Jan 152018
 
Memory control block mapper. Version 1.10.
File TMAP110.ZIP from The Programmer’s Corner in
Category System Diagnostics
Memory control block mapper. Version 1.10.
File Name File Size Zip Size Zip Type
TMAP.COM 6020 3703 deflated
TMAP.DOC 3818 1435 deflated

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Contents of the TMAP.DOC file


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TMAP v1.10, Memory Control Block Map (c)1987,88 by MagicSoft, Inc.

This SHAREWARE Program may be freely distributed. If you
feel that this is a useful program, send $15 to:

MagicSoft, Inc.
125 E Prairie
Lombard, IL 60148

Usage: TMAP [/{nua}]

Where: "n" specifies NON-resident mode.
"u" includes vector 80-FFh.
"a" excludes Address for Hooked Vectors.

The "U" and "A" options were added for compatability
with TMAP versions before 1.10.


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Title Definitions
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MCBMemory Control Block. This is a 16 byte header that DOS
adds when a memory request is made (DOS Function 48h).
The format of a MCB is as follows:

Offset LengthMeaning

0byte4D = Normal MCB
5A = Last MCB in chain
(NOTE: 4D and 5A are ASCII M and Z,
which are the 1st 2 chars in an EXE
file. MZ are the initials of one
of the authors of DOS.)

1wordPointer to owner of the MCB. This is
the program who requested the momory block.
COMMAND.COM allocates all memory above
the last TSR program installed and will
free it when it EXECs a program (DOS
function 4Bh).

3wordParagraphs of memory in the block.

4-15reserved

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AddrAddress of allocated memory (always 16 bytes greater
than the MCB).

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OwnerPoints to the memory address of the program that
allocated the memory. If this field is blank, then
this is a program and not an allocated block of memory
and the Description field shows the name of the program
that is loaded.

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BytesAmount of memory allocated to this MCB. This is the
value at offset 3 in the MCB header converted to
bytes instead of paragraphs.

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Description

This field holds a program name (either a TSR program or the
program that is currently executing) or one of the
following:

Untitled

This is a program that does not have it's name in it's
environment. COMMAND.COM is one program that does not save
it's name and will appear as Untitled.

???, Missing Env

This is a program that no longer owns the block of memory
containing it's environment (offset 2Ch in it's PSP). In
other words, the MCB pointed to by 2Ch does not specify
the same owner or has been freed (see below).

Owned Memory

States that this MCB is owned by the program pointed to
in the OWNER field.

Environment

This is an environment (PATH=, COMSPEC= etc...) owned
by the program pointed to in the OWNER field. Each
program loaded has a copy of the previous environment
allocated to it.

Free

This MCB is owned by no one. The word at offset 1 in the
MCB header contains a 0.

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Hooked VectorsThis is a list of all/any 80x8x INT vectors that
point to an area inside of this MCB. Some vectors
(nornally those in the range of 80-0FFh) are
un-initialized and TMAP may report that they
point to a program that may not have assigned the
interupt. The /U option was added in version 1.10
to avoid this hastle.

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