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MANIFEST.MFT
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1990-04-23
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These charts were created by Quarterdeck Office Systems, using
Quarterdeck's Manifest program, in order to compare 16-bit
expanded memory boards from different manufacturers. All boards
used in this comparison were tested on a 6 mHz IBM AT with a VGA
video card and 256K of active memory on the motherboard. We did
not test boards that could not map pages of expanded memory at
least as far down as 256K (segment address 4000H).
Here is a brief description of the Manifest reports displayed:
System/Config: The parameters on the memory manager's CONFIG.SYS line
give some indication of how much effort may be required to configure
the memory manager for use with DESQview, although some memory
managers' setup programs place these parameters automatically. When
we knew how to do it, we reduced the number of expanded memory handles
provided by the manager to 16, a number adequate for most users'
purposes; this reduction both decreases the RAM taken up by the memory
manager and improves some benchmark timings. The presence of the
DESQview driver QEXT.SYS in the CONFIG.SYS indicates that we were able
to configure the board so that it provided a small amount of extended
memory as well as expanded memory - a very important feature for
DESQview users.
Expanded/Overview: More than 16 total EMS handles in this section may
mean that the driver's size and performance could be further
optimized, as discussed above. The existence of real alternate maps
is an important feature for DESQview users who want to run high-speed
communication programs in expanded memory.
Expanded/Timings: These figures are to some extent dependent on the
speed of the RAM chips on the memory board, but an unusually low
figure may indicate that the manufacturers have chosen to slow down
the memory that they map between 640K and 1024K.
Expanded/Pages: The more " + " signs (indicating mappable areas below
1024K) visible on this map, the bigger the program that can be run
inside DESQview. All boards tested allow the mapping of expanded
memory pages between segment addresses 4000H and A000H (256K-640K).
As these tests were done on a VGA system, the most pages above 640K
that any expansion board can be expected to map is four: one at
B000H, one at B400H, and two between C800H and E000H. 80286
computers do NOT allow the use of the E000H area by expansion
boards; an 80286 memory management unit on the motherboard, like
an 80386 memory manager, can access the E000H area and provide
four more mappable pages.
Expanded/Benchmark: Low timings here indicate superior performance in
the handling of expanded memory calls. All rows of figures except the
first row represent the time required to complete various EMS
functions; the first row (Timer Interrupt Latency) indicates the
amount of time that interrupts are locked during the different EMS
functions. Which figures are most significant depends on what you do
with expanded memory; more information is available in the Manifest
manual.
DOS/Drivers: The size of the driver labeled EMMXXXX0 indicates how
much conventional memory the memory manager takes up. This figure can
sometimes be modified by changing the number of EMS handles, contexts,
and names provided by the memory manager.