EE 2504: Introduction to Computer Engineering

MANOSIM and MANOASM User's Guide

Version 2.20

by

Roger Chen and Dong S. Ha

Bradley Department of Electrical Engineering 
Virginia Polytechnic Institute and State University 
Blacksburg, Virginia 24061-0111

January 1, 1990 
(User's Guide Revised August 20, 1996)

(Revised for Univ. at Albany March 21, 2001)

Table of Contents

Introduction

MANOSIM is a simulator program designed to simulate all the functions of the computer in Chapters 5 and 6 of Computer System Architecture by M. Morris Mano. The simulator is written in "C" and is currently available for IBM based machines. MANOSIM can simulate all functions of the "Mano Machine" including input-output functions and interrupts. The simulator is completely interactive and is designed to be used by persons with little experience in using computers.

MANOASM is an assembler program that will input programs written in the assembly language for the Mano Basic Machine, which is described in Chapter 6 of Computer System Architecture by M. Morris Mano.  It will output a file that can be input to MANOSIM.  Instructions for MANOASM are given  below .  You can use MANOSIM and MANOASM independently of one another.

The names of the executables supplied here mano2 and manoasm differ from the names MANOSIM and MANOASM documented below.  Please make the appropriate substitutions.  Please report variations from the behavior documented below to  sdc@cs.albany.edu  so I can improve this page.

The concepts for the software package and this manual are derived from the original MANOSIM written by J. Pelissier, August 1983.

Starting MANOSIM

To use the software, you must first obtain your own copies of MANOASM and/or  MANOSIM.  They are available as (uncompressed) MSDOS executables:
  1. Download the files  manoasm.exe  and  mano2.exe and save them in the directory where you will use the assembler and simulator.
Your instructor may announce other ways to obtain MANOSIM. Once you have manosim.exe, you are ready to run the program. Simply execute MANOSIM at the DOS prompt. You will see the following start-up message. MANOSIM is now ready to accept your commands. All commands may be typed in upper or lower case letters.

MANOSIM Commands

All interaction between MANOSIM and the user is accomplished through a set of commands. Each command consists of a name, such as "TRACE", and may be followed by several parameters.

The parameters consist of keywords, such as "ON" or "OFF", expressions, text, and file names. Numbers in expressions may be entered in either decimal or hex. To enter a number in hex, the number must be preceded by a '$' character.

Expressions can be simple mathematical expressions, and even labels. As an example, the numerical convert command "CV" will accept an expression "expr" that can contain a combination of numbers and labels, and use the arithmetic operators "+" and "-".

Examples:
* CV 5+4+$100 adds decimal 5 and 4 to hex $100
* CV $FF2 converts hex $FF2
* CV START displays value of label START (if present)
* CV START + $20  
* CV (START-END)+1 YES! Parentheses are okay
Evaluation always occurs from right to left, so, for example the following expressions produce different results.
* CV (10-5)+2 Evaluates to 7
* CV 10-5+2 Evaluates to -(5+2)+10, or 3
Types of parameters used for commands are as follows.

"number" A numerical expression (as in above examples)
"addr-val" An expression that refers to a Mano machine memory address and that does not exceed $FFF
"text" Any text strings (quotes are not necessary)
"filename" DOS file name that can include path and extension
ON, OFF, M, PC, AC, E, IEN Specific MANOSIM keywords

MANOSIM Command List

Below is a list of commands that MANOSIM recognizes. Parameters listed in [ ] are optional. Many commands have abbreviated forms.

BREAKPOINT (Abbreviations: "BPT", "B")

Syntax:
BREAKPOINT [number] addr-val
BPT [number] ON
BPT [number] OFF
BPT
The BREAKPOINT command instructs the simulator to stop execution of a program immediately before executing the instruction located at the specified address.

The simulator will always execute at least one instruction. Therefore, if execution begins at a breakpoint, the simulator will ignore the breakpoint for the instruction cycle. Program execution may be continued by entering the "GO" command.

There are a total of six unique breakpoints. "number" specifies which breakpoint, and if omitted, breakpoint 1 is assumed. The "ON" and "OFF" keywords turn a certain breakpoint on and off, respectively.

