33 lines
1.2 KiB
Plaintext
33 lines
1.2 KiB
Plaintext
// This file is part of www.nand2tetris.org
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// and the book "The Elements of Computing Systems"
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// by Nisan and Schocken, MIT Press.
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// File name: tools/builtInChips/Screen.hdl
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/**
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* The Screen (memory map).
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* Same functionality as a 16-bit 8K RAM:
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* If load is asserted, the value of the register selected by
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* address is set to in; Otherwise, the value does not change.
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* The value of the selected register is emitted by out.
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*
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* This built-in implementation has the side effect of continuously
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* refreshing a visual 256 by 512 black-and-white screen, simulated
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* by the simulator. Each row in the visual screen is represented
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* by 32 consecutive 16-bit words, starting at the top left corner
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* of the visual screen. Thus the pixel at row r from the top and
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* column c from the left (0<=r<256, 0<=c<512) reflects the c%16
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* bit (counting from LSB to MSB) of the word found in Screen[r*32+c/16].
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*/
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CHIP Screen {
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IN in[16], // what to write
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load, // write-enable bit
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address[13]; // where to read/write
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OUT out[16]; // Screen value at the given address
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BUILTIN Screen;
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CLOCKED in, load;
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}
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