------------------------------------------------------------------------------- S.I.M. System-Independent Monitor Release 4, Version 1.81 Copyright © 1990-1993 by Stefan Walter ALL RIGHTS RESERVED ------------------------------------------------------------------------------- CONTENTS ======== 1. Introduction ==================== 1.1 SIM v1.81 1.2 Disclaimer 2. Getting Started with SIM ================================ 2.1 What is SIM? 2.2 Requirements and Limitations 2.3 Commodores Guidelines for 'Banging the Hardware' 2.4 Configurating SIM 2.5 The SIM Binary 2.6 Display Usage 2.6 Keyboard Usage 2.7 Mouse Support 3. Command Window Usage ============================ 3.1 Editing functions 3.2 Command Line Buildup and Execution 3.3 Command List Explanations 3.4 Memory Display and Related Commands 3.4.1 Hexdump 3.4.2 Asciidump 3.4.3 Disassemble 3.4.4 Copperlist 3.4.5 Print Text 3.4.6 Bitplane View 3.4.7 Hear Memory 3.5 Memory Editition Commands 3.5.1 Edit Memory 3.5.2 Assemble 3.5.3 Transfer Memory 3.5.4 Occupy Memory 4. Debugger Window ======================= 5. Assembler and Calculator ================================ 5.1 Assembler Usage 5.2 Calculator Usage 5.3 Data Lines 5.4 Disassembly Search Pattern 6. Safety Features ======================= 6.1 Warnings 6.2 Selfprotection 6.3 The External Interrupt Handler 7. Advanced Features ========================= 7.1 When SIM Fails... 8. Appendixes ========================= 8.1 Bibliography 8.2 Acknowledgements 8.3 Registered Users 8.4 Contacting Me... ******************************************************************************* 1. Introduction ******************************************************************************* 1.1 SIM v1.81 ================= Congratulations! You have just obtained a copy of the fourth release of SIM, a hardware oriented, high performance 680x0/688xx monitor and debugger for the Commodore Amiga. SIM is distributed under the concept of shareware. In other words, you are allowed to get a copy of it and to give it to anybody else. If you find this program good and if you keep using it, I would appreciate if you send me a contribution. For 15$ you will be registered and you will recieve support, in case of errors you may find, you will obtain a fixed version, and you get the next major release of the program. 1.2 Disclaimer ================== This program is provided "as is" without warranty of any kind. The entire risk of using it is to the user himself. In no event I (the author) will be liable for direct or indirect damage, loss of data or criminal actions done due to the use of this program. If you do not agree with this, you may not use SIM. ******************************************************************************* 2. Getting started with SIM ******************************************************************************* 2.1 What is SIM? ==================== SIM is a very powerful debugger and monitor. It was designed to work under all circumstances and especially to supervise rather unconventional programs which do not make much use of the operating system or do completely disable it for a more or less long period of time. It is intended for people who need to debug games, demonstration programs and even other operating systems on the Amiga. It fully supports the 68000-68040 processor range, the 68881/2 FPU and the 68851 MMU. SIM works below the operating system and does not interact with any of its facilities or routines. It disposes of ways to enable you relatively comfortable debugging of any piece of machine language. Be it a task list manipulating routine, an interrupt or direct access on hardware like disk drives or the blitter, routines you can't trace with an ordinary system based debugger. There are practically no limits, you can invoke SIM at any moment and it will pop up and work properly. SIM will do as less changes to the software and hardware (RAM, custom/cia registers) as it can. When you exit SIM, it will try to leave everything the way it was when SIM was started. SIM does neiter use blitter nor copper, so any 'interrupted' program can continue to run with no defects due to a call to SIM. SIM will be very useful for you if you need to debug programs belonging in the cathegories described above. If you only need to debug 'ordinary' programs with no critical or nonmultitasking routines, you are better served with a full system debugger. There are plenty of good debuggers of that kind available, also in the Public Domain. 2.2 Requirements and Limitations ==================================== SIM currently has certain problems with all kinds of graphic cards. Its display will only appear on a monitor connected to the RGB port of the Amiga. To use SIM efficiently, detailed knowledge of the AMIGAs hardware, the MC680x0 processors, their coprocessors and assembly language is ABSOLUTELY neccessary. If you lack this knowledge, get Commodores 'Amiga Technical Reference Series' and Motorolas documentations of the 68000 family. 