Name     casette;
PartNo   00;
Date     2026-10-03;
Revision 01;
Designer joppe;
Company  unknown;
Assembly None;
Location unknown;
Device   g22v10;


/* ------------------------------------------------------------
   Constants
   ------------------------------------------------------------ */

ar = 'b'0;
sp = 'b'0;


/* ------------------------------------------------------------
   Pin assignments

   Physical signals IOSEL, RD and WR are active-low.
   Their polarity is expressed in the equations with !.
   ------------------------------------------------------------ */

/* inputs */

PIN 1 = CLK;

PIN 2 = A1;
PIN 3 = A2;

PIN 4 = IOSEL;
PIN 5 = RD;
PIN 6 = A0;

PIN 7 = COMP;
PIN 8 = WR;


/* data bus */

PIN 14 = D0;
PIN 15 = D1;
PIN 16 = D2;
PIN 17 = D3;
PIN 18 = D4;
PIN 19 = D5;
PIN 20 = D6;
PIN 21 = D7;


/* registered output */

PIN 22 = LED;


/* ------------------------------------------------------------
   Read register at offset 0

   Conditions:

       /IOSEL = 0
       /RD    = 0
       /WR    = 1
       A2:A0  = 000

   Result:

       D0     = COMP
       D7..D1 = 0
   ------------------------------------------------------------ */

D0 = COMP;

D1 = 'b'0;
D2 = 'b'0;
D3 = 'b'0;
D4 = 'b'0;
D5 = 'b'0;
D6 = 'b'0;
D7 = 'b'0;


D0.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D1.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D2.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D3.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D4.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D5.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D6.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;

D7.OE =
      !IOSEL
    & !RD
    &  WR
    & !A2
    & !A1
    & !A0;


/* ------------------------------------------------------------
   Writable LED register

   Write conditions:

       /IOSEL = 0
       /RD    = 1
       /WR    = 0
       A2:A0  = 000

   During such a write:

       LED.D = D0

   Otherwise:

       LED.D = LED

   Pin 1 (CLK) clocks the registered macrocell.
   ------------------------------------------------------------ */

LED.D =
      (
          !IOSEL
        &  RD
        & !WR
        & !A2
        & !A1
        & !A0
        &  D0
      )

    #

      (
          (
              IOSEL
            # !RD
            #  WR
            #  A2
            #  A1
            #  A0
          )
        & LED
      );


LED.ar = ar;
LED.sp = sp;