File:	CHARM::[LOGG.AMS]DNL.DOC
Date:	12/5/86

	There is a new AMS fast download program available for public use.
There is no need to give up compatibility with old HEX files.  The new 
downloader will still support extended TEK HEX files.  To get the new 
downloader do the following:
	1. Burn 2 27128-2 EPROMs from the file CHARM::[LOGG.AMS]U55U56D128.LDA
	   starting at 4000 and ending at BFFF.  Label them LOGG-U55 and
	   LOGG-U56 with the current date.  Please label the outside of the
	   AMS so that we do not send the AMS out for service with these 
	   EPROMs.  
	2. Replace the new U55 and U56 EPROMs with the ones in the AMS.  They
	   can be found on the PCB connected to the ribbon cable.  On power
	   up you will notice that there are CRC errors.  Please ignore these.
	   When I know how to CRC the EPROMs I will release a new version.
	3. In your LOGIN.COM file define the symbol DNL.  Please see the DOWND
	   documentation if you need more information.  For example, it is
	   possible to tell DOWND to download several files at once.  More
	   importantly one can tell DOWND not to load all the uninitialized
	   data by specifying the starting and ending addresses.
		DNL :== MCR DOWND /DELAY=0 /RECORD=250 /ADD=start:end
	4. To use the new downloader, perform the following steps.  The AMS will
	   display a "." for each record read successfully.  The letter "X"
	   will be displayed when an transmission error occurs.  But don't 
	   worry because the downloader will ask the VAX to retransmit the last 
	   record.  I also suggest that the terminal, NOT the VAX, be set on 
	   WRAPAROUND so that the "." will be printed on the next line instead
	   of being lost off the right side of the screen.  This is done by
	   entering setup mode A and changing the second bit of the third nibble
	   from 0 to a 1 and then type control S to save this setting.
		>DNL				type this on the AMS as usual
		$ DNL filename.xxx	download filename.xxx
		....................		"." for each record read
		>				successful completion
	5. DOWND does not currently support symbol files.  This will change 
	   when the new LLF is released by Dave Shepperd.  To download symbols 
	   now it will be necessary to do a separate download using TEKHEX 
	   format in the following manner.  Note that the displayed data is 
	   the same as before except the leading "%" is not displayed.  This 
	   is how I can tell that the new downloader is present.
		>DNL				type this 
		$ TY filename.SYM		download just symbol file
		xxxxxxxxxxxxxx			data downloaded without the
		xxxxxxxxxxxxxx			 leading %
		>				successful completion


	If there are any problems report them to me at x1732 or via VAXMAIL at
CHARM::LOGG and I will try to correct them immediately.  If you have other 
ideas let me know so that I can try them out or document them here in this 
file.  For those of you that would like to improve on the download time even 
further.  The following can be done:
	1. To speed up communication to the VAX, have the Systems Group set the 
	   terminal to 8 bit NOPARITY.  It will also be necessary to change the
	   AMS too by typing "SET #12,0", "SET #22,0", and "SAV".  This will 
	   reduce downloading by approximately 1/11 (from 11 bits per character 
	   to 10 bits). 
	2. I have another version of the program that could download at 19.2K 
	   Baud but the download time is essentially the same as the download
	   time at 9600 Baud.  This leads me to believe that the 6809 excution 
	   speed is now the limiting factor in decreasing the download times.  
	   The current version of the program, at 9600 Baud, seems to send no 
	   XONs and XOFFs because it can fill memory as fast as the VAX sends 
	   data.  In any case, it would work for only those terminals named 
	   TXxx.  Do NOT have your terminal set to 19.2K Baud permanently 
	   because the AMS cannot currently handle that speed.  At 19.2K Baud,
	   I suspect the AMS is losing a character causing the download to 
	   hang.  So until the AMS software is upgraded I will not recommend 
	   this method.  
	   NOTE: the symbol files in TEKHEX format will abort on an error 
	   because there is no retransmission method for this file type.
	   NOTE: to temporarily use 19.2K Baud SET #20,#15 on the AMS and
	   SET TERM /SPEED=19200 on the VAX.  
	3. As a last resort, you can break the download data into several 
	   sections and load them separately.  This is only helpful if a small
	   number of these sections are being modified at any one time.


	The current performance of the new downloader is shown in the following
table.  Please note that your mileage may vary.  For your information, it takes
the VAX approximately 5 to 6 milliseconds to receive the ACK and start 
transmission of the next record.  For this reason, it is desirable to have the 
record size as large as possible.  There is a buffer in the AMS that holds 
the record sent by the VAX and I could not determine its size.  This means
I don't know how large a record it takes to blow up the AMS.  For now, it seems
to work fine with a record size of 250 and we cannot do much better with a
larger record size, so let's use that size until someone determines the real 
buffer size.
	TYPE TEKHEX.HEX		56.0 seconds with parity set at 9600 Baud
	TYPE TEKHEX.HEX		50.5 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=32	29.3 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=64	22.5 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=96	20.8 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=128	19.9 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=200	19.2 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=250	18.7 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=300	19.1 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=400	18.8 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=500	18.9 seconds with no parity at 9600 Baud
	DNL  TEKHEX.HEX/rec=infinte	17.1 seconds in theory at 9600 Baud