2.3 Commodores Guidelines for 'Banging the Hardware' ======================================================== Accessing the hardware registers of the Amiga directly has been allowed by Commodore until the AA chipset was introduced. Now, to enssure compatibility of programs to new Amiga models and chip sets, accessing the hardware, especially the registers concerning display, is strictly prohibited for normal programs. SIM however needs to access those registers directly since its concept was *not* to use any functions of the OS. Therefore SIM will work on all existing Amigas but it is not guaranted to work on whatever comes after the A4000. In any case, an update of SIM which will be capable of handling any possible new chipset will be released as soon as new Amiga models are on the market. 2.4 Configuring SIM ======================= 2.5 The SIM Binary ====================== SIM is not an executable. It has no hunk structure and hence cannot simply be started from CLI or Workbench. It is a simple file containing fully PC relative code that needs no relocation. It can be located somewhere in the memory or included in any program that needs a built-in debugger while developing and just has to be invoked when needed. The advantages and possibilities of this concept are discused in a later chapter. SIM keeps its own dataspace within itself, so it is currently not possible to locate SIM in ROM/EPROM or in otherwise write protected memory. 2.6 Display Usage ===================== SIM builds up a one plane high resolution display, either interlaced or not. When you use PAL it has 640x256/512 pixels, in NTSC mode 640x200/400. Expressed in characters this means 80x32/64 for PAL, 80x25/50 for NTSC. SIM contains a full ASCII charset, which, by default, is the same as Kickstart 2.04 topaz 80. The display is seperated into three parts: The head line. It contains the program title, the entry reason and a signal field for warnings. It is also used for input of options and data used by certain shortcuts, and for keyboard restoring when leaving SIM. The command and debugger window. The command window serves for execution of commands, the debugger window to display the register set and one or multiple areas of memory. What is in the command window is stored when exiting SIM and available again when invoking SIM again. The bottom line. It contains a field for status and error messages and the startaddresses of SIM in memory, the plane, the backup for it and the work memory. 2.7 Keyboard Usage ====================== SIM contains two complete keymaps for unqualified, shifted, alternated and shifted & alternated keys, one custom that can be selected when configuring SIM and one US. The keymaps are adapted one-on-one from the international keymaps distributed by Commodore on the Workbench disk except that there is no 'dead-key' support. The user can toggle between US and custom keymap using the shortcut. To enter a character with ascii value from 0 to $1f, press and a key with ascii value from $40 to $5f, i.e. for the ESC character. To enter a character with ascii value from $80 to $9f, press and a key with ascii value from $60 to $7f, i.e. for the CSI character. Note that SIM makes a difference between keystrokes and function keys that normally have assigned the same ASCII value. Entering is a character and does not have the effect of pressing the key. This way it is possible to include any CTRL chars in expressions. Key repeat speed is 1/50th (PAL) or 1/60th (NTSC) of a second, key repeat delay is 5/2 or 1/3 of a second. Both can't be modified. The keypad is not used for movement, only for numeric input etc. 2.6 Mouse Support ===================== SIM supports the mouse for different operations. It is not vital to have the mouse connected, it is only used for features that enhance comfort. The mouse pointer is a little arrow, smaller than the regular mouse pointer. SIM doesn't use a sprite for it but copies the pointer directly in the plane. Therefore it may flicker sometimes. Speed is comparable to setting 1 or 2 of the normal preferences. Double click timeout is 1/2 of a second. The pointer automatically disappears as soon as you press a key or SIM is busy doing output on the screen. ******************************************************************************* 3. Command Window ******************************************************************************* 3.1 Editing Functions ========================= The command window is one of the two windows SIM has. It is used to execute commands likely to a CLI window of Amiga DOS with the difference that it's not line oriented but acts as a whole page. The cursor can also be moved up and down, enabeling reuse of previous