tether@mitlns ("STEPHEN_TETHER") (10/08/86)
Here is a translation of the MonST documentation from the German. Ron isn't
on the net, so I'll forward comments to him.
Steve Tether
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MonST.doc - Translation of manual for MonST monitor program
10/02/86 - Ron Sprunger
R & D Tech
74-050 Highway 111
Palm Desert
CA 92260
(619) 340-5900
Corrections 10/05/86 - Ron Sprunger
*** Introduction to MonST - Version 1.0 - 3/86 ***
Program by:
Matthias Meyer
Rosenwinkel 36
2380 Schleswig
West Germany
"Looking under the keys"
-------------------------
MonSt is a comfortable and powerful monitor program for the Atari ST.
The program is fully relocatable, and will run anywhere in memory, but
not on EPROM. It makes little use of GEMDOS, and has only one XBIOS call,
so it will work with all versions of TOS.
To use the program, you must have an eighty-character monitor, either
high or medium resolution only.
When MonST is started, it displays the block of memory which it has
occupied. The user should remember or write down these addresses in
order to avoid accidentally overwriting the monitor.
Use the program with care! You are working very close to the machine
itself, which means that careless memory edits can quickly crash the
computer.
a) Full Screen Editor
TOS unfortunately provides only keyboard-in and picture-out routines,
and not (as for instance the old Commodores) a picture-in routine. In
other words, the screen cannot be read easily to pickup the changes
which might have been made. For this reason, a 2000 byte buffer is used
to hold the screen text, making changes directly on the screen possible.
This text buffer lies just above the program code, and uses no RAM
outside of the p
rogram code area (except for the exception vectors -
see "V").
- The cursor can be moved all over the screen with the cursor control
keys (arrows).
- <RETURN> scans the current line, and updates memory accordingly. At the
start, periods or blank positions will be skipped over. (If someone
can make better sense than I can of the treatment of periods and blanks,
please let me know. - RS)
- <Backspace> erases the character to the left of the cursor, and shifts
the rest of the line to the left.
- <Delete> erases the character under the cursor.
- <Insert> opens an empty position.
- <Home> moves the cursor to the upper left corner of the screen.
- <Undo> moves the cursor to bottom left corner of the screen.
- <Shift-Clr> clears the screen.
- Other commands:
<Ctrl-RETURN> Jumps to the next line WITHOUT updating memory
<Tab> Moves cursor ten positions right
<Ctrl-I> Inserts a line
<Ctrl-D> Removes a line
<Ctrl-A> Deletes to end of line
<Ctrl-C> Abandons the edit - returns to desktop (!)
<Help> Redisplays screen from the text buffer
(see "O" command)
- The numeric keypad can be used for hex digits, "(" for "A", ")" for
"B", etc. You can use "." on the keypad for Backspace.
b) Monitor Commands
The most important commands are standard, most of the others follow
the convention of SMON for the C64. Lower or upper case may be used
(with exceptions).
Addresses are given and received as 6-digit hex numbers.
If two addresses are used to describe the same object, the second
address will be invalid.
Parameters in square brackets "[]" are optional and may be omitted.
- X
(Exit)
Leave MonST, if the "are you sure" question is answered with "y".
When the program is exited in this manner, the reserved memory
(about 12 KB) will not be released. The previously changed exception
vectors remain pointed to MonST (see "V"). For this reason, MonST
should be re-entered via a system error, such as violation of
privileged memory. (Otherwise, each invocation of the program creates
a new copy of MonST 12K higher in memory.) This is easily done in
ST-BASIC with ?peek(-1). If no register contents have been changed,
"G" returns you to BASIC. Other program errors can also be started
in this manner, but you should use the disassembler to examine the
position of the error, since the program counter may not be correct
after a buss error ("g" points in this case to exception number 4].
- R
(Register)
Gives the contents of the processor register, which can be changed
with the editor. The register contents will be given to the processor
with a GO- or Trace-Failure.
- G [05 0000]
(Go)
Starts a 68000 machine language program at address $050000. If no
address is given, the actual value of the program counter (PC) will
be used.
- M 05 0000 [05 0100]
(Memory)
Gives contents of RAM or ROM as a hex dump with ASCII to the right.
Stop and proceed slowly with <Space>. Other keys produce a faster
display. <ESC> stops the display.
In RAM, the hex dump can be changed with the editor. Empty positions
are ignored. The listing can be scrolled up or down when editing.
- K 01 e000 [01 f000]
(Kontrolle)
Displays 64 characters of text per line from memory. Control characters
(less than ASCII 32) will be displayed as periods. When editing, small
and capital letters will be differentiated, periods ignored. Otherwise
the same as "M".