Examples:
BPT START+5 Sets breakpoint 1 to label START plus 5 words and enables it
BPT 3 $100 Enables and set break 3 to $100
BPT 5 OFF Disables breakpoint 5
BPT Displays all breakpoints and value

COMMENT (Abbreviation: "C")

Syntax:
COMMENT text
The COMMENT command is used for documentation purposes. Any text following "COMMENT" will be ignored by the simulator.

CONVERT (Abbreviation: "CV")

Syntax:
CONVERT number
The CONVERT command will convert a numerical expression (hex or decimal constant or label, or combination of constants and/or labels using math operators "+" and "-") to decimal unsigned, decimal signed two's complement, and hexadecimal form. The value of the expression and any constants must be between $0000 and $FFFF, inclusive, if entered in hex or between -32768 and 65535, inclusive, if entered in decimal.

DISASSEMBLE (Abbreviation: "DIS")

Syntax:
DISASSEMBLE addr-val1 [addr-val2]
The DISASSEMBLE command causes the section of memory between addr-val1 and addr-val2, inclusive, to be disassembled. The disassembled listing will include the address, contents, and mnemonic. The address of the operand and the indirect indicator will also be printed, if applicable. Labels from source code are not included in the disassembly.

Illegal opcodes will produce "???" as the mnemonic.

The disassembler has no way of distinguishing areas of memory containing programs from those containing data or garbage. Consequently, the disassembler will attempt to disassemble any section of memory that it is told to do so. If a program is not present at that section of memory, the disassembler will produce meaningless results.

Pressing the escape (ESC) key while MANOSIM is disassembling will halt the disassembly and MANOSIM will prompt you for a new command. Pressing the SPACE key during a disassembly will pause and un-pause the listing.

DISPLAY (Abbreviation: "D")

Syntax:
DISPLAY addr-val1 [addr-val2]
This command will cause the section of memory between addr-val1 and addr-val2 to be displayed. Data is displayed in hexadecimal form.

ERASE

Syntax:
ERASE filename
The ERASE command will cause a file to be removed from the floppy disk. Care should be taken to ensure that a file is not erased by mistake. Once a file is erased, it requires a special software utility to get it back.

The full file name must be specified as if you were using the DOS "DEL" command. An error is displayed if the file does not exist.

FILES

Syntax:
FILES filename
The FILES command causes the file names contained on the floppy disk to be displayed. Because of the way DOS handles a FILES request, the file names will not appear in the log output. "filename" must be a DOS file specification. It may contain wildcards "*" or "?".

GO (Abbreviation: "G")

Syntax:
GO [addr-val1] [addr-val2]
This command instructs the simulator to begin executing a program in memory. Entering "GO" without parameters starts at the address currently stored in the program counter. If [addr-val1] is specified, the program counter is set to [addr-val1] and then execution is begun. Specifying a second address will set an unused breakpoint to [addr-val2] and enable that breakpoint. If all breakpoints are in use, it will re-assign breakpoint 1 to [addr-val2]. The computer will execute commands between [addr-val1] and [addr-val2], considering the program will reach [addr-val2]. While the computer is executing a program, all input/output interaction will be through the computer screen and keyboard, as if it were acting as a terminal to the host computer. Input to the "host" is buffered until read by "INP" instructions. Output from "OUT" occurs immediately.

INITIALIZE (Abbreviation: "INI")

Syntax:
INITIALIZE
If you use the "HXC" assembly language directive instead of "HEX" and the "DCC" directive instead of "DEC", you can automatically initialize those memory locations in MANOSIM using the INITIALIZE command. INITIALIZE resets the memory values defined by "HXC" or "DCC" to their original (assembled) values. This is useful if the program modifies values (e.g. counters or pointers) stored in memory during execution that need to be reset to run the program again.

IOCYC (Abbreviation: "IOC")

Syntax:
IOCYC number
The IOCYC command allows the user to specify how many instruction cycles are required to complete each input or output request of the Mano Machine. See MANOSIM Input-Output section for a detailed explanation.

LOAD (Abbreviation: "L")

Syntax:
LOAD filename[.OBJ]
The LOAD command reads the contents of an object file into memory. The name of the object file is specified in "filename".

