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56
Assembly Language Fundamentals
Storage
Modules
When assembly converts a source module into an object module, there must be a place to keep
the object module. That is the function of the ICOM region.
You were introduced to the ICOM region in Chapter 2 in connection with the loading and
storing of modules. It is also used to hold modules which are created through assembly. Once a
module has been assembled, the object code appears in the ICOM region just as if you had
loaded it from mass storage.
Variables
Within a module, you may want to set aside one or more words of memory for your use. For
example, you might need a location to store a variable, or keep a counter, or save a register.
This is done with the BSS pseudo-instruction -
' ... ' ' .... ' .... {number}
.\M..!· .•••.
t ....
..1
where {number} is the number of words to be set aside. {number} can be any absolute expres-
sion, provided the expression evaluates to a positive integer (see "Symbolic Operations"
below).
This kind of storage is part of the object code and is set aside "in-line". This means that
wherever it appears in the source, the storage appears in the same relative location in the object
module.
For example, suppose a module contained the following source lines -
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