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HW9.md

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Memory:

// This file is part of www.nand2tetris.org // and the book "The Elements of Computing Systems" // by Nisan and Schocken, MIT Press. // File name: projects/05/Memory.hdl

/**

  • This chip implements the complete address space of the
  • computer's data memory, including RAM and memory mapped I/O.
  • The chip facilitates read and write operations, as follows:
  • Read:  out(t) = Memory[address(t)](t)

  • Write: If load(t-1) then Memory[address(t-1)](t) = in(t-1)
  • In words: the chip always outputs the value stored at the memory
  • location specified by address. If load == 1, the in value is loaded
  • into the memory location specified by address. This value becomes
  • available through the out output in the next time step.
  • Address space rules:
  • Only the upper 16K+8K+1 words of the Memory chip are used.
  • Access to address>0x6000 is invalid. Access to any address in
  • the range 0x4000 to 0x5FFF results in accessing the screen memory
  • map. Access to address 0x6000 results in accessing the keyboard
  • memory map. The behavior in these addresses is described in the
  • Screen and Keyboard chip specifications given in the book. */

CHIP Memory { IN in[16], load, address[15]; OUT out[16];

PARTS:
DMux4Way(in=load, sel=address[13..14], a=loadram1, b=loadram2, c=loadscreen, d=loadkbd);
Or(a=loadram1, b=loadram2, out=loadram);
RAM16K(in=in, load=loadram, address=address[0..13], out=ramout);
Screen(in=in, load=loadscreen, address=address[0..12], out=scrout);
Keyboard(out=kbout);
Mux4Way16(a=ramout, b=ramout, c=scrout, d=kbout, sel=address[13..14], out=out);

} // 0000 000 RAM start // 0011 FFF RAM end // 0100 000 Screen start // 0101 FFF Screen end // 0110 000 Keyboard

Computer:

Memory

// This file is part of www.nand2tetris.org // and the book "The Elements of Computing Systems" // by Nisan and Schocken, MIT Press. // File name: projects/05/Computer.hdl

/**

  • The Computer chip, i.e. the top-most chip of the Hack architecture.
  • The Computer chip consists of CPU, ROM and RAM chip-parts.
  • It is assumed that the ROM is pre-loaded with some Hack program.
  • The Computer chip has a single 1-bit input, named "reset".
  • When reset is 0, the stored program starts executing.
  • When reset is 1, the program's execution restarts.
  • Thus, to start a program’s execution, reset must be pushed "up" (1)
  • and "down" (0). From this point onward the user is at the mercy of
  • the software. In particular, depending on the program loaded into
  • the computer, the screen may show some output and the user may be
  • expected to interact with the computer via the keyboard. */

CHIP Computer {

IN reset;

PARTS:
ROM32K(address=pc, out=instruction);
CPU(inM=memOut, instruction=instruction, reset=reset, outM=outM, 
    writeM=writeM, addressM=addressM, pc=pc);
Memory(in=outM, load=writeM, address=addressM, out=memOut);

}