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2021-04-15 11:31:59 -07:00
AST RESEARCH TECHNICAL BULLETIN TB-0177 6-4-86
REX.SYS MEMORY ALLOCATION AND IBM XT MODEL 516089
While testing was being conducted on the Model 516089 (new) IBM
PC-XT, a possible discrepancy was observed with REX.SYS (Extended
Memory Emulator). Two identical XT's with the same
configurations were used. Both XT's had subdirectories
containing the REMM.SYS and REX.SYS files. Both XT's contained
CONFIG.SYS files with the proper paths specified to REMM.SYS and
REX.SYS.
One XT worked properly and allocated the specified amount of
memory to REX.SYS.
The second XT is where the discrepancy was noticed. When REX.SYS
is invoked from a subdirectory, regardless of how much memory is
allocated to REX.SYS, it will only accept 64K bytes of extended
memory emulation (REX). However, when REX.SYS is invoked from
the root directory, the amount of memory allocated is equal to
the amount specified.
If this problem is encountered, it is suggested to put REMM.SYS
and REX.SYS in the root directory.