New Star Software Collection/NSS_Collection.iso/3-069 qemm 603/1.ima/QMANFEST/CH5.MAN

Text File | 1991-10-07 | 14.5 KB | 368 lines

Chapter 5

First Meg

 This chapter covers the information you need to know to make
best use of your first megabyte of memory. For DOS PCs, the first
megabyte of memory is very important. It is the area in which DOS
programs are run and the area in which your PC hardware is
controlled.

There are two areas of memory in your PC's first megabyte ~dash~
conventional and high memory. Conventional memory is the
contiguous memory, usually located in the memory addresses
between 0K and 640K, that is used to run DOS programs.
Conventional memory will be smaller if your PC has less than 640K
of memory. It may be possible to increase conventional memory by
64K or 96K ~dash~ if the contiguous memory area immediately
following the 640K is available.

High memory is the memory between the top of conventional memory
and 1024K (1MB). This area, like conventional memory, can be
addressed by DOS. However, this area has been traditionally
reserved by IBM for use by the system ~dash~ for the ROM BIOS
and hardware devices. As DOS programs have become larger, and as
you have need to run several programs at once, high memory has
increased in importance. The reason is that there are often more
memory addresses reserved than are actually being used. So there
are precious available memory addresses, usable by DOS, ripe for
the picking!

Note that your PC may not have actual physical memory for each
memory address in high memory. This physical memory may be
provided by the hardware configured for your PC ~dash~ for
example, memory provided by the ROM BIOS, by video adapters, or
by an expanded memory manager.

Because high memory has specific addresses reserved for adapters
and the system ROM, any memory addresses available may not be
contiguous. Since all DOS programs require that the memory
addresses in which they run be contiguous, high memory can not be
used to run large programs. Rather, unused or available addresses
in high memory must be used to run programs that fit within the
available block of high memory.

To use available high memory addresses (other than video
addresses) does require either EEMS or EMS 4 expanded memory
hardware capable of mapping into conventional memory, or an 80386
processor with an EMS 4 expanded memory manager. In both cases,
the memory manager can map 16K contiguous blocks of expanded
memory into unused 16K blocks of high memory.

The benefit of this capablity to you is that you can run network
drivers, mouse drivers, small TSRs, and even parts of DOS in high
memory ~dash~ thus leaving conventional memory for your large DOS
programs.

~Subhead~ First Meg Overview (FO)

 First Meg Overview shows you a map of the memory areas used in
your PC's first megabyte of address space.

 The map has two sections: the area known as conventional memory
(usually the first 640K of memory) and the area between
conventional memory and the first megabyte boundary, known as
high memory. This is nominally for hardware adapters and BIOS
ROM.

~Heading~ Introduction to the First Meg Map

 First Meg Overview shows you how you are currently using memory.
With this, you can:

~Item~ Find out the size of the largest program you can run in
conventional memory (Available),

~Item~ Find out how much of conventional memory is being used by
COMMAND.COM and TSRs (Program Area),

~Item~ Determine if there is high memory, designated as Unused,
where Manifest finds no ROMS or mappable memory~dash~but could be
mapped with memory. You do need EMS 4 or EEMS memory to use this
memory.

~Item~ See what high memory is available to be mapped by programs
using EMS 4.0 or EEMS. These blocks of memory (always a multiple
of 16K in size) are designated as mappable, or as the Page Frame.

~Item~ See what memory, designated as High RAM, is usable by
QEMM's or QRAM's LOADHI to load drivers, TSRs or parts of DOS in
high memory.

~Heading~ Understanding the First Meg Map

 To better understand the information reported in First Meg
Overview, familiarity with some of the other Manifest screens may
be helpful. For example:

~Item~ memory reported for DOS includes that of the DOS kernel
plus the memory added by statements in CONFIG.SYS. (Refer to DOS
Overview for details),

~Item~ memory reported as Program Area consists of memory used by
COMMAND.COM and any TSRs not loaded high. (Refer to First Meg
Programs),

~Item~ memory reported as Video Text/Graphics or Video ROM shows
the memory devoted to and/or used by your video adapter (See
System Adapters),

~Item~ memory reported as High Ram may have programs loaded
there. (See First Meg Programs)

~Item~ memory reported as mappable is under control of the
expanded memory manager. (See Expanded Memory Chapter)

~Item~ information on this screen can show you the potential
benefits of EMS 4 or EEMS memory if you currently have none, or
help you optimize your use of EMS 4 or EEMS memory if you do.
Unfamiliar terms used here are more fully defined in the Expanded
and QEMM chapters.