- D fc 0008 [fc 0200]
(Disassemble)
Disassemble and list from $FC0008 to $FC0200 with machine code decoded
to opcodes. Changes are unfortunately only on the hex words possible,
since an assembler is not yet included in the program. This at least
allows easy modification of some operands. With the help of a 68000
opcode table and some patience, small programs can also be entered.
Since the structure of 68000 machine code is very complex, this part
of MonST is sadly somewhat buggy. Attention should be payed to the
following: It is not entirely inconceivable that a correct processor
command will be incorrectly decoded (although I have not found any
errors lately). If this should happen, please pass the information
on to me. In addition, illegal opcodes will not always be recognized
as such and flagged with "???". For example, code such as:
MOVE.W D0,#1234 or CLR.B 061234(PC)
is nonsensical, or illegal, but might not be flagged as such by the
program. For this reason, the disassembler can get out of sync (for
instance starting to disassemble on an operand instead of on an op-
code), and display relatively long stretches of garbage. Scrolling
the disassembler (as with "M" and "K") is useless because of this.
- >O {1,2}
Switch printer protocol in/out
0: Output to screen only
1: Centronics port
2: RS 232
- L filename.xyz, 05 0000 or
L"filename.xyz" 05 0000
(Load)
Loads specified data file. You must always give a load address!
- S filename.xyz, 05 0000 or
S"filename.xyz" 05 0000
(Save)
Writes the memory area to disk. If the file name already exist on the
disk, you will be asked "are you sure?".
- @ [fil??ame.*]
Shows a directory of the disk. If "@" is followed by a space, the
characters which follows will be interpreted as a search mask. "?"
wildcards a character, "*" wildcards remainder of filename or extension.
If the command is given without a mask, "*.*" will be used (all files
will be displayed). The display includes filename, size in bytes,
and filetype as follows:
00 - Normal File
01 - Write-Protected
10 - Subdirectory, not file
At the end of the display, the free allocation units of the diskette
will be shown (each 1024 bytes long).
- @\directory\
Specifies sub-directory or path. All further disk I/O will use this
path (Loads, Writes, Directories). Return to the root directory with
"@\".
- @B
Specifies disk B: as the working disk (A .. E).
The most important errors produced by disk I/O:
-1 General error
-6 Track not found
-8 Sector not found
-13 Disk is write-protected
-33 File not found
-34 Path not found
- F 01 0000 05 0000 41 42 43
F 01 0000 05 0000 "Digital Research"
F 01 0000 05 0000 44"igital "*"ese"61"rch"
(Find)
Searches byte-wise in specified memory. Hex digits and text can be
intermixed. An asterisk outside of quoted text specifies a wildcard
character. The addresses of matches will be given - use <ESC> to
break off the search.
- F "-****(a*)" 03 0000 [03 1000]
Searches for string in the disassembler listing from $030000 [to
$031000] - "*" is a wildcard character. This example searches for
all commands which use the "address register indirect with (negative)
16 bit offset" reference mode. <ESC> stops the search.
- O 07 8000 08 0000 01 02 03 (512 KB RAM)
O 0f 8000 10 0000 aa 55 (1024 KB RAM)
(Occupy)
Fill memory with specified long word value. If no value is given,
the default is 00. Check out the above commands for a 512 KB and a
1024 KB machine. The screen will fill with a fine point pattern -
pressing the <Help> key will restore the display.
- W 05 0000 06 0000 07 0000
(Write)
Moves memory bank $050000 - $05ffff to $070000.
- = 05 0000 06 0000
The memory bank starting at $050000 is compared with that starting
at $060000. The position of the first non-match will be shown.
- #491520
Convert decimal number to Hex. Max 2^32-1
- $00078000
Convert 8-digit hex number to Decimal.
- %10101011
Convert 8-digit binary number to decimal.
- ?z xxxxxxxx yyyyyyyy
Simple calculator, where z = :
+ : 32 bit addition (2 8-digit hex numbers follow)
- : 32 bit subtraction
* : 16 bit multiplication (2 4-digit hex numbers follow)
/ : Divide 32 bit number by 16 bit number
& : 32 bit logical AND
: OR
! : EXCLUSIVE OR
- V
(Vectors)
Displays the vector table from low RAM ($0000 to $3fff). Addresses
marked with an asterisk point to the BREAK-entry into MonST. The far
left-hand byte gives the exception number. Stop display with <ESC>.
