Separate kernel code from test code

Eventually I want the kernel to be loaded from the SD card as well, but
it still needs to separate from user programs.

At some point there should be a folder just for the BIOS, which should
read from the boot block of the SD card and start executing, and thats
it.

sw/kernel/devices/conio.s

@@ -0,0 +1,60 @@
+.importzp sp, sreg
+
+.import _uart_txb_block
+.import _lastchar
+
+.export _cputc
+.export gotoxy
+.export _clrscr
+.export _cgetc
+
+.autoimport	on
+
+.code
+
+; void __fastcall__ cputc (char c);
+_cputc:
+        jsr _uart_txb_block
+        cmp #$0a
+        bne @1
+        lda #$0d
+        jsr _uart_txb_block
+@1:     rts
+
+; void __fastcall__ gotoxy (unsigned char x, unsigned char y);
+gotoxy:
+        phx
+        phy
+        tay                         ; Move y position to y
+        lda (sp)
+        tax                         ; Move x position to x
+        lda #$1b
+        jsr _uart_txb_block
+        lda #'['
+        jsr _uart_txb_block
+        tya
+        jsr _uart_txb_block
+        lda #';'
+        jsr _uart_txb_block
+        txa
+        jsr _uart_txb_block
+        lda #'H'
+        jsr _uart_txb_block
+        ply
+        plx
+        rts
+
+_clrscr:
+        phx
+        lda #$1b
+        jsr _uart_txb_block
+        lda #'c'
+        jsr _uart_txb_block
+        pla
+        rts
+
+_cgetc:
+@2:     lda _lastchar
+        beq @2
+        stz _lastchar
+        rts