AttoChess, a complete, playable chess program for 16-bit x86 DOS in 278 bytes

### The board draws itself: no render buffer, no int 21h/09h This accounts for the largest saving. The original renders the position into a separate buffer: it walks the board, transforms each square into a printable character, stores it, appends a $ terminator, and prints the whole string with DO

The board draws itself: no render buffer, no int 21h/09h

This accounts for the largest saving.

The original renders the position into a separate buffer: it walks the board, transforms each square into a printable character, stores it, appends a $ terminator, and prints the whole string with DOS function 09h (int 21h). That path costs a buffer pointer setup, the copy loop's store, the terminator write, and, because the buffer lives after the board, a reserved board array in the image.

AttoChess deletes all of it. The board's border columns are laid out as CR, LF, CR, LF (0Dh, 0Ah, 0Dh, 0Ah) instead of the previous 08h filler. Both CR and LF still have bit 3 set, so every existing border/color mask test fires exactly as before, but now the raw board bytes are already a printable frame. The display loop streams each byte straight to the console with int 29h (DOS fast console output): borders become newlines, empty squares become NULs, and only real pieces take the ASCII transform.

Removed in one move: the render buffer, its pointer setup, the $ terminator, the int 21h/09h string print, and the reserved board array in the file image.