[Coco] MPI replacements?

[jdaggett at gate.net]

The CPLD route is not all the panecia that it is cracked up to be. ALmost all new CPLDs are 
no longer 5 volt tolerent. SOme are still around that both input and output will drive 5 volt TTL 
logic. They are expensive. Some of the newer less costly CPLDs need level translation to 
properlydrive 5 V TTL loads as well as inputs.

just a thought
james 

On 10 Jul 2010 at 3:00, Little John (GIMEchip.com) wrote:

> Putting the whole thing in a CPLD would be the most flexible method. It 
> would allow entire restructuring of the device on the fly. I'll decide soon 
> as to how to proceed - I'm currently engrossed in the memory upgrade, which 
> is being problematic (human error, but I shall not give up)
> Thanks All - John
> 
> ----- Original Message ----- 
> From: "Phill Harvey-Smith" <afra at aurigae.demon.co.uk>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Saturday, July 10, 2010 2:29 AM
> Subject: Re: [Coco] MPI replacements?
> 
> 
> > On 09/07/2010 21:15, Rob Rosenbrock wrote:
> >> Rather than a GAL or discrete logic, have you ever considered using a
> >> small ROM? I've seen one implemented utilizing it as a truth table.
> >
> > The problem with using a Rom or a GAL/PAL is that you need an external
> > programmer to program the logic into them. Programmers for these devices
> > are generally quite expensive.
> >
> > The advantage with a CPLD is that they are generally in circuit
> > programmable with a cable that can be purchased or made relatively
> > cheaply. Also it makes changing the logic much easier. They are
> > generally available in PLCC (such as the Xilinx 9536/9572/95108 and the
> > XL versions) which means they can be socketed and don't then need any
> > surface mount soldering.
> >
> > Just my 2p/2c :)
> >
> > Phill.
> >
> >
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> 
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