LOG

Syntax:
LOG ON filename
LOG OFF
The "LOG ON" command creates a log file. This will cause all information displayed on the screen to be placed in the log file specified by "filename". Note that no file extension is implied. If desired, an extension must be included in "filename". After ending the simulator session, this file may be printed or used with another application. If the specified file already exists, all new information will be appended at the end of the file. This allows the user to include only particular parts of the MANOSIM session in the log file.

"LOG OFF" instructs the simulator to stop echoing information to the log file.

Note that when the log command is on, the disk will occasionally start and stop. This is normal.

QUIT

Syntax:
QUIT
This command is used to exit the simulator. Memory contents and all changes will be lost unless the SAVE command has been used.

RESET

Syntax:
RESET
This command resets all the simulator options to their default values. These are summarized in the following table. The log option and memory contents are not affected by this command.
Parameter Default Value
IEN 0
Accumulator 0
STEPS infinite
Breakpoints clear
Input Buffer clear
E 0
Program Counter 0
TRACE OFF
IOCYC 5

SAVE

Syntax:
SAVE addr-val1 addr-val2 filename[.OBJ]
This command creates an object file containing the contents of memory between addr-val1 and addr-val2, inclusive. The name of the object file is specified by "filename".

If the specified file already exists, the old file will be replaced by the new one.

SET (Abbreviation: "S")

Syntax Option 1:
SET PC [constant]
SET AC [constant]
SET E [constant]
SET IEN [constant]
This first version of the command allows the user to examine and optionally change the value of the PC, AC, E or IEN registers. If "constant" is specified, the register will be set to that value. The constant may be in decimal or hex.
Syntax Option 2:
SET M addr-val
This second version of the command allows the user to examine and optionally set individual bytes of memory. Upon receiving the SET command, the simulator will display the address specified by "addr-val" and the contents of memory at that address. If the user simply types the return (ENTER) key, the next sequential memory location will be displayed. If the user enters a number, that value will be set at the current memory location before the next location is displayed. A preceding "$" character is required for hex values.

To exit this command, enter a "/" character.

SOURCE

Syntax:
SOURCE filename[.TXT]
This command reads and assembles a source code file like MANOASM. The only advantage is that labels used in the program will be accessible while using the simulator. In this way, more than one program can be loaded at a time, provided:
  1. they do not occupy the same space in memory, and
  2. they do not use labels with the same name.
Subsequent programs can use the labels from previously loaded programs, thus the concept of program module linking can be achieved.

STEPS (Abbreviation: "ST")

Syntax:
STEPS number
This command specifies the maximum number of instructions the simulator should execute before stopping. This will allow the user some recovery from infinite loops and branches outside the program area.

After execution has stopped, it may be continued again simply by entering the "GO" command.

Setting STEPS to 1 will allow the user to single step through a program. Setting STEPS to 0 will set an infinite number of steps. The default for STEPS is infinity.

TIMESTAMP (Abbreviation: "TS")

Syntax:
TIMESTAMP
This command causes the simulator to display the current time and date (as set on your computer).

TRACE (Abbreviation: "T")

Syntax:
TRACE ON
TRACE OFF
This command causes the simulator to trace the execution of a program. The simulator will display the instruction, operand, and processor status immediately after each instruction is executed. When TRACE is OFF, the simulator will execute a program without printing any information regarding its execution. Note that programs execute considerably faster when the trace option is off.

MANOSIM Input-Output

MANOSIM will very nearly simulate the action of a low-speed data terminal as an input-output (I/O) device. The simulation is described below.

Input

Input characters are sequentially retrieved from the input buffer and placed in the INPR register. When a character is placed in the INPR register, the FGI flag is set. When a character is removed from the INPR register by an INP instruction, the FGI flag is reset (cleared), but the INPR register is unaffected. Once an INP instruction is executed, the simulator waits the number of machine cycles specified by the "IOCYC" command before another character is retrieved from the input buffer and placed in INPR, thus setting the FGI flag. If an attempt is made to execute an INP instruction while the FGI flag is reset, the current contents of INPR will be moved, causing duplication of characters read. This action is consistent with the action of most serial interfaces.

