Chan.CST%hi-multics@sri-unix.UUCP (01/11/84)
Could someone verify that the buffer size for receiving file while in terminal mode is about 2K for mdm716 but it is about 16K for mdm715 and before? Why if it is true? This is the result that i got using identical overlay and procedure to generate the .com files. I have also observed some interesting phenomenon and would like to see whether others are having similar problem. I discovered that while receiving data in terminal mode with a mainframe (I tried both Multics and a Cyber -- same results), when the buffer is filled, mdm716 sent the XOFF to the mainframe, but then several characters following the XOFF would screw up. The interesting part was that they were turned into some sort of control characters, showing up when i used mince to look at it, e.g. "a" became "~a", "7" became "~7" etc. However, the file would look correct when I used Wordstar to examine it, or just "type" it, or send it back to the mainframe using the transmit mode in terminal mode. Is there an explanation?
strom%brl-bmd@sri-unix.UUCP (01/12/84)
From: Charlie Strom (NYU) <strom@brl-bmd> You are quite correct that MDM716 has a 2K buffer rather than a 16K buufer. Being a devoted YAM user, I have not yet fiddled with 716, but there have been a number of complaints from users on Compuserve. I hope that Plouffe can advise us of the rationale for the change. The problem with extra characters (after buffer fill) that was determined to be a problem on CIS is that the routine used in MDM7 AFTER the buffer is filled does not strip parity, whereas the normal ASCII capture routine does. A simple fix would be to run the received file through PIP with the [Z] option set. Irv Hoff is hoping to release a new version fixing this. Of course you might tell your mainframe not to use parity if that is possible.
w8sdz%brl-bmd@sri-unix.UUCP (01/12/84)
From: Keith Petersen <w8sdz@brl-bmd> Please tell Irv Hoff that Bob Plouffe and Ron Fowler already have MDM717 "in progress" and we should have something forthcoming from them with these fixes in about a week. I'd hate to see all that good stuff that Bob Plouffe put in MDM716 "stripped out" by Irv "because he doesn't agree with it" or "doesn't like it". That's how we lost the "retry after ten errors" option, amoung other things. On the subject of the 2k buffer size. This is true ONLY for the protocol file transfer mode. It does not affect the terminal capture mode. It was done after NUMEROUS complaints from people with slower disk systems which took so long writing the 16k buffer out (and consequently closing that extent and opening the next in the directory) that they lost the next sector and several tries from the sender. In many cases this caused the transfer to abort. The 2k buffer was chosen MANY versions back (when the program was MODEM2) as an acceptable compromise between disk access speed and the improvement in receiving speed by putting the characters into the buffer instead of writing every sector (which was the way Ward Christensen's old original MODEM program worked) to the disk.
ABN.ISCAMS%usc-isid@sri-unix.UUCP (01/13/84)
Ref the little ~ character showing up sometimes in MDM716 -- I see the same thing in my earlier MDM's, and also in KERMIT and other terminal programs. Not all the time - just under certain conditions. It doesn't show up in my files, but appears to be something that went up to the host and echoed back to me. I believe I can delete it up on the host. Donno what it is - but appears to be harmless. David Kirschbaum Toad Hall