardwired to
> +5V on the BBC motherboard.
>
>   
>> Or would I be best building one into a second processor and running it 
>> at 14Mhz? ( Probably tricky!!)
>>     
>
> The intimate relationships between timing on the BBC means you can't easily
> jack up the CPU rate without melting the VIAs/patching software timing loops
> in filing systems/getting video coming out at the wrong rate/etc...
>
> I'd suggest using one in a second processor would be simpler since you only
> have the RAM timing to worry about then, and frankly there's no reason to
> use DRAM for 32k now - a 70ns SRAM will suffice.
>
> Of course I'd have to sway you towards an ARM coprocessor in favour of
> trying to squeeze a WDC part onto the Tube,
> Sprow.
>
>
>
>   
The ARM coprocessor does look very sexy! (Its on my birthday list)

Seeing you are obviously the person to ask.....

Would a normal Tube ULA cope with interfacing to a faster coprocessor?  
And if not are there any alternatives?

Regards

Peter