commands and output. When typing, normally all text goes to the monitor window. SIM either uses insert or overwrite mode, depending what the user selected with the shortcut , default is overwrite. The command window is basically a text buffer. One can simply enter a character at any position in it. If the cursor would go below the bottom of the window by pressing in the bottom line, the entier buffer scrolls one line up. There is also no line wrap, a command line starts at row 1 and ends at row 80, the cursor will not switch to the next line when it reaches the right margin. The contents of the command window are stored within SIM and are available again at its next invocation. For editition of command lines and cursor movement, the following basic functions are assigned to function keys: - The cursor can be moved left and right by either pressing or . - The cursor can be moved to left margin by pressing . - The cursor can be moved to the end of the text line, that means to the space after the last char that is not a space in the line or to the last char if the line is full, by pressing . - The cursor can be moved one line up or down by either pressing or . - The cursor can be moved to the first or the last line in the window by pressing either or - deletes the character the cursor is on and shifts all chars right of it one left and inserts a space at row 79. - moves cursor one left and deletes that char. - inserts a space at the position of the cursor, shifting all chars right of it one right. - replaces char on which the cursor is by a space and moves cursor one left. - will clear the visible part of the command window and put the cursor in the left upper corner next to a period. - will clear the line in which the cursor is, put a period in row 1 and the cursor in row 2. - copies the last executed command line in the line of the cursor. - copies the line of the cursor in the command line buffer. It can then be inserted anywhere with . - will execute the commands in the line the cursor is in. - clears the part of the command line left of the cursor and executes it. - executes only the first command of a command line and ignores the rest Additionally to these, the following function keys also have a direct effect on the window: - activates the online help system. - goes one step back in command history and fills the line of the cursor with the current history command string. - goes one step forth in command history. If there is no newer command string, the line is cleared. SIM remembers the last command lines executed. The last two shortcuts are used to put an earlier executed command line back in the current line. The mouse can be used to position the cursor by clicking on the place where it must go. Snap functions described in a later chapter are also supported. 3.2 Command Line Buildup and Execution ========================================== A commad line in general looks like this, where is a command keyword and can be whatever: . : in an empty line with no command in it, SIM will execute the last command without arguments. This applies to all dump commands, trace commands and certain others. Commands are case sensitive. Rarely used or dangerous commands consist of multiple characters or are upper case. 3.3 Command List Explanations ================================= In the helppage and the explanations, the following abreviations are used for options: - s start address/seek - e endaddress - a address - t destination 'target' address/track - i assembly instruction(s)/fragments - d data - c text - n decimal number - x hexadecimal number - m mask - r register - p plane/period - b backup/buttons/block - ? calculator expression - f file - j advanced options Arguments in '[]' brackets are neccessary, leaving them away causes an 'argument missing' error and aborts command execution. Options in '()' are optional and can be left out. Chars in '{}' brackets are optional and serve as flags. Because space in SIM is limited, the help pages tell only the basic syntax of a command and its char sequence. The following list contains detailed information about each command. Commands for similar purposes are grouped together. 3.4 Memory Display and Related Commands =========================================== All dump commands share the same syntax. They also all use the memory paging and only display memory that is declared, use full charset if desired and 24 or 32 bit addresses. All commands use the actual address if no start address is specified. Refere to the appropriate section for details. 