 Manifest examines memory and determines how each area has been
used. An area that it cannot assign a use for is labeled as
Unused. Typically, these areas could be used by an expanded
memory board and manager that had the necessary hardware and
software capabilities, and could then be turned into High RAM
with Quarterdeck's QRAM or QEMM.

~Heading~ Hints for DESQview Users

 DESQview users, running Manifest in a window, will see
information related to the configuration of the window's memory,
not the configuration of the PC's memory. This means that the
memory marked as Available is the amount of memory available for
use by programs running in the window, not by all programs on the
PC.

 Secondly, DESQview makes it so that all memory which is not
usable by programs in the window will not be included in the
window's known memory area. This makes Manifest report that
conventional memory ends not at the "real" end of conventional
memory, but rather at the end of the memory available to the
DESQview window.

 Finally, all areas marked as Mappable outside of DESQview will
be hidden from programs running in DESQview, and will be
designated by Manifest as Unused.

~Subhead~ First Meg Programs (FR)

 First Meg Programs shows you a map of what is loaded into memory
(excluding DOS and device drivers), and the areas of memory
available for use. If you are using Quarterdeck's QRAM,
QEMM-50/60, or QEMM-386, there may be a double line in your
display. If there is, it indicates the point where conventional
memory ends, and high memory begins.

 If present, the program map of high memory shows where memory
resident programs, drivers (i.e. network and mouse drivers) and
DOS FILES, BUFFERS, FCBS, and LASTDRIVE have been loaded by
QEMM's or QRAM's LOADHI. It also shows you available memory.

 You use this screen to:

~Item~ see what memory your programs are using. Often you will
see a separate area for the program's environment, and a separate
area allocated for the program's data.

~Item~ identify programs, currently loaded in conventional
memory, that could be loaded in high memory.

~Subhead~ Memory Accounting

 If Manifest cannot determine the name of your program or device,
it gives it a name. The name given is the memory address where
the program is running.

 Manifest excludes itself from its reports. Note that nowhere is
there reference to Manifest in the program map. The report's
purpose is to give you information about your programs as you
normally use them. Manifest will report itself if it is left
resident in memory.

 Memory Fragments: Every program, when loaded, is given an area
of memory known as an environment. These areas are shown
separately in this map. When Manifest shows small fragments of
available high memory, it is often because a program has released
its environment memory. These areas show up as available, but due
to their size are not particularly useful.

 The high memory shown by Manifest as Available can be used
either to load more of your TSRs, device drivers, and DOS data
into high memory or used by DESQview's XDV program to move parts
of DESQview into high memory.

~Subhead~ First Meg Interrupts (FI)

 First Meg Interrupts presents two detailed views of your PC's
interrupt vectors. The Interrupt Owners screen lists the
programs, drivers, and ROMs providing interrupt services,
followed by the interrupt numbers they service. The Interrupt
List screen lists the interrupts by their number, giving also the
name or purpose of the interrupt, its address, and the name of
the program, driver or ROM providing the service.

 These screens only show the most recent program which has the
vector. Other programs loaded earlier may also be servicing the
interrupt.

 On a color display, program and driver names are displayed in
cyan, while DOS and ROMS are shown in white.

 These screens provide technical information of use to
programmers and technical support personnel. If you are a non-
technical user, your ability to relay this information may help
to resolve some difficulty you are experiencing.

~Subhead~ Uses of First Meg Interrupts

 You use the Interrupt Owners screen to:

~Item~ determine what programs service interrupts, and which
interrupts they service,

~Item~ determine which interrupts are not being serviced (i.e.
the interrupt address is zero or the address indicates the ROM
BIOS default interrupt handler), or

~Item~ with Manifest in TSR mode, help you profile a program's
interrupt usage.

 Programmers may find these interrupt screens helpful:

~Item~ in determining conflicts among programs trying to provide
interrupt services,

~Item~ during debug sessions for locating the routines,

~Item~ for finding a "safe" interrupt to use, or

~Item~ as a quick reference to the interrupt services defined.

