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From: terry@spcvxb.spc.edu (Terry Kennedy, Operations Mgr)
Newsgroups: comp.os.rsts
Subject: Re: Optimizing serial transfers
Message-ID: <1990Dec20.194628.908@spcvxb.spc.edu>
Date: 20 Dec 90 19:46:28 GMT
References: <6437@crash.cts.com>
Organization: St. Peter's College, US
Lines: 40

In article <6437@crash.cts.com>, billdcat@crash.cts.com (William Mortimer) writes:
[text moved]
> Please respond via e-mail if you can help me out.  Thanks in advance!

  I responded via mail as requested, but thought the information might be of
general interest, so here it is:

>1)  Can KERMIT be optimized so the transfer will take less time?

  Yes - I'm working on a newer version of Kermit for RSTS. The current one
is rather inefficient, especially on input - it runs the scheduler on every
input character.

  You should use the longest packet size you can get. When the RSTS system is
receiving, you may have to shorten the packet size to eliminate data loss.

>2)  Can the machine's operating system be optimized in some manner so the
>    transfer will take less time.

  Depends. If you are using a DZx11 or DLV11 interface, you are generating
an interrupt per character sent. For sending from the PDP to the PC, using
a DHx11 would be a big improvement.

>3)  Is there a better protocol that I can use under RSTS/E that will allow
>    faster transfers?  IF so, where can I get the source code?

  I have a version of XMODEM in BASIC. I could send you that if you'd like to 
try it.

>4)  Is there another way to go in through a serial port that doesn't require
>    any additional hardware?

  Leaving out the serial port bit, the best way to go is to get DECnet/E on
the PDP (software and Ethernet controller) and on the PC (likewise). You can
get up to 14Kbytes/second that way. It's a bit costly, but if you need the
speed, it's the best way.

	Terry Kennedy		Operations Manager, Academic Computing
	terry@spcvxa.bitnet	St. Peter's College, US
	terry@spcvxa.spc.edu	(201) 915-9381