Re: WANTED: Translator from German

Rather than parallel why not SPI as implementing that is far simpler.
hard ware needed is an out put bit and input it and a birdirectional
clock.
Yes, you can do that even directly with the WIZnet Chip, it can work
in SPI-Mode. But you would need the same on the Z80 side - I have not
a SPI-Interface in my Z80-System but I have a so called Digital In/Out
Modul ready for such experiments and a PIO is simple enough for me.


There are a few PICs and other chips that can do the bottom layers of
the stack to the media level and save a great deal of low level
software. Also there are Ethernet chips that will do the work all the
way to packet buffereing so that the host doesnt have to be fast to
do the higher level work.
Yes there are some very interesting projects, like http://www.sics.se/contiki/
or some implementations of software stacks with microcontrollers here:
http://members.home.nl/bzijlstra/

Why used Ben the same Chip for the newest project "Red Bokito" - it is
very simple to program and it works like expected, in my Interface
too. What the controller makes with the chip I can do with the Z80 in
the same way, all what I need is a simple and fast bridge to program
the stack with Z80-Assembler, my prefered language. This makes the
KCNET possible for me in my system now.

I don't know about most systems referrcences but most of the common
hard ware here are 4mhz Z80 and that can if pushed move around
50-60Kbytes/second.
Yes, now limits my 1,75MHz - System the speed, I think you can reach
about 50 kB/s with a 4 MHz System if the ATmega (my bridge on the
other side) can handle this. I can't test it.

If the device has the Z80sio/dart those can run
serial to 56K
The 56K are kBit not kByte.

 Going
parallel will not gain much speed over that.  Its a matter of CPU
speed and cycles needed to do transfers.
I think it is a difference between 56kBit and 448kBit or 7 kByte and
50 kByte, by the way, for usability you need a minimum of about
7...10 kByte/s, this is my personal experience so far. Thats why I
prefer the parallel hook of the interface.

However if the eithernet inerface can buffer packets so that the
host
runs at it's speed it will work smoothly and can even "feel"
responsive.
That is not enough, the handling of the packets between the layers of
the stack and TCP-Handshake for example is a time consuming and tricky
issue - all done by the hardware stack from WIZnet, I can and must do
only the rfc protocols in the Z80-system.

DHCP - I can't follow the send - receive messages of the client on my
screen, its to fast

TFTP - the data packets with the filedata are so fast, that the hdd
can't write them

PING - here you work on the IP-layer and must calculate the IP-
checksum on the host (Z80) for incoming and outgoing PING-Messages and
measure the time from send to receive - the time has a deviation of
100 ms, when you ping the CP/M Host while he is pinging by itself then
you can "see" the Z80 hard working, the answer times goes up to 120 ms
with spikes up to 400 ms


OK - I think enough information, I must continue my work in the next
time, I answer to all questions here ore per email but writing
comments consumes too much time in the moment.

regards Ralf Kästner

.

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