Upon startup of MonST, the exceptions number 2,3,4,5,6,7,8,9, and 32
(buss, address error, illegal opcode, divide-by-zero, CHK-error,
TRAPV-error, privilege violation, trace-mode, Trap #0) will be diverted
to the register pointers. Should one of the "errors" occur, an attention
character and a blinking cursor will appear in the lower left corner of
the screen. The purpose of this is to avoid too-quickly destroying the
contents of the screen.
Pressing <ESC> releases the register display. A keypress produces an
announcement of the exception number, and the processor register will
be pointed to the location of the break. If it is a buss or address
error, the information placed by the CPU on the stack will not be
lost. It is this status word, holding the flags in the lower 8 bits,
which describes the error more exactly, including the target address
which produced the error and the last opcode acted on. A buss error
can easily arise, if you try to access memory not implemented in
hardware, or to write to ROM. You must be carefull not to set the
stack pointer too low, thereby destroying something. Be sure to
restore it to the appropriate value.
- TS 05 0000 05 0010
(Trace Stop)
The program will be started at $050000 and will break when $050010
is reached. This function uses the Trap #0 opcode, which is installed
at the stop address before beginning execution. The machine instruct-
ion from that location is saved and restored after execution.
- TW [05 0000]
(Trace Walk)
Opcodes starting at $050000 (for example) are executed one at a time,
with the help of the trace-bits in the status register. The screen is
split into two windows: in the upper, the applicable processor
is shown, and in the lower is the running program. The next opcode
is displayed in the second-to-last line (pointed to by the current
program counter). On the bottom line is a small menu, to remind you
of additional possible functions:
<Space> Executes the next instruction
<ESC> Aborts
<C> Does the same as <Help> usually does (separates characters
or graphics written to the graphics screen from other
programs).
<S> Executes a sub-program in real time from beginning to
end (to the RTS opcode).
<E> Does the same for an exception handler (to the RTE opcode).
For the last two, the stack pointer must be the same at the end of
the sub-program as it was at the beginning. An example: By stepwise
execution, you come to an error Trap #1, which calls GEMDOS. In order
to run this program all at once, you press <Space> and see in the
next-to-last line "BTST #5,(a7). This is the beginning of GEMDOS.
Now you can press <S>, and GEMDOS will do its work undisturbed. The
next command after the TRAP #1 will be shown. <E> can only used with
the supervisor bit set. If no return address is on the stack, the
program may run off into never-never land.
This all sounds very complicated, but with practice it goes smoothly.
"TW" works in ROM as well as RAM. Single-step execution lends itself
especially to exploration of complicated calculations made by the
CPU.
With the trace-bit set, a test program will not crash due to conflict
in the status word, so that a command such as "MOVE #2300,SR" can
be traced at your leisure.
- TB 05 0010 000a
(Trace Break) - parameters are address and word
A break point will be set at $050010 for fast step mode. Upon
reaching the address for the 10th time, the program will be interrupted,
and single-step mode will begin.
- TQ [05 0000]
(Trace Quick)
Fast step mode is only for use in RAM, and is used in conjunction
with TB (see above). These functions lend themselves to convenient
exploration of the operation of loops.
- TA 05 0000 0001 0000
(Trace Amount) - takes address, longword parameters
Starting at $050000, 2^16 machine instructions will be executed,
though with somewhat limited speed. All sub-programs will be
counted, as well as group two exceptions (TRAP's, CHK, Division
by zero). Up to 2^32-1 instructions can be counted (4.3 billion).
In addition, the program may encounter instructions which set the
trace bit back! May be used in ROM.
c) The Disk Editor
The disk editor is invoked from MonST with "Z". It needs a 512
byte buffer, whose absolute address may be specified ($050000 is
recommended, or somewhere in the middle of free RAM).
All disk I/O is done on drive A: (!)
- X
(Exit)
Exits the disk editor
- P
(Page)
Toggles the disk side, 0 or 1, with the result displayed.
Use ONLY on double sided drives!
- B
Change the buffer address (restart the disk editor)
- M
Show the contents of the buffer. The contents may be edited.
- R 01 03
Read sector 03, track 01 (hex)
Only "R" and "W" specify the actual track and sector numbers.
- W 01 03
Write the buffer contents to sector 03, track 01 (hex)
- +
Read the next sector
- -
Read the previous sector
In the disk monitor, scrolling text up/down is also possible. The
sector buffer may also be accessed from the machine monitor.
---------------------- The End (Das Ende) ------------------------
Note from translator:
The above is a fairly literal translation of the manual for
MonST as provided on BIX by Jim Omoura. The translator believes
that the translation is accurate, but does not have the working
program to check points of operation. I take NO responsibility
for the accuracy of the above document.
Ron Sprunger (BIX "sprung")
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