Comments; Syntaxing The Source - HP 9835A Programming Manual

Assembly Language Fundamentals 53
This can be a nuisance in some instances during program development. Many programmers
use labels almost exclusively and rarely consider the line number when using the editor to
change a line. For instance, in the above, they would not be used to saying, "EDIT 100" to get
at the line in order to change it. They are more used to saying, "EDIT Rumpelstiltskin". A way
for them to do it would be to change the line to -
Note that, as the example demonstrates, the name can be the same in the BASIC label as in the
source. This takes advantage of the fact that BASIC and the assembler are unaware of each
other's labels. The names do not have to be the same.
Comments
As with any BASIC line, a comment may be included by simply adding an exclamation point
( ! )
and typing your comment after it. Since you have a total of 160 characters for a line, your
comment may fill up the remainder of the 160 characters left after the rest of the statement has
been provided (line number, ISOURCE keyword, label, action).
Syntaxing t'he Source
When you are creating your source program, you are either entering· it from the keyboard or
retrieving it from mass storage (LINK or GET). In either case, as the statement is entered (the
8
key on the keyboard is pressed or a record is read from mass storage), the operating
system takes note of any use of the keyword ISOURCE. When a line has this keyword, the
operating system turns over the remainder of the line following the keyword to the assembly
system. The assembly system, then and there, checks the syntax of the source.
By checking the syntax at the time of entry of the statement, a considerable amount of proces-
sing time is saved when the time comes to assemble the source into object code. In addition, it
gives you, as the programmer, immediate feedback when a syntactical error occurs. You do not
have to wait until assembly time just to find out that you misspelled NOP.