Re: TI-H: special component

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Re: TI-H: special component


The 50MHz pic wouldn't work either...  :)  Get one of the 10mbps chips from
national semiconductor and then a PPC403 for $28 and you can make a real
good interface...  You'd be better off buying an $11 ethernet chip than
trying to make a pic pretend...

>Don't you think that the chip would however, get backlogged with data after
>a while? i mean...it could in theory bring in the data and send it back out
>that quickly, however if it's planning on doing anything real with the
>data, i don't think that this will work at all well. however, if you can
>find a way to make it work on a 10 Mhz network. Please tell me. I've been
>considdering building a little device that connects to a modem and to my
>dad's office network and allows me to dial in and execute various tasks
>(i.e. reboot my servers there, connect via telnet to some of the firewalled
>workstations, that kind of thing).
>
>At 08:33 AM 6/18/98 -0700, you wrote:
>>
>>On Thu, 18 Jun 1998, Jon Olson wrote:
>>
>>> Seeing as the PIC only operates at 10 Mhz and the network operates at 100
>>
>>Just a minor technicality, but I think the high-end PICs max at 20MHz..
>>
>>They take 4 clock cycles to make an instruction cycle, so it's getting 5
>>MIPS. A 10 Mb/s (megabit) network (in theory) pushes 1.25 MB/s (megabyte)
>>of data. So if you had some sort of a shift register taking the data from
>>the network line and presenting it a byte at a time, then I think a 20
>>MHz PIC would be able to switch 10 Mb/s network traffic. (Did I calculate
>>all that correctly?) A 100 Mb/s network (also in theory) moves 12.5 MB/s
>>down the line. Since a PIC can read its I/O ports in a single instruction
>>cycle, it can take in 5 MB/s at 5 MIPS. So it has enough room left over to
>>push 10 Mb/s traffic back out another port, but it doesn't have enough
>>power to even read in a 100 Mb/s source without losing frames.
>>
>>So anyway, like Jon said, 100 Mb/s traffic is definitely out. But I think
>>10 Mb/s might be possible... unless I don't have a clue what I'm doing,
>>and that is also possible.
>>
>>--
>>Greg Hill
>>greg-hill@bigfoot.com
>>www.comports.com/link
>>
>>
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