[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: [N8VEM-S100:273] Request For Comments (NIC Board)
- To: <n8vem...@googlegroups.com>
- Subject: RE: [N8VEM-S100:273] Request For Comments (NIC Board)
- From: "Andrew Lynch" <lyn...@yahoo.com>
- Date: Sun, 12 Jun 2011 11:23:48 -0400
- Authentication-results: gmr-mx.google.com; spf=pass (google.com: best guess record for domain of lyn...@yahoo.com designates 126.96.36.199 as permitted sender) smtp.mail=lyn...@yahoo.com; dkim=pass (test mode) head...@yahoo.com
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1307892232; bh=G2cEf9F/Wc8M9A8VYRX3jXV5dvAhrTMgpDDiiIkqRuI=; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:References:Subject:Date:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Mailer:In-reply-to:Thread-Index:X-MimeOLE; b=Xx9Q/kx6GW+XDPAkHgyZ6lJDXIELvVo5IW+DDnjCTKaKEJAwgM9G1i5+4km0jJjlT9FVasJVo3VyGGnlvYtZ7Qod3LL+fOuNCrkqK9DEq4A8r0mPp/cxrGDGGML0dsMngF+BIAKRLcBrb9sbudyVtIBwHeF4RO2PQ1ggrmIx6NM=
- Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=DKIM-Signature:Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:References:Subject:Date:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Mailer:In-reply-to:Thread-Index:X-MimeOLE; b=ws7VHHSkLYn+O+STURMfOaMpNQ85rbBEdytetld+kqMCXYVKeUF9qwY4XswqveQLk7SMkWJJfvYztYQ8BazfOZfY0t58lfXB5XKtrwuJYwMBQS1Xv0V1SCkSs7xfpEoHq1AUgYSGuMpptxXGMSqqXAO+lbwp6s522VgvDWiSFS4= ;
- In-reply-to: <40319CEB-1490-4143-A2C4-0E7A84659B5D@mac.com>
- References: <4DE84559.email@example.com> <4DE851C2.firstname.lastname@example.org> <EF4EEF362BDF4051BD379153C2C34DD3@andrewdesktop> <4DF06858.email@example.com> <40319CEB-1490-4143-A2C4-0E7A84659B5D@mac.com>
- Thread-index: AcwmcwmJWJsZe/mBR9qs/z3s1GivyQCnhSxg
Hi Douglas! Thanks! You have to admit though, even 10 Mbps Ethernet on an
S-100 bus system would be something to see. I do like the idea of moving
the TCP/IP stack to the NIC4 Z80 like using CP/NET or something akin to
Max is running CP/NET on the N8VEM home computer prototype so it is
certainly possible. I am not sure how that would work though. For most
applications, the 10 Mbps link would sufficient for most any S-100 based
application if not overkill.
Thanks and have a nice day!
> -----Original Message-----
> From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On
> Behalf Of Douglas Goodall
> Sent: Thursday, June 09, 2011 2:54 AM
> To: n8vem...@googlegroups.com
> Subject: Re: [N8VEM-S100:273] Request For Comments (NIC Board)
> I looked over the specs for the ENC28J60 and I have some thoughts...
> The chip is interfaced via SPI, which although fast is still a serial
> The chip has on-board dual ported ram which is used for incoming and
> outgoing packets.
> One of the things that slows down protocol stacks is the need to copy
> buffers around
> (something I learned in signal processing).
> When a packet arrives, I assume it is placed in the dual ported ram of the
> and can then be copied into the lower 4K at the bottom of the Z80's ram
> space. From
> there it would get copied yet again into the hosts systems space for
> further processing.
> I can see several ways to make this all work better. For one thing I think
> adding four
> interfaces to the card is overkill. If the board could do a really good
> job with just one,
> that would be something.
> You have to make a decision about how the board is to be used, and where
> the TCP/IP
> stack is going to live. Lets say you put this board into a Z/80 system in
> an S-100 bus,
> memory is short enough for the master CPU without having a full TCP stack
> Doing a better job with just one channel might include making the master's
> window into
> the ram space of the on-board CPU the same size as the dual ported ram on
> ENC28J60. Then the master would have access to the entire buffer space.
> The Z80
> on the board could manage the ENC28J60 and signal the master via IRQ or
> with a DMA terminal count condition.
> Also the ENC28J60 is a 10base-T interface which I believe is limited to
> Just some thoughts...
> On Jun 8, 2011, at 11:29 PM, mike wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > Hi All,
> > I just sketched out a design for a 4-port Ethernet S-100 card. I likely
> > won't get around to producing this for a while since I have enough on my
> > plate to keep me busy for quite some time, but it would be good to start
> > getting the ball rolling a little bit on something like this.
> > http://www.8bit.geek/index.php/s100-cards-in-development/nic4-4-port-
> > In a nutshell, it has an on-board Z/80 that bit-bangs an SPI bus
> > inter-connecting 4 ENC28J60 MAC/PHY ICs, and the Z80 has 32K of ram to
> > use as scratchpad and buffer space. The S100 master has access to a 4K
> > window at the bottom of the Z80s 32K RAM. There is one I/O port for
> > communicating comamnds and status between the S100 master and teh
> > on-board Z/80. The Z/80 can interrupt the bus master and interrupt
> > vector(s) are software programmable.
> > Welcoming comments.
> > - --Mike
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.4.10 (GNU/Linux)
> > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
> > iQEcBAEBAgAGBQJN8GhUAAoJEEzVYN3s3Af7GLMIALjCxGsuNI1Fji/W3AhEgbbR
> > v7DJxNS+OqxBeF56GjLPrAUjypxKzLGdowVEFe1HiBzn/2UHyxKl6Xap/do9lSMM
> > uSTd9C7KCrzcuCYdW6neRKfY3SfPsBre2eclWBNcrr5UnlgvOySC5y+Fc+JD1M4D
> > xJ6O/fMrKjofohKD6COB5mUI9WTFUOt3km0Numh2X/pjYTovAUWBUfDJG124WShE
> > ae3rx3bWpl8ywVO+6LO1ndQFtQ26GbJbEM34XaJIZkXQS1HlEIIRF5A8zHm4yLdI
> > 0sq/YI3tOtGxXqOhCnC3+6+avetOSlq4dndUi3gWjGd5bkRv9KLbGpzhi7OP+rI=
> > =J8Zo
> > -----END PGP SIGNATURE-----