Output

When an OUT instruction is executed, data is moved to the OUTR register and the FGO flag is reset (cleared). This data is then echoed to the simulator display. The simulator will then wait the number of instruction cycles specified by the "IOCYC" command before setting the FGO flag again. If an OUT instruction is executed while the FGO flag is reset, the OUT information will be lost. OUT instructions that occur while TRACE is ON will work concurrently with the trace display, so some lines of the trace will be shifted over one column.

MANOASM Assembler

MANOASM is a two-pass assembler for converting MANO source code (as described in Chapter 6 of Computer Systems Architecture) into object code for use in the MANOSIM simulator. All of the conventions and rules of proper syntax outlined in the book apply here.

Executing MANOASM

To invoke the assembler and assemble a single file, use the following at the DOS prompt: "sourcefile" is the name of the source code file created by a text editor (such as EDLIN in DOS or the Windows Notepad). If the -L option is specified, MANOASM will produce an listing file for the assembled program, including a label chart. If a name is not specified after the -L option, the listing file name will default to the "sourcefile" root and the extension ".LST". The -O option is used only if you want the object file to be named something other than the root of the "sourcefile" with extension ".OBJ".

Example: A> MANOASM PROJ_3 -L

This will assemble the file "PROJ_3.TXT" and produce the object file named "PROJ_3.OBJ" and the list file "PROJ_3.LST".

HXC and DCC Directives

"HXC" and "DCC" are two extra pseudo-ops and act exactly like "HEX" and "DEC", respectively, except that the associated memory location can be reset to its initial value using the INITIALIZE (INI) command in MANOSIM.

MANOASM Error Messages

"Bad opcode spec or unknown opcode"
An opcode unknown to the assembler was given, or a label was specified without a comma.
"Memory overflow"
Program went past the bounds of memory, FFF hex.
"Bad label (too long)"
Label was too long or contained an unrecognizable ASCII character.
"Operand field error (too long)"
Operand specification was too long (math expression too complex), or slash character not encountered before comment(s).
"Numeric overflow"
Math expression produced numerical over or underflow
"Bad operand or missing value"
Operand contains insufficient or unrecognizable information.
"Bad address spec (overflow)"
Address field contains value outside of memory bounds (FFF hex).
"Too many '(' parens"
Not enough close-parentheses were specified in an expression.
"Bad expression, value expected"
A non-numerical or unknown label was encountered in a math expression, or operand field contains misspelled label.
"Bad expression, math operation expected"
A "+" or "-" was expected in a math expression, or an illegal ASCII character was used to specify a label.

MANOSIM Example Run

A> MANOSIM
*.C
* C FIRST WE WILL ENTER THE OP-CODES FROM TABLE 6-14
* C
* SET M $100
:100: (0000) $7400
:101: (0000) $2113
:102: (0000) $7080
:103: (0000) $3113
:104: (0000) $7002
:105: (0000) $4107
:106: (0000) $410B
:107: (0000) $2112
:108: (0000) $1114
:109: (0000) $3114
:10A: (0000) $7400
:10B: (0000) $2112
:10C: (0000) $7004
:10D: (0000) $3112
:10E: (0000) $6111
:10F: (0000) $4100
:110: (0000) $7001
:111: (0000) $FFF8
:112: (0000) $000F
:113: (0000) $000B
:114: (0000) 0
:115: (0000) /
* C
* C NOW, WE WILL CHECK TO SEE IF THE PROGRAM IS THE SAME AS THE BOOK
* C
* DIS $100 $114
100: 7400   CLE
101: 2113   LDA   113
102: 7080   CIR
103: 3113   STA   113
104: 7002   SZE
105: 4107   BUN   107
106: 410B   BUN   10B
107: 2112   LDA   112
108: 1114   ADD   114
109: 3114   STA   114
10A: 7400   CLE
10B: 2112   LDA   112
10C: 7004   SZA
10D: 3112   STA   112
10E: 6111   ISZ   111
10F: 4100   BUN   100
110: 7001   HLT
111: FFF8   ???
112: 000F   AND   00F
113: 000B   AND   00B
114: 0000   AND   000
* C
* C OOPS!   ADDRESS $10C SHOULD HAVE BEEN SOMETHING ELSE!
* C
* S M $10C
:10C: (7004) $7040
:10D: (3112) /
* C
* C WE WILL SAVE THE PROGRAM TO DISK, SO WE DON'T HAVE TO ENTER IN
* C  ALL THOSE CODES AGAIN.
* C
* SAVE $100 $114 MYPROG
* C
* C NOW, WE WILL SET UP THE EMULATOR TO BEGIN AT START OF THE PROGRAM,
* C AND "WATCH" THE FIRST FEW INSTRUCTIONS.
* C
* RESET
*** System Reset ***
* SET PC $100
PC = 100
* TRACE ON
TRACE = ON
* STEPS 10
* C
* C WE WILL ALSO SAVE THE OUTPUT TO A LOG FILE, TO BE PRINTED LATER
* C
* LOG JOURNAL.TXT
* GO


