Article View: comp.sys.amiga.tech
Article #1326Re: State of PD system enhancement (was: Two Amigas)
From: Matt Dillon
Date: Mon, 18 Sep 1989 20:19
Date: Mon, 18 Sep 1989 20:19
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:> diskperf NET: to my A1000's RAM: drive yields 25 KBytes/sec
:> (4096 byte buffers). Raw network throughput is 28 KBytes/sec.
:Is that the theoretical limit on the parallel port? I'd expect much
:higher throughput. The serial port can be driven up to 56Kbps or so,
:right? If (and I realize I'm making a big assumption here, but ...)
:IF it takes about the same amount of effort to send a BYTE down the
:parallel port as a BIT down the serial port, shouldn't the limit be
:around 56Kb/sec?
I've been talking to Ron Perry, who wrote the basic software
for a commercial 16 Amiga server using the parallel port. With
hardware, he is getting 100KBytes/sec out of it.
As far as the serial port goes, no, a bit is not the same
trouble as a byte on the parallel port. You write bytes to the
serial port register not bits so the trouble is the same.
56Kbps = 5.6KBytes/sec (10 bits/byte 8 bits + start + stop)
The current 28KBytes/sec throughput I'm getting over the
parallel port is about 35uS/byte. Most of the time is spent
hand-shaking between the computers. With the Amiga you can't
count cycles like you could on the old C64's and PETs so you
have to handshake.
:Hmmm. 2:1. Less of a difference than I'd thought at first. I'm
:probably just talking through my hat; ignore me... ;-}
nearer to 5:1. Theoretically, the maximum transfer rate over
the parallel port is ~8 to ~10x the maximum transfer rate over a
serial port using line loading limits.
I've heard people running the serial port at 262KBaud
(26KBytes/sec). The only way this can be done that I can think
of is (1) The machine must have FAST memory so the video doesn't
interfere, and (2) Interrupts must be disabled during the transfer.
That might be good for a hack file transfer but I can't make those
assumptions for interactive usage.
-Matt
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!POSTGRES.BERKELEY.EDU!dillon From: dillon@POSTGRES.BERKELEY.EDU (Matt Dillon) Newsgroups: comp.sys.amiga.tech Subject: Re: State of PD system enhancement (was: Two Amigas) Message-ID: <8909182019.AA06478@postgres.Berkeley.EDU> Date: 18 Sep 89 20:19:57 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 40