3.4.1 Hexdump --------------- Usage: m (s)(e) Displays the chosen clip of the memory as hexdump with asciidump, 16 bytes per line. If editable dump is on, a colon is put at the start of the line, enabling editing the memory by changeing the dump and pressing in the changed line. Memory that is not defined and hence not readable is represented by asterixes in both hex- and asciidump. Asciidump uses the full charset if this is enabled. If the chosen area's length is not a multiple of 16, it is rounded up to the next multiple of 16. m [s][e] Display hexdump from s to e. m [s] Display 8 lines hexdump from s. m Display 8 lines hexdump at actual address. Example: .m -20 !+37 :ffffffe0: **** **** **** **** **** **** **** **** ;**************** :fffffff0: **** **** **** **** **** **** **** **** ;**************** :00000000: 0000 0000 00c0 0276 00fc 0818 00fc 081a ;.....À.v.ü...ü.. :00000010: 00fc 081c 00fc 081e 00fc 0820 00fc 0822 ;.ü..ü...ü. .ü." . 3.4.2 Asciidump ----------------- Usage: a (s)(e) Displays the chosen area of the memory as asciidump, 64 bytes per line. If editable dump is on and full charset used, a '`' char is put at the start of the line, enabling editing the memory by changeing the dump and pressing in the changed line. Memory that is not defined and hence not readable is represented by asterixes. The entier charset is used if this is enabled, else CTRL chars are represented by a period. If the chosen area's length is not a multiple of 64, it is rounded up to the next multiple of 64. a [s][e] Display asciidump from s to e. a [s] Display 8 lines asciidump from s. a Display 8 lines asciidump at actual address. Example: .a -80 80 ffffff80: 'N.J.l..."*.ìp(j..N.NÖNq...............¬.......È...Ì...É...p...8 ' ffffffc0: '...@...Î...h...Í...°...Ê...|...Ë...T...Ñ.&}³....?À............. ' 00000000: '.....À.v.ü...ü...ü..ü...ü. .ü.".ü...ü.&.ü.(.ü.*.ü.,.ü...ü.0.ü.2 ' 00000040: '.ü.4.ü.4.ü.4.ü.4.ü.4.ü.4.ü.4.ü.4.ü.4.ü...ü.â.ü...ü.l.ü.ú.ü.@.ü..' . 3.4.3 Disassemble ------------------- Usage: d (s)(e) Displays the desired part of the memory as 680x0/688xx disassembly, one instruction per line. If an endaddress was given, the command ends as soon as after a line, the actual address is greater or equal to the endaddress. If no endaddress given, memory for 8 lines is disassembled. If editable dump is selected, a tilde is put at the start of a line enabeling to assemble to memory by changing an instruction in the dump and pressing . There are four possible dump forms, explained in the apropriate chapter. Instructions which are no pure 68000 code are marked with '?!'. Memory that is not defined and hence not readable is represented by asterixes in both disassembly and opcode. d [s][e] Disassemble from s to e. d [s] Disassemble 8 lines from s. d Disassemble 8 lines at actual address. Example: .d -2 10 ~fffffffe: **** * ~00000000: 0000 >ori.b #0,d0 ~00000004: 00c0 dc.w $c0 ~00000006: 0276 andi.w #$fc,$18(a6,d0.l) ~0000000c: 00fc *dc.w $fc ~0000000e: 081a btst #4,(a2)+ ~00000012: 081c btst #4,(a4)+ . 3.4.4 Copperlist ------------------ Usage: l (s)(e) Displays the desired area area of memory as copperlist disassembly, one instruction per line. Memory that is not defined and hence not readable is represented by asterixes in both opcode and disassembly. Copperlist instructions that are not pure are marked with '?!'. If the chosen area's length is not a multiple of 4, it is rounded up to the next multiple of 4. l [s][e] Display copperlist from s to e. l [s] Display 8 lines copperlist from s. l Display 8 lines copperlist at actual address. Example: .l -4 fffffffc: ******** * 00000000: 00000000 cmove #$0000,$dff000 00000004: 00c00276 cmove #$0276,$dff0c0 00000008: 00fc0818 cmove #$0818,$dff0fc 0000000c: 00fc081a cmove #$081a,$dff0fc 00000010: 00fc081c cmove #$081c,$dff0fc 00000014: 00fc081e cmove #$081e,$dff0fc 00000018: 00fc0820 cmove #$0820,$dff0fc . 3.4.5 Print Text ------------------ Usage: o (s)(e) Displays the desired area area of memory as text, likely to a text editor. There is no address header before each line. Lines longer than 80 chars are truncated. All CTRL chars cause a line feed except TAB which is interpreted as 8-spacing tabulator. Memory that is not defined and hence not readable is represented by asterixes. If the full charset is enabled, it will be used. This command mainly serves to display source codes somewhere in memory. o [s][e] Display text from s to e. o [s] Display 8 lines text from s. o Display 8 lines text at actual address. Example: .o 201000 . . . . . À. v. ü. . 