MIXAL

MIXAL is the assembly language of the fictitious MIX computer .

The MIX computer is a hypothetical computer from Donald Knuth's The Art of Computer Programming , which can be programmed using MIXAL. An emulation of this computer can be found on the web links under Dan's MIX Simulator and MIXAL Compiler .

Sample programs

hello world

TERM    EQU    19          console device no. (19 = typewriter)
        ORIG   1000        start address
START   OUT    MSG(TERM)   output data at address MSG
        HLT                halt execution
MSG     ALF    "HELLO"
        ALF    " WORL"
        ALF    "D    "
        END    START       end of program

Formation of the faculty function

Eingabe   CON 10            Variable "Eingabe" wird auf "10" gesetzt
Zaehler   CON 0             Variable "Zaehler" wird auf "0" gesetzt
Produkt   CON 1             Variable "Produkt" wird auf "1" gesetzt
Start                       Start des Programms (Label für den nächsten Befehl)
	  LDA Eingabe       "Load A-Register" Lädt den Inhalt der Variablen in das A-Register
	  STA Zaehler       "Store A-Register" Speichert Inhalt des A-Registers in Variable "Zaehler"
Schleife  LDA Produkt       "Load A-Register" Lädt den Inhalt der Variablen "Produkt" in das A-Register
	  MUL Zaehler       Multipliziert A-Registerinhalt mit Variable "Zaehler". Ergebnis wird in A- und X-Register geschrieben
	  STX Produkt       "Store X-Register" Speichert Inhalt des X-Registers in Variable "Produkt"
	  LDA Zaehler       "Load A-Register" Lädt den Inhalt der Variable "Zaehler" in das A-Register
          DECA 1            "Decrement at 1" Inhalt des A-Registers wird um 1 verringert
	  STA Zaehler       "Store A-Register" Speichert Inhalt des A-Registers in Variable "Zaehler"
	  JAP Schleife      "Jump if A Positive" Wenn A>0, springe zurück nach "Schleife"
	  HLT               "Halt"
	  END Start         Ende des Programmes, welches bei Start beginnt. Das Resultat steht in Variable "Produkt"

description

In order to understand this description, practice in dealing with assembly language is helpful.

Flags

The MIX computer has some processor flags that are used to control the program flow.

E flag

Set if the content of the A register is the same as the content of the address in the CMPA command (CMPA is always executed first).

L flag

Set if the content of the A register is less than the content of the address for the CMPA command (CMPA is always executed first).

G flag

Set if the content of the A register is greater than the content of the address for the CMPA command (CMPA is always executed first).