Date   : Wed, 15 Apr 2009 20:02:07 +0100
From   : afra@... (Phill Harvey-Smith)
Subject: ReCo6502 now available

Mark Haysman wrote:
> You're not going to need anything so fancy to just do the ULA (altho the 
> complete caboodle with it sounds good!). A CPLD may do it, but not one of 
> the smaller ones. Register 1 is a 24 byte FIFO (and Reg 3 is  a 2 byte 
> FIFO), so that's 208 registers before you even start on the others, status 
> registers and control logic, altho the app notes say that R1 is only used 
> for 10 byte VDU command length transfer, so maybe the size of it could be 
> reduced without too much affect on performance. You could always place the 
> RAM outside the CPLD, but that then defeats the "single chip" neatness. 

Dual port ram with CPLD controling springs to mind.

> There are certainly chips that it will fit into with ease, it's just a case 
> of balancing the cost to make it worthwhile doing.

The real pain with CPLDs is that it seems as the number of logic blocks 
goes up so does the number of pins, making accessing a CPLD with enough 
registers harder as it means a large pincount, hard to solder surface 
mount package. Believe me soldering a 100 pin package with 0.5mm pins is 
no fun at all :(

Cheers.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.