Giant.Metal.Robot: 2017

Wednesday 6 December 2017

csirac "emulator"

I am dabbling with a CSIRAC "emulator", very basic so far. There is a Windows 98 program but it is a little wonky under Wine, so this. Using Frank Hirst's Principles and Operations... and the programming manual (also in the emulator zip) as guide. Not sure about the tape mechanism, but I guess a file to load the programs at least.

/* csirac rustic "emulator" with hello world program
 * 
 * not all src and dest codes decoded yet, and no tape functions
 *  
 */
#include -stdio.h- //these dashes should be lt and gt but blogger won't show them
//#define DEBUG 
int A,B,C,D[15],Src,Dest,S=0,K=0,M , Value ,Reg1=0,Reg2=45 ;

int Store[1024] ={
//0123456789SSSSSDDDDD
0b00000010010000000010, //0  M 13  T  H
0b00000000000000000100, //1  A= M 0
0b00000010001100000101, //2  A = A + PE  
0b00000000000010000000, //3  M 0 = A
0b00000010000000000110, //4  A - M 8 (stop value)
0b00000000000101011001, //5  SKIP IF 0 src=10 (ZA) dest=25 (CS)
0b00000000001010010111, //6  JMP 0 src=20 (Z) dest = 23 (S)
0b00000010111111111111, //7  HALT
0b00000101010000000010, //8  P20-P11 = 21 (stop value)
0x48, 0x45, 0x4C, 0x4C, 0x4F, 0x20, 0x57, 0x4F, 0x52, 0x4C, 0x44, 0x0d,  //9
0b00000000000000000000, //21 spare 
0b00000000000000000000, //22 spare 
0b00000000000000000000, //23 spare 
0b00000000000000000000, //24 spare 
};
int main (void) {
while (S  < 1024){  
  Dest=0b11111 & Store[S];
   if (Dest > 1024) break ;  
  Src=0b11111 & ( Store[S] >> 5 );
   if (Src > 1024 ) break ;
   K=Store[S] >>10;

  if (Src==0) Value = Store[K] ; 
  //if (Src==1) Value =  ; 
  if (Src==2) Value = Reg1 ; 
  if (Src==3) Value = Reg2 ; 
  if (Src==4) Value = A;
  if (Src==5 ) Value =  A >> 20 ; 
  if (Src==6 ) Value = A /2  ; 
  if (Src==7 ) Value =  A*2; 
  if (Src==8 ) Value = 0b00001111 & A  ; 
  if (Src==9 ) { Value =  A ; A = 0 ; } 
  if (Src==10 ) { if (A == 0) Value = 0 ; else Value = 1 ; }
  if (Src==11 ) Value = B ; 
  if (Src==12 ) { if ((B >> 20) == 1 ) Value = 99; else Value =0 ; } ; 
  if (Src==13 ) Value = B >> 1 ; 
  if (Src==14 ) Value = C ; 
  if (Src==15 ) Value = C >> 20  ; 
  if (Src==20) Value =0;
  if (Src==23) Value =S;
  if (Src==24) Value=0b00000000010000000000; 
  if (Src==25) Value=0b00000000000000000001; 
  if (Src==26) Value = K;

  if (Dest==0) Store[K]=Value;
  if (Dest==2) { printf ("%c", Value);
   #ifdef DEBUG
     printf("\n");
  #endif
 }
  if (Dest==4) A = Value; 
  if (Dest==5) A = A + Value;
  if (Dest==6) A = A - Value;
  if (Dest==7) A = A & Value;
  if (Dest==8) A = A | Value;
  if (Dest==9) A = A ^ Value;
  if (Dest==16) C = C - Value;
  
  if (Dest==23) { S = Value - 1 ; if (S > 1024 ) break;}
  if (Dest==25) if (Value==0) S++;
  if (Dest==26) K = Value;
  if ((Src == 31) && (Dest==31)) {  printf("\n\n*Halt*\n\n");break; }

  S++;
  
  #ifdef DEBUG 
   printf("A=%d Src=%d Dest=%d K=%d S=%d Store[%d]=%d\n",A,Src,Dest,K,S,S,Store[S] );
  #endif 
}
 printf ("\n");
  #ifdef DEBUG 
   // display memory store
   for (S=0;S <=20 ;S++) { printf("%d = %d\n",S,Store[S]); }
  #endif
 return 0;
}