8086 Object Module Formats

Version 4.0

symbols. This restriction is not reauired by R&L, and is not enforced by it .

LOGICAL SEGMENT (LSEG) A contiquous reqion of memory whose

contents are determined at translation-time (except for address-

binding) • Neither size nor location in MAS are necessarily determined at translation-time: size, althouqh partially fixed, may not be final because the LSEG ~ay be combined at LINK-time to other LSEGts, forming a sinqle LSEG; location in MAS is usually determined

at LOCATE-time (althouqh some translators may produce Mabsolute~ object code, whose location is already determined).

FRAME - A contiguous region of 64K of MAS, beqinninq on a paragraph boundary (i . e . , on a multiple of 16 bytes). This concept is useful because the content of the four 8086 seqment reqisters define four

(possibly overlappinq) FRAME's; no 16-bit address in the 8086 code can access a memory location outside of the current four FRAME's.

An LSEG is constrained to be no qreater than fi4K, so that it

can fit in a FRAME. This means that any byte in an LSEG may be addressed by a l6-bit offset from the base of a FRAME covering the LSEG.

PSEG - This term is equivalent to FRAME. Some people ~refer MPSEG~ to MFRAME· because the terms MPSEG M and MLSEG d reflect the ~physicaln and Mlogical M nature of the underlyinq seqments.

FRAME NU~BER Every FRAME beqins on a paraqraph boundary. The Mparaqraphs· in MAS can be numbered 0,l,2, ••• ,~5535. These numhers, each of which defines a FRAME. are called FRAME NUMBERS.

PARAGRAPH NUMBER - This term is equivalent to "FRA,,.,E NUl'JfBER."

PSEG NU~BER - This term is equivalent to "FRAME NU~BER.~

PIC - acronym for Position Independent Code. A PIC module is a module

where load addresses and reqister initialization values are

specified relative to seqment and qroup bases. No fixups are allowed.

LTL - acronym for Load-Time Locatable. An LTL module is similar to a PIC module except that base fixups are allowed.

GROUP - a group is a collection of LSEG's defined at translation-time, whose final locations in MAS have been constrained such that there will be at least one fRAME which covers (contains) every LSEG in the collection.

The notation ~Gr A(X,y,Z)d means that LSEG's X, Y and Z form a arouo, and that the qroup's name is A.

The fact that X, Y and Z are all LSEG's in the same ~roup does not imply any orderinq of X, Y and Z in MAS, nor does it imply any contiquity between X, Y and Z.

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Intel 121748-001 manual