Date   : Sun, 12 Apr 2009 00:15:19 +0100
From   : mfirth@... (Michael Firth)
Subject: Faster, faster

Quoting John Kortink <kortink@...>:

>
> On Sat, 04 Apr 2009 17:40:00 +0200, I wrote:
>
>> [...]
>
> Okay, a more revealing snapshot (watch out, rather big,
> 4.7 MB) :
>
> http://212.123.133.121:8080/home/media/images/ReCo6502_Proto.jpg
>
> It is a 'remake' of the 6502 second processor for the
> BBC range. With a few extras that were irresistible :
>
> - Supports existing 65C02, 3 or 4 MHz
> - Supports WDC 65C02 or 65C816, 14 MHz (and can run
>   at this speed, i.e. with the ULA accessed at 3 MHz)
> - Supports up to 512 KB of RAM, which can (currently)
>   be bankswitched, or used 'as is' by a 65C816 running
>   in native mode (16-bit data, 24-bit addressing).
>
> The 65C816's native mode is (as yet) not supported by
> the Tube OS and e.g. BASIC. But it is possible to run
> machine code programs that temporarily switch to native
> mode and can then use 512 KB linearly addressable memory.
>
> The 'remake' does need the box and the original Tube ULA
> from an existing 6502 second processor. I.e. (as yet ...)
> it is not standalone, but either a replacement or an
> upgrade. This is, and will probably remain, its main
> purpose.
>
One question, which your mail today suggests you may already be  
thinking about, is whether this is intended only as a replacement for  
the external 6502 second processor, or
whether you are planning on a version that can fit inside a Master as  
a Turbo-turbo
co-pro?

I guess this could either be done by two PCB flavours, or (as I think  
Sprow has done with
the ARM7 board) making one PCB that can be connected up either way.

One big advantage of an internal unit, for those of us that don't  
already have an
external 2nd processor, is that the PSU etc is already taken care of,  
and it would just
be the challenge of sourcing a ULA chip.

Regards

Michael