~Subhead~ Interrupt List

 The Interrupt List consists of sixteen screens that list
interrupts by their number. The list also shows the name or
purpose of the interrupt and the address and name of the program
providing the service.You display this list by pressing the F3
key when the Interrupt Owners screen is displayed.

 You can display any one of the 16 screens by entering Alt-X
where x is the first digit of the hexadecimal interrupt number.
For example, Alt-2 will display the screen containing interrupts
20 through 2F.

 You can use the Interrupt List to:

~Item~ learn what program is using an interrupt (for example, INT
16 if you have keyboard problems), and

~Item~ check whether the interrupt is in use by another program.

 Note: Due to the use of the interrupt vector area of memory as a
program stack during power up, few programs make use of any of
the later interrupt numbers available, and the contents of these
vectors are seldom meaningful. Consequently, Manifest does not
attempt to identify programs using vectors C0 to FF.

~Subhead~ First Meg BIOS Data (FB)

 First Meg BIOS Data screens present the data area in RAM devoted
for use by the ROM BIOS.

 This BIOS Data Area is an area of conventional memory used by
the system ROMs for keeping track of the state of the
system~dash~the keyboard, disk drives and video adapter cards.
The BIOS data area is 172 bytes of memory located just above the
interrupt vectors.

 Many application programs also reference, and some change, the
information contained in this memory area.

 Experienced PC users may find these screens helpful in a number
of ways:

~Item~ as a database reference of the BIOS data structure, and

~Item~ for quick access to port address values or the installed
hardware and memory size values.

 Experimenters and students may find these screens helpful in
confirming the effect of DOS and BIOS calls.

~Subhead~ Technical Hints

 PC's with an extended BIOS Segment. Manifest reports the
existence of the Extended BIOS segment at offset 0E. In other
systems, this location is assigned to a possible fourth parallel
port. If your computer displays only 639K of conventional memory,
this is an indication that the computer does have an Extended
BIOS Segment. IMPORTANT: QEMM-386 and QEMM-50/60 version 5
automatically relocate this data.

~Subhead~ Timings (FM)

 First Meg Timings provides memory access times for various
segments of the PC's first megabyte of memory.

 The purpose of this display is twofold:

~Item~ first, to show how fast your computer memory is relative
to a PC/XT, and

~Item~ second, to show the relative speeds of different areas of
memory.

 Use this display to:

~Item~ see the effect of a hardware memory cache, if you have
one,

~Item~ determine the effect of your PC's Shadow RAM,

~Item~ analyze the possible effect of upgrading memory boards or
chips,

~Item~ compare the speed of your standard memory with that of any
ROM or video memory, and

~Item~ see the effects of QEMM's ROM feature.

~Subhead~ Timing Insights

 Some computers have a hardware feature known as memory cache,
which can greatly improve the performance by effectively speeding
up the memory of the PC. A memory cache is extra-fast memory
which stores recently accessed data so that if it is accessed
again soon, it will be accessed from the extra-fast memory rather
than from normal memory. Since much of a computer's activity
involves accessing the same memory repeatedly, this technique
causes at least 50% and sometimes well over 90% of the computer's
memory accesses to be sped up. If your machine has a memory
cache, then Manifest will report its speed. This timing is the
most significant one for evaluating your machines's effective
speed.

 Slowest Memory: ROM memory, video adapter memory and other
adapter memory will usually be the slowest memory. Unanticipated
variations in any add-on memory you have will show up here.

 Variations in Speed: It is normal for your PC's speed to vary up
to 10% from one reading to the next. As long as the variances
between ratings is not more than 10%, no problem is indicated.

~Subhead~ Timing Insights (Continued)

 All ROM memory is slow. Because ROMs are usually 8 bit memory,
ROMs run at the same speed as 8088 memory when running on an
8088, half speed when running on a 80286 or SX80386, and slower
still if you are using an 80386 (an 80386 uses 32 bit memory, and
8 bit ROM).

 If you are using QEMM-386, you may use QEMM.SYS's ROM switch to
map your slow ROMs into RAM. If the timings test indicates that
all but your PC's adapter memory in your 80386 runs at full
speed, your ROM has already been mapped by the system. Compaq
computers and others do this.