La macchina didattica VM-2


IN :  Indirizzo 4094:  bit di segno = 0 = carattere fresco in ingresso
                       bit di segno = 1 = carattere vecchio

OUT : Indirizzo 4095:  bit di segno = 0 = carattere fresco  in uscita
                       bit di segno = 1 = carattere vecchio



JPOS : 0000aaaaaaaaaaaa     IF (ACC >= 0) THEN PC <-- aaaaaaaaaaaa
JNEG : 0001aaaaaaaaaaaa     IF (ACC < 0)  THEN        ^^^^^^^^^^^^
JZER : 0010aaaaaaaaaaaa     IF (ACC = 0)  THEN           12 bit
JNZE : 0011aaaaaaaaaaaa     IF (ACC <> 0) THEN
JUMP : 1100aaaaaaaaaaaa     PC <-- aaaaaaaaaaaa
HALT : 11111101xxxxxxxx     halt


LODD : 0100aaaaaaaaaaaa     ACC <-- M[ aaaaaaaaaaaa ]
ADDD : 0101aaaaaaaaaaaa     ACC <-- ACC + M[ aaaaaaaaaaaa ]
ANDD : 0110aaaaaaaaaaaa     ACC <-- ACC  AND  M[ aaaaaaaaaaaa ]
STOD : 0111aaaaaaaaaaaa     M[ aaaaaaaaaaaa ] <-- ACC


LODL : 1000aaaaaaaaaaaa     ACC <-- M[ FP + aaaaaaaaaaaa ]
ADDL : 1001aaaaaaaaaaaa     ACC <-- ACC + M[ FP + aaaaaaaaaaaa ]
ANDL : 1010aaaaaaaaaaaa     ACC <-- ACC  AND  M[ FP + aaaaaaaaaaaa ]
STOL : 1011aaaaaaaaaaaa     M[ FP + aaaaaaaaaaaa ] <-- ACC


LDIX : 1101aaaaaaaaaaaa     ACC <-- M[ ACC + aaaaaaaaaaaa ]

LOC8 : 11110000cccccccc     ACC <-- 00000000cccccccc
LOCH : 11110001cccccccc     ACC <-- cccccccc  e bit inferiori immutati
                                    ^^^^^^^^
                                       8 bit

NEGA : 11111010xxxxxxxx     ACC <-- NOT ACC
SIGN : 11111011xxxxxxxx     ACC <-- (-ACC)
RSHF : 11111110xxxxxxxx     ACC <-- (ACC>>1)
LSHF : 11111111xxxxxxxx     ACC <-- (ACC<<1)

SWAS : 11111000xxxxxxxx     ACC <-- 0000(SP); SP <-- old ACC
SWAF : 11111001xxxxxxxx     ACC <-- 0000(FP); FP <-- old ACC
                                    ^^^^

INSP : 11110010cccccccc     SP <-- SP + 0000cccccccc
DESP : 11110011cccccccc     SP <-- SP - 0000cccccccc
                                        ^^^^

PUSH : 11110100xxxxxxxx     M[SP] <-- ACC         SP <-- (SP - 1)

PSHI : 11110101xxxxxxxx     M[SP] <-- M[ ACC ]    SP <-- (SP - 1)

POP :  11110110xxxxxxxx     SP <-- (SP + 1)       ACC <-- M[ SP ]

POPI : 11110111xxxxxxxx     SP <-- (SP + 1)       M[ ACC ] <-- M[ SP ]


CALL : 1110aaaaaaaaaaaa     M[SP] <-- FP   FP <-- SP       SP <-- (SP - 1)
                            M[SP] <-- PC   SP <-- (SP-1)   PC <-- aaaaaaaaaaaa

RETN : 11111100xxxxxxxx     SP <-- FP      PC <-- M[FP-1]  FP <-- M[FP]