[Coco] Fwd: IP packets on my coco

[John W. Linville]

On Wed, Jun 08, 2016 at 11:38:23AM -0500, RETRO Innovations wrote:
> On 6/7/2016 4:16 PM, John W. Linville wrote:
> > On Tue, Jun 07, 2016 at 12:40:29AM -0500, RETRO Innovations wrote:
> > > On 6/7/2016 12:31 AM, Stephen H. Fischer wrote:
> > > > What the ????
> > > > 
> > > > I see the board image but it quickly is replaced with (Soft Porn?)
> > > Hmmm, not sure what is going on there...  It didn't do that for me, but
> > > postimage looks to be putting ads on the side...
> > > 
> > > Anyway, here is another version, off my web site, no ads:
> > > 
> > > http://go4retro.com/downloads/CocoNIC.png
> > Ah...well, that is very tempting.  What do I have to do to get one??
> > 
> > John
> 
> No big deal to get one prototyped.  The main question is:
> 
> 
> rtl8019 or cs8900a
> 
>  * cs8900a pros
>      o a bit more code available from the 65XX crowd
>      o Slightly easier to produce, as I have all parts here.
>      o AutoCRC?

The datasheet I find on the web makes it very clear that the chip
can generate CRC on transmit.

>  * cons
>      o No IRQ capability.  You must poll for all packets

Why is this? The datasheet clearly shows IRQ lines -- not surprising
since the part was designed for the ISA bus.

>      o More expensive to produce (cs8900a is ~$10/pc)
>  * rtl8019 pros
>      o IRQ capability
>      o A bit cheaper to produce ($rtl8019 is ~$5.00/pc)
>  * cons
>      o A bit less code from the 6XXX crowd
>      o A bit tougher to produce, as I need to source the parts (not a
>        huge deal)
>      o No AutoCRC?

Bit 0 of the Transmit Configuration Register would seem to offer CRC
generation on transmit.

> I know the 65XX crowd laments the lack of cs8900a IRQ, but the design is
> proven.  So, I leave it up to the community.

I have no idea what design issue might have painted them into this
corner, but the datasheet suggests that this shouldn't be a general
issue with the chip.

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.