<I get some error messages with restor (``Missing address (header) block'' <which I believe are to do with the 10,240 byte record requests from resto <My code expects 512-byte requests, and I'm doing 20 a time to fulfill th <10,240 request, but still problems. Try slowing down. You may be overflowing the input buffer. This was a common problem on TU58s hooked to the 2nd DL on some systems at speeds above either 4800 or 9600. It only happend in the TU58 to host direction (read) as the opposite path expected a handshake every 128 bytes(to allow the tu58 to actually do the write to tape). It seems the tu58 would send a 512byte block as 4 128byte packets at a sustained rate fast enough to overrun the PDP-11 host input buffer; before it could be emptied. You may be emulating a similar problem. PCs do not service interrupts all that fast and OS overhead can make that longer. Note PDP-11s can have enough overhead and higher priority stuff ahead of the 2nd DL that it cannot take data at greater than 4800 baud (sustained rate) without some kind of handshake to allow processing in between. If the system is basically unloaded like my minimal 11/23 it can run at 38.4! The most likely time when this overrun can happen is while doing processing to write (via file system) to disk and recieving data at the same time. Allison Received: (from major@localhost) by minnie.cs.adfa.oz.au (8.8.5/8.8.5) id JAA21620 for pups-liszt; Sat, 31 Jan 1998 09:06:40 +1100 (EST) X-Authentication-Warning: minnie.cs.adfa.oz.au: major set sender to owner-pups(a)minnie.cs.adfa.oz.au using -f Received: from henry.cs.adfa.oz.au (henry.cs.adfa.oz.au [131.236.21.158]) by minnie.cs.adfa.oz.au (8.8.5/8.8.5) with ESMTP id JAA21615 for &lt;pups(a)minnie.cs.adfa.oz.au&gt;; Sat, 31 Jan 1998 09:06:37 +1100 (EST) Received: (from wkt@localhost) by henry.cs.adfa.oz.au (8.7.5/8.7.3) id JAA07375; Sat, 31 Jan 1998 09:06:43 +1100 (EST) From: Warren Toomey &lt;wkt(a)henry.cs.adfa.oz.au&gt; Message-Id: &lt;199801302206.JAA07375(a)henry.cs.adfa.oz.au&gt; Subject: Re: Installing PDP-11 UNIX w. no tape - solution To: allisonp(a)world.std.com (Allison J Parent) Date: Sat, 31 Jan 1998 09:06:42 +1100 (EST) Cc: pups(a)minnie.cs.adfa.oz.au In-Reply-To: &lt;199801301446.AA19117(a)world.std.com&gt; from Allison J Parent at "Jan 30, 98 09:46:31 am" Reply-To: wkt(a)cs.adfa.oz.au X-Mailer: ELM [version 2.4ME+ PL22 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-pups(a)minnie.cs.adfa.oz.au Precedence: bulk In article by Allison J Parent: I found the problem - my dump image was corrupt :-). I now have a clean v7 dump of /, and there are no complaints from restor. I've had a few people volunteer to try out the code. I'll clean it up, finish off the docs, and put it up for ftp in a few days, with an email on the PUPS mailing list on how to retrieve it. Cheers, Warren Received: (from major@localhost) by minnie.cs.adfa.oz.au (8.8.5/8.8.5) id QAA22547 for pups-liszt; Sat, 31 Jan 1998 16:52:16 +1100 (EST) X-Authentication-Warning: minnie.cs.adfa.oz.au: major set sender to owner-pups(a)minnie.cs.adfa.oz.au using -f Received: from moe.2bsd.com (0(a)MOE.2BSD.COM [206.139.202.200]) by minnie.cs.adfa.oz.au (8.8.5/8.8.5) with ESMTP id QAA22542 for &lt;pups(a)minnie.cs.adfa.oz.au&gt;; Sat, 31 Jan 1998 16:52:10 +1100 (EST) Received: (from sms@localhost) by moe.2bsd.com (8.8.5/8.8.5) id VAA23209 for pups(a)minnie.cs.adfa.oz.au; Fri, 30 Jan 1998 21:36:05 -0800 (PST) Date: Fri, 30 Jan 1998 21:36:05 -0800 (PST) From: "Steven M. Schultz" &lt;sms(a)moe.2bsd.com&gt; Message-Id: &lt;199801310536.VAA23209(a)moe.2bsd.com&gt; To: pups(a)minnie.cs.adfa.oz.au Subject: Re: Installing PDP-11 UNIX w. no tape - solution Sender: owner-pups(a)minnie.cs.adfa.oz.au Precedence: bulk Hi - I thought I'd chime in with my experience with "high" speed serial transfers... The TU58's lack of flow control (unless you were on the Vax-750 with something I believed was called the MRSP roms) made them all but useless except in a 'standalone' environment. As a boot device they were just "slower than molasses in January". As a data storage device to be used while the system was up and doing other stuff the TU58 was quite poor. I tried to use the TU58 on an 11/44 once and it just wouldn't work reliably when trying to transfer a file from TU58 to disk. The first time the system had to tape a couple milliseconds to write a block to disk you had a DL11 overrun and the transfer was corrupt. The DL-11 to which the TU58 was attached (could it be hooked up to something a bit better? I would think so but don't know for sure) had no buffering/silo - at 9600 there was only 1 millisecond to get the character and that's cutting things a bit too fine on a ~.5 mips machine, especially if other things are going on at the same time. Ummm, 'PC's I'm used to don't seem terribly upset at 10 or 20 thousand interrupts per second - that should be sufficient to handle any 9600 baud serial line I'd think. Not 'overhead' as much as just 'slowness'. An 11/44 is about .6 mips (an 11/73 is about 15% less) - that's quite a bit less than even a 286. The biggest problem I ran into was the fact that the disk systems all used SPL-5 while the serial ports (DL11,etc) were at 4. A disk interrupt would (and did) come in and would delay things just enough that the DL running at 9600 with no flow control would overrun. If it's not doing too much else. I don't see an 11/xx handling high serial line rates without some form of RTS/CTS flowcontrol while a kernel recompile is going on ;-) If you're using a DHV-11 the data flow rate is quite a bit less than 38.4k - the bit timings are that fast but the board can't handle it and the effective rate is lower. A DHQ-11 is quite a bit better but all in all anything over 9600 requires hardware flow control, especially if the data has to make its way to disk. Steven Schultz Received: (from major@localhost) by minnie.cs.adfa.oz.au (8.8.5/8.8.5) id FAA24275 for pups-liszt; Sun, 1 Feb 1998 05:19:03 +1100 (EST) X-Authentication-Warning: minnie.cs.adfa.oz.au: major set sender to owner-pups(a)minnie.cs.adfa.oz.au using -f