3.4.6 View Plane ------------------ Usage: P (a)(n) Initiates the bitplane viewer. SIM will display memory starting at a given address as bitplane graphic with modulo in hires or lores. Either 240 or 184 lines are used for the graphics in black/white color, depending on PAL/NTSC mode. The bottom two text lines are used as a seperating bar and a status line indicating current start address, modulo and resolution. SIM uses the page memory managing and only displays parts of the addressing space containing memory. Undefined memory is zeroed and hence black. It is possible to look at the full range of memory, also at fast and expansion ram and rom. While the viewer is active, the following keys are used for its control: Terminates the command and continues execution of the current command line. Toggles between hires and lores. Modulo is adjusted so the graphics shrink or expand in width but don't get mixed up. Resets modulo to zero. Increases modulo by 2. Decreases modulo by 2. Increases modulo by 16. Decreases modulo by 16. One line up. Decreases address by line length+modulo. One line down. Increases address by line length+modulo. One word left. Increases address by 2. One word right. Decreases address by 2. One page up. Decreases address by page length. One page down. Increases address by page length. Modulo is limited to a range of $ffda to 3fd8 for lores, $ffb2 to $3db0 for hires display. Therefore line lengths range from 2 to $4000 bytes per line. The resolution used at termination will be used again when the comand is used next time. P [a][n] View bitplane at a with modulo n. P [a] View bitplane at a with same modulo. P View bitplane at actual address. Example: .P fc0000 28 . 3.4.7 Hear Memory ------------------- Usage: H [s][e](n) Sends memory as sample to audio chanel 0 with a given period. Volume is maximum by default. When no period is given for the first time, SIM will use 300. Else the last used period will be reused. The period can range from 80 to $7fff. While listening, The address where the sample words are currently taken from (aprox.) is displayed in the footer. The page memory managing is used and only defined memory is heard at. Undefined memory causes silence. By pressing CTRL, the command can be stopped. H [s][e][n] Hear memory from s to e with period n. H [s][e] Hear memory from s to e with same period. Example: .H 0 20000 80 . 3.5 Memory Editition Commands ================================= Memory editition is severely controled. No changes in SIM itself, symbol nodes or the workmem are allowed. An attempt to edit such memory either causes an error or is not done. 3.4.1 Edit Memory ------------------- Usage: e (a)(d) The edit command can be used to change memory directly, allowing different data forms. Data is written using the page memory managing with the exception that only protection of memory is checked and the interrupt vectors and backup are mirrored. The pages themselves are ignored. You can also write to undefined memory. This enables to write to the custom registers which in most cases are not declared as readable. For an overview of data line buildup refere to the appropriate section. If this command is executed without datas, SIM will start a loop where it requests data to write to an address until no data are entered. Therefore it builds the next command line by itself which will look like 'e>xxxxxxx: '. You can leave the loop by pressing without entering a data line. If there is an error in the data line, it is displayed but the entier line is not written to memory. Datas are written as words if possible. This is neccessary to edit the custom registers which are not used by SIM. In the above described mode, SIM will recognize if the next command line already was a line built by the edit loop and only changes the address and leaves the actual data line untouched. e [a][d] Write data d to address a. e [a] Start editing at a. e Start editing at the actual address. Example: .e 100 e>00000100: 0011,?[4],'SIM!' e>0000010a: .e 4 ?'DIE!' . 3.4.2 Assemble ---------------- Usage: n (a)(i) The assemble command can be used to directly assemble one or multiple instructions to an address. Data is written using the page memory managing with the exception that only protection of memory is checked and the interrupt vectors and backup are mirrored. The pages themselves are ignored. You can also assembly to undefined memory. If this command is executed without an instruction, SIM will start a loop where it requests instructions to assemble to an address until no more instructions are entered. Therefore it builds the next command line by itself which will look like 'n>xxxxxxx: '. You can leave the loop by pressing without entering an instruction. In the above described mode, SIM will recognize if the next command line already was a line built by the assemble loop and only changes the address and leaves the instructions untouched. That way you can enter an entier program and adjust the possible branch addresses by editing them, moving the cursor in the first line of the program and pressing until the last line is executed. Multiple instructions can be seperated by a komma. If an instruction is faulty, an error is printed and the entier line is not assembled to memory. n [a][i] Assemble instructions i to address a n [a] Start assembling at a. n Start assembling at the actual address. Example: .n 100 n>00000100: lea $200,a0, lea $300,a1, moveq #$3f,d0 n>0000010a: move.l (a0)+,(a1)+ n>0000010c: dbra d0,$10a n>00000110: rts n>00000112: . 