SOME INFORMAL NOTES ON RES86   V2.2
		   W. Earnest  11/20/84

	Here are a few of the changes made to a venerable 
program that has served well for many. Written by Ward 
Christensen for the 8080, it was modified several times for 
the Z-80, and had many other features added. Recently I got 
a copy that had been converted to the 8086, and naturally 
started to see what I might add. Here are the results to 
date. It seems useful (to me) and may help someone else.

	To bring it up to a level similar to recent 8080 
and Z-80 versions, an online HELP screen was added, multi- 
column listing of the control and symbol tables, and 
optional file load and save with the .ALL key to save on 
typing. Also, the 'ALL' option is automatic if the filename 
is given on the command line (assuming .CMD for the image).
Automatic deletion of replaced symbols was added, as well 
as protection against accidental duplication of symbols. 
The comment capability was expanded to include both 
appended comments and ones that replace instructions. Many 
of these ideas were lifted from ZESOURCE and other such 
variations of the original RESOURCE.

	When I started, RES86 loaded the whole image file 
as one block, with no processing. I extract the header 
record data and place it in tables, then load the rest so 
the image starts at relative 0, with no 80h offset. Each 
segment is recognized, and the size, starting point, and 
offset retained for use and display with the '?' function.

	An added flag byte to each entry of the symbol 
table retains the segment and size information of the 
symbol, much as done by the assembler. This is used to 
decide whether to append a colon, and to resolve usage 
where offsets of 2 symbols in different segments are the 
same. This byte is forced to a printable ASCII value for 
saving and restore in the .SYM file, and is displayed in 
the symbol table listing. When defining a symbol, the 
offset is assumed to be in the current segment, and will be 
copied from any symbol being replaced, or the user may set 
it with the syntax: Ennnn,.symbol,m   where m is the ASCII 
character desired.

	To control the segment being worked on, I added the 
syntax of segment registers to several commands, such as 
the D, L, ;, O, C, and others. Used as in the following 
example:  DCS:0,7F   it selects the segment to be 
processed, sets the "current" segment, places the segment 
letter in the command prompt, and modifies the offset to 
match the base of the right segment. If working with an 
8080 model file, it recognizes the fact and makes all 
segments equivalent.

	The control table was handled a bit differently. 
Rather than add a byte to each entry, the control table 
internally uses addresses as if the file was one large 
block, and the routines that address it correct by the 
difference between the current segment base and the file 
base. The 'C' command will display the whole table while 
one of the form:  CDS:  will show only those control 
entries belonging to the data segment, corrected in value 
to be relative to the segment base. Entry of a control 
value is also done relative to the current base, the 
correctin being internal.

	A few bugs were cleaned up in the instruction 
disassembly area, opcodes for the 80186 added (not yet 
finished), and one change made that may not agree with all. 
I prefer instructions of the form:  MOV reg16,constant
to use symbols where the offset matches, rather than a hex 
value. I find it easier to remove excess symbols than to 
post-edit constants to symbols, and find it more error-free.
If you don't agree, feel free to change it back (at the 
KIND03 area of the code).

	Well, I'm probably not done, but maybe someone else 
can add some more, or make use of it at this point. If you 
have any good ideas, please pass them back, so it can 
continue to improve. Don't expect it to be bug-free,
everyone needs a challenge.

			Bill Earnest, Allentown PA SYSOP
			(215) 398-3937 RCPM 24hr
			(215) 398-1634 Voice before 10PM
			RD 1, Box 830, Orefield PA 18069