+PC--Cont--Instruction+ +Mem-Ind+  E--AC--I-INPR-O-OUTR-IEN
100: 7400   CLE                    0 0000 0  01  0   01  0
101: 2113   LDA  113    000B       0 000B 0  01  0   01  0
102: 7080   CIR                    1 0005 0  01  0   01  0
103: 3113   STA  113    000B       1 0005 0  01  0   01  0
104: 7002   SZE                    1 0005 0  01  0   01  0
105: 4107   BUN  107    2112       1 0005 0  01  1   01  0
107: 2112   LDA  112    000F       1 000F 0  01  1   01  0
108: 1114   ADD  114    0000       0 000F 0  01  1   01  0
109: 3114   STA  114    0000       0 000F 0  01  1   01  0
10A: 7400   CLE                    0 000F 0  01  1   01  0           


--> Execution stopped after 10 steps, due to reaching STEPS
* C
* C NOTICE THAT THE PROCESSOR STATUS INFORMATION ON THE RIGHT DEPICTS
* C THE STATUS IMMEDIATELY AFTER THE INSTRUCTION IS EXECUTED.
* C
* LOG OFF
* C
* C EVERYTHING LOOKS OKAY, SO WE WILL LET IT RUN UNTIL IT STOPS
* C
* TRACE OFF
TRACE = OFF
* ST 0
* GO
--> Execution 
stopped after 90 steps, due to HLT at 110
* C
* C THE PROCESSOR STOPPED BECAUSE OF THE HLT INSTRUCTION.  THIS IS
* C  NORMAL.  WHAT IS THE RESULT?  WHAT IS IN THE AC REGISTER?
* C
* DISPLAY $100 $120
100: 7400 2113 7080 3113 7002 4107 410B 2112
108: 1114 3114 7400 2112 7040 3112 6111 4100
110: 7001 0000 0F00 0000 00A5 0000 0000 0000
118: 0000 0000 0000 0000 0000 0000 0000 0000
* SET AC
AC = 0F00
* C
* C THE ANSWER IS $00A5, WHICH IS CORRECT.  NOTE THAT IF WE RUN THE PROGRAM
* C  AGAIN, THE PROGRAM WILL NOT WORK PROPERLY BECAUSE THE CONTENTS OF
* C  "CTR", "X", AND "Y" HAVE BEEN MODIFIED.  WE MUST EITHER RE-EDIT THESE
* C  VALUES, OR RE-LOAD THE PROGRAM.  HERE, WE WILL DO BOTH.
* C
* LOAD MYPROG
* SET M $112
:112: (000F) 117
:113: (000B) 82
:114: (0000) /
* C
* C NOTE THAT THESE ARE IN THEIR DECIMAL FORM. WE WILL NOW RUN THE PROGRAM
* C  AGAIN WITH THESE NEW VALUES.
* C
* GO $100
--> Execution stopped after 100 steps, due to HLT at 110
* DISPLAY $114
114: 257A
* C
* C WHAT IS THIS VALUE IN DECIMAL?
* C
* CV $257A DEC = 9594 (9594), HEX = $257A
* C
* C WOW!  IT WORKS!
* C
Comments to: midkiff@vt.edu
Last updated: August 20, 1996
http://fiddle.ee.vt.edu/courses/ee2504/mano_man.html
© 1990, Roger Chen and Dong S. Ha (minor revisions August, 1996 by Scott F. Midkiff)