3.4.3 Transfer Memory ----------------------- Usage: T [s][e][t] The transfer command is used to copy around areas of memory. The page memory managing is used. Undefined areas in the destination are not written to, undefined areas in the source are read zero. If protected memory (symbol nodes, etc.) is in the destination area, an error occures. SIM either uses ascending or descending mode to copy, there will be no faults when copying overlaying areas. T [s][e][t] Copy memory from s to e to t Example: .T fc0000 1000000 200000 . 3.4.4 Occupy Memory --------------------- Usage: O [s][e][d] This command is used to occupy an area of memory with a byte pattern. The page memory managing is used. Undefined areas in the destination are not written to. If protected memory (symbol nodes, etc.) is in the destination area, an error occures. O [s][e][d] Occupy memory from s to e with d. Example: .O 0 80000 'KILL' . ******************************************************************************* 4. Debugger Window ******************************************************************************* ******************************************************************************* 5. Assembler and Calculator ******************************************************************************* 5.1 Assembler Usage ======================= SIM has a full 680x0/688xx assembler builtin which allows you to make changes to programs while debugging. It supports the standard optimisations and aliases used by most other assemblers: - ADDI and ADDA can be replaced by ADD. ADDX can also be replaced by ADD if the effective addresses are address register indirect with predecrement. - SUBI and SUBA can be replaced by SUB. SUBX can also be replaced by SUB if the effective addresses are address register indirect with predecrement. - CMP can be used instead of CMPA, CMPI and CMPM. - EOR, OR and AND can be used instead of EORI, ORI and ANDI. - Bcc and DBcc instructions and PC-relative effective addresses use absolute addresses. It is possible to specify the offset directly by puting a '+' or '-' sign in front (but note that the offset is counted from start of instruction plus 2): 00060010: bra $60000 or 00060010: bra -$12 - If no size is given, Bcc will be optimised to short if possible. - If no size given, memory direct effective addresses are optimised to WORD if possible. - If no size given for an instruction, the default size is used which in most cases is WORD. The assembler will either assemble only instructions which can be executed by the current CPU and coprocessors or all instructions, depending on whether or not the full instruction set is enabled for disassembling/assembling. 5.2 Calculator Usage ======================== The calculator is one of the central functions of SIM, all numeric input is handled by it. It disposes of mostly all operations and value forms. The following operators are supported, sorted by priority when evaluating the term: () Brackets: Correspond to normal brackets. Number of opening and closing brackets must be the same. [] Memory indirection: The result of the term in these brackets an address and the content of the memory at that address will be read. A size directly after the closing bracket will define if the value will be read as a BYTE, WORD or LONG and extended to LONG. I.e.: [4].l reads out AbsExecBase, [$dff002].w reads out the actual DMACON as a WORD. - Prefix change: Changes a positive value to a negative and vice versa. I.e.: -5 is -5, -0 is 0, --6 is 6. ~ Logical NOT: Inverts all 32 bits of the value. I.e.: ~5 is -6. .s Sizing: Any value will be extended to LONG from the size specified. I.e.: $89.b is $ffffff89. The size of the result is used both for the assembler when using memory direct effective addresses and for data input for the memory edit command etc. If multiple sizing operations occure, the last sizing operation in the lowest bracket level defines the finial size of the result. *,/ Multiply and divide: Signed LONG multiplication and division. I.e.: -$56*5 is fffffe52, 9/-3 is -3. \ Modulo: Signed LONG modulo. I.e.: 11\4 is 3. +,- Addition and subtraction: LONG addition and subtraction. I.e.: 1000-9 is 991. << Shift left: Correspond to a multiplication with 2 to the nth power, whereas n is the numer of bits to be shifted. I.e.: $20<<8 is $2000. >> Shift right: Corresponds to a division by 2 to the nth power, whereas n is the numer of bits to be shifted. I.e.: $2000>>8 is $20. & Logical AND: LONG AND operation. I.e.: $1234&$ff00 is $1200. ! Logical EOR: LONG EOR operation. I.e.: $c1!