Third Chapter

Bit

If load[t]==1 then out[t+1]=in[t] else out[t+1]=out[t]

通過load（t－1）的值決定out（t）是否改變。

CHIP Bit {
    IN in, load;
    OUT out;

    PARTS:
    Mux(a=dffout,b=in,sel=load,out=muxout);
    DFF(in=muxout,out=dffout);
    Or(a=dffout,b=dffout,out=out);
}

Register

CHIP Register {
    IN in[16], load;
    OUT out[16];

    PARTS:
    Bit(in=in[0],load=load,out=out[0]);
    Bit(in=in[1],load=load,out=out[1]);
    Bit(in=in[2],load=load,out=out[2]);
    Bit(in=in[3],load=load,out=out[3]);
    Bit(in=in[4],load=load,out=out[4]);
    Bit(in=in[5],load=load,out=out[5]);
    Bit(in=in[6],load=load,out=out[6]);
    Bit(in=in[7],load=load,out=out[7]);
    Bit(in=in[8],load=load,out=out[8]);
    Bit(in=in[9],load=load,out=out[9]);
    Bit(in=in[10],load=load,out=out[10]);
    Bit(in=in[11],load=load,out=out[11]);
    Bit(in=in[12],load=load,out=out[12]);
    Bit(in=in[13],load=load,out=out[13]);
    Bit(in=in[14],load=load,out=out[14]);
    Bit(in=in[15],load=load,out=out[15]);
}

RAM8

CHIP RAM8 {
    IN in[16], load, address[3];
    OUT out[16];

    PARTS:
    DMux8Way(in=load, sel=address, a=loadA, b=loadB, c=loadC, d=loadD, e=loadE, f=loadF, g=loadG, h=loadH);

    Register(in=in, load=loadA, out=outA);
    Register(in=in, load=loadB, out=outB);
    Register(in=in, load=loadC, out=outC);
    Register(in=in, load=loadD, out=outD);
    Register(in=in, load=loadE, out=outE);
    Register(in=in, load=loadF, out=outF);
    Register(in=in, load=loadG, out=outG);
    Register(in=in, load=loadH, out=outH);

    Mux8Way16(a=outA, b=outB, c=outC, d=outD, e=outE, f=outF, g=outG, h=outH, sel=address, out=out);
}

RAM64

RAM512

RAM4K

RAM16K

PC