$54 is $a5. | Logical OR: LONG OR operation. I.e.: $1200|$34 is $1234. <> Not equal: Result of this operation is -1 if values not equal, else 0. I.e.: 5<>6 is -1, 3<>3 is 0. = Equal: Result of this operation is -1 if values are equal, else 0. I.e.: 5=6 is 0, 3=3 is -1. <=,=< Lower or same: Signed comparison, result is -1 if value left of operator is lower or the same than the right value. I.e.: 1<=1 is -1, 6<=5 is 0. =>,>= Greater or equal: Signed comparison, result is -1 if value left of operator is greater or equal than the right value. I.e.: 2=>1 is -1, 0=>5 is 0. < Less: Signed comparison, result is -1 if value left of operator is less than the right value. I.e.: 1<1 is 0, 0<5 is -1. > Greater: Signed comparison, result is -1 if value left of operator is greater than the right value. I.e.: 2>1 is -1, 0>5 is 0. As for the form of values, the following are supported: $x Hexadecimal number: A number in hexadecimal form, consisting of max. 8 digits 0-9 and a-f. I.e.: $badcode1 #x Decimal number: A number in decimal form, consisting of digits 0-9. I.e.: #1992. %x Binary number: A number in binary form, consisting of max. 32 digits 0 and 1. I.e.: %1010001011. '," ASCII chars: A number consisting of max. 4 ASCII chars. The string must be introduced and ended with the same sign. If a ' must appear in a string introduced with ', two ' following each other mark one '. The same is valid for the ". I.e.: "SIM!", 'DATA', 'it''s','''' , '"MC"'. ! Last result: Stands for the result of the last term calculated. I.e.: To display 16 bytes at $50000 one can enter the command 'm $50000 !+$10'. @ Actual address. Stands for the actual address used by dump commands and edit/assembly commands. I.e.: @-100. SIM SIM start: The program and base address of SIM. D0-D7 ,A0-A7 ,PC ,SP ,SSP ,USP ,SR ,CCR, ISP, MSP, CAAR, CACR, VBR, SFC, DFC, TT0, AC0, ITT0, IACR0, TT1, AC1, ITT1, IACR1, DTT0, DACR0, DTT1, DACR1, MMUSR, ACUSR, PSR, PCSR, DRPH, DRPL, URP, CRPH, CRPL, SRPH, SRPL, SRP, TC, AC, CAL, VAL, SCC, BAC0-BAC7, BAD0-BAD7, FPCR, FPSR ,FPIAR, SEA, TEA, SX, TX, SIM and M0-M7 CPU/FPU/MMU registers: The calculator can directly use the content of these registers. SSP is the supervisor stack pointer, USP the userstack pointer SP and A7 the actual stack pointer. M0-M7 are variables, M0-M3 are used as view start registers. Because the calculator can only handle operands within long- word bounds, it can only access either the first or second longword of the quadword sized SRP, CRP and DRP. Use CRPH, SRPH and DRPH for the high longword, CRPL, SRPL and DRPL for the low longword of the respective registers. The registers FP0-FP7 cannot be accessed from the calculator. The registers support a special feature which allows to use the registers of a history entry. Add an underscore and the number of the history entry as a decimal number after the register name. I.e.: pc+10-d0, srph_4 x',\x' Symbols: Uses the symbol specified after the '\'. Any symbol can be abreviated by placing a "'". Refere to the chapter about symbols in general for detailed information. A calculator term normally ends at a space, a colon, a semicolon, a komma or a carriage return. If you have opened a bracket, you can have spaces between operators and values, but ONLY then. Otherwise, the end of the term will not be there where you wanted. The calculator can work in decimal or hexadecimal mode. In decimal mode you do not have to write the '#' before a decimal number, but for hexadecimal numbers, the '$' is neccessary. In hexadecimal mode you do not have to write the '$' before a hexadecimal number, but for decimal numbers, the '#' is neccessary. Hexadecimal mode is usually used to get addresses and hexadecimal numbers. For the other cases decimal mode is used, also for the assembler. 5.3 Data Lines ================== 5.4 Disassembly Search Pattern ================================== ******************************************************************************* 6. Safety Features ******************************************************************************* This version of SIM is much safer to use and smarter in detecting abnormal, critical and fatal situations and errors than any previous version has been. There are various built in safety features and a reliable warning system which relieves the user from most basic checks. 6.1 Startup Checks ====================== When SIM is invoked, it does various checks on itself and on the configuration. Most of these checks result in warnings, described in the next chapter. Three of them in fact have other, direct results if they fail. First SIM will test if SIM itself, the display, the backup for the display, the work memory and the nodes of the external symbol list overlay somewhere. Overlays are of course not allowed, i.e. having the display address pointing somewhere in SIM would be fatal. Then it tests if the display is within graphic memory. Additionally it tests if any given backup for the display is entierly within a memory page. If any of these tests fail, SIM will not start up any further. It will disable any display and set the background color to red and wait for you to press the left mouse button. After you confirm this, SIM exits again. Next it does a checksum over its main code. If it changed, SIM will start up, but the text color will be set to red. If damage to SIM was little, you can still use it, hoping that no accesses to any destroyed code or data is made. Better would be to leave SIM and load a fresh copy. 6.1 Warnings ================ SIM disposes of a warning system for various critical happenings. If a new warning is displayed, the screen color turns orange and a text is printed in the header. When you have read the warning text, press to confirm. In the top right corner, a flag field indicates what warnings occured in the current call to SIM. If there are any, make sure that you dealt with the problem before you leave SIM. 6.2 Selfprotection ====================== While SIM is active it prohibits write accesses to memory associated with SIM. You cannot write to SIM itself, to any external symbol nodes or to SIMs work memory. If no backup for the display is used, writing to the display memory is also forbidden. Attempting to do so results in a 'protected memory' error. The only space in SIM you can write to is the SIM base, bytes 72-127. Write attempts to any custom or CIA registers used by SIM while operating are redirected to the corresponding backup or reentry entry in the SIM base. 6.3 The External Interrupt Handler ====================================== While SIM is working, the only interrupts allowed are vertical blanking and CIA-A interrupts (and audio 0 while the 'H' command is executing). All other interrupts are disabled. The Amigas hardware allows external devices like harddisk controlers or other hardware to generate interrupts. Depending on the implementation of the hardware, it does not always suffice to acknowledge an interrupt generated by such an external device by clearing a bit in the INTREQ register. The interrupt server for that device may need to access hardware registers of the device itself to do this, at addresses only it knows about. Therefore SIM can't acknowledge to such an interrupt and would hang. To prevent this, SIM catches any Level 2 and Level 3 interrupts that aren't caused due to a keyboard event or a vertical blank. It will then automatically exit, perform the interrupt handler and enter through the JSR entrance afterwards. ******************************************************************************* 7. Advanced Features ******************************************************************************* 7.1 When not to Call SIM... =============================== There are certain situations in which invoking SIM will cause damage or loss of data. These situations however are very, very special. You will possibly never get to call SIM in one of those. For completion and for the few users who will have to deal with this, here is a list of when SIM shall not be invoked: 1. Never call SIM in the interrupt level 2 before the interrupt routine has read out the ICR register to know about what caused the interrupt. If you do so, SIM will read out the ICR instead of the interrupt. If the value is nonzero, SIM displays a warning. It is your business then to pass the ICR value read by SIM to the interrupt handler. 2. Never call SIM in the keyboard interrupt before it has sent the handshake to the keyboard hardware. If you do so, the keyboard will loose synchronisation and miss one or more keystrokes which can remotely lead to software failures. 3. Never call SIM while doing serial data transfer. If you do so, SIM will display a warning and the transfer is interrupted. 4. Never call SIM in a disk IO routine which uses the DISKBYT register instead of DMA. Doing so will either destroy the data on the disk or the data read from it. ******************************************************************************* 8. Appendixes ******************************************************************************* 8.1 Bibliography ==================== 8.2 Acknowledgements ======================== 8.3 Registered Users ======================== 8.4 Contacting Me... ======================== If you want to register or if you have bugreports, question, ideas, flames or complaints (constructive criticism is always welcome), or if you just want to contact me, write or send a letter to: Stefan Walter Finsterruetistr. 57 8135 Langnau a./A. SWITZERLAND Because snail mail is slow, you can also contact me by phone or by sending a message to the electronic mail address below (If you call by phone, please concider any possible time differences and don't wake me up in the night :). Phone: Switzerland/(0)1/713-01-46 Internet: swalter@avalon.unizh.ch or swalter@amiga.icu.net.ch ------------------------------------------------------------------------------- Stefan Walter, 14.Dec.1993