seperated modules out

10 files changed, 314 insertions, 246 deletions

diff --git a/ROMs/hid.c b/ROMs/hid.c
new file mode 100644
index 0000000..11730e9
--- /dev/null
+++ b/ROMs/hid.c
@@ -0,0 +1,80 @@
+#include "std.c"
+
+#define BUS_HID_SK_START 0x6033
+#define BUS_HID_MS_INDEX 0x602F
+#define BUS_HID_MS_STATE 0x602F + 2
+
+#define SK_MAX 256
+#define SK_NEWLINE 13
+#define SK_BACKSPACE 8
+#define SK_SHIFT 160
+#define SK_A 65
+#define SK_B 66
+#define SK_C 67
+#define SK_D 68
+#define SK_E 69
+#define SK_F 70
+#define SK_G 71
+#define SK_H 72
+#define SK_I 73
+#define SK_J 74
+#define SK_K 75
+#define SK_L 76
+#define SK_M 77
+#define SK_N 78
+#define SK_O 79
+#define SK_P 80
+#define SK_Q 81
+#define SK_R 82
+#define SK_S 83
+#define SK_T 84
+#define SK_U 85
+#define SK_V 86
+#define SK_W 87
+#define SK_X 88
+#define SK_Y 89
+#define SK_Z 90
+
+#define MS_LEFT 1
+#define MS_RIGHT 2
+#define MS_MIDDLE 4
+
+int hid_getKeyState(int scanCode)
+{
+    char* sk_table = BUS_HID_SK_START;
+    int index = scanCode / 8;
+    int bit   = scanCode % 8;
+
+    int val = sk_table[index - 1];
+    return (val & (1 << bit)) != 0;
+}
+
+int hid_getPressedKey()
+{
+    for (int sk = 0; sk < SK_MAX; sk++)
+    {
+        if (hid_getKeyState(sk) && sk != SK_SHIFT)
+            return sk;
+    }
+    return 0;
+}
+
+int hid_waitForPressedKey()
+{
+    while (true)
+    {
+        int sk = hid_getPressedKey();
+        if (sk != 0)
+            return sk;
+    }
+}
+
+int hid_getMouseIndex()
+{
+    return *(BUS_HID_MS_INDEX);
+}
+
+int hid_getMouseState()
+{
+    return *(BUS_HID_MS_STATE);
+}
\ No newline at end of file
diff --git a/ROMs/lib.c b/ROMs/lib.c
deleted file mode 100644
index cd666b9..0000000
--- a/ROMs/lib.c
+++ /dev/null
@@ -1,88 +0,0 @@
-#define SK_MAX 256
-#define SK_NL 13
-#define SK_BS 8
-#define SK_SHIFT 160
-#define SK_A 65
-#define SK_B 66
-#define SK_C 67
-#define SK_D 68
-#define SK_E 69
-
-#define MS_LEFT 1
-#define MS_RIGHT 2
-#define MS_MIDDLE 4
-
-#define SCREEN_WIDTH 128
-#define SCREEN_HEIGHT 64
-#define SCREEN_MAX 128 * 64
-
-#define true 1
-#define false 0
-
-#define COLOR_BLACK 8
-#define COLOR_RED 1
-#define COLOR_GREEN 2
-#define COLOR_BLUE 3
-#define COLOR_TRANSPARENT 0
-
-int setPixel(int x, int y, int c)
-{
-    char* screenStart = 0x402F;
-    int i = (y * SCREEN_WIDTH) + x;
-    screenStart[i] = c;
-}
-
-int setPixel(int i, int c)
-{
-    char* screenStart = 0x402F;
-    screenStart[i] = c;
-}
-
-int clear(int c)
-{
-    char* screenStart = 0x402F;
-    for (int i = 0; i < SCREEN_MAX; i++)
-    {
-        screenStart[i] = c;
-    }
-}
-
-int getKeyState(int scanCode)
-{
-    char* hid = 0x6033;
-    int index = scanCode / 8;
-    int bit   = scanCode % 8;
-
-    int val = hid[index - 1];
-    return (val & (1 << bit)) != 0;
-}
-
-int getPressedKey()
-{
-    for (int sk = 0; sk < SK_MAX; sk++)
-    {
-        if (getKeyState(sk) && sk != SK_SHIFT)
-            return sk;
-    }
-    return 0;
-}
-
-int readKey()
-{
-    while (true)
-    {
-        int sk = getPressedKey();
-        if (sk != 0)
-            return sk;
-    }
-}
-
-int getMouseIndex()
-{
-    return *(0x602F);
-}
-
-int getMouseState()
-{
-    return *(0x602F + 2);
-}
\ No newline at end of file
diff --git a/ROMs/paint.asm b/ROMs/paint.asm
index b4d454f..9a853a4 100644
--- a/ROMs/paint.asm
+++ b/ROMs/paint.asm
@@ -1,96 +1,21 @@
     jmp _main
-_setPixel_int_x__int_y__int_c:; int setPixel(int x, int y, int c)
+_hid_getKeyState_int_scanCode:; int hid_getKeyState(int scanCode)
     pop V0                    ; preserve function return address
-    pop [$71FF]               ; param int x
-    pop [$7201]               ; param int y
-    pop [$7203]               ; param int c
+    pop [$71FF]               ; param int scanCode
     push V0                   ; restore function return address
-    mov $402F, [$7205]        ; int screenStart = $402F
-    push [$7201]              ; left operand
-    mov 128, V1               ; right operand
-    pop V0                    ; get left operand back
-    mul V0, V1                ; compute multiplication
-    push AX                   ; left operand
-    mov [$71FF], V1           ; right operand
-    pop V0                    ; get left operand back
-    add V0, V1                ; compute addition
-    mov AX, [$7207]           ; int i = AX
-    push [$7205]              ; store index obj
-    mov [$7207], V1           ; store indexer
-    pop V0                    ; restore index obj
-    mul V1, 1                 ; multiply indexer by 1
-    add AX, V0                ; add indexer and index obj
-    mov AX, V0                ; move to general purpose register
-    movb [$7203], [V0]        ; [V0] = [$7203]
-    mov 0, V0                 ; fallback return 0
-    ret
-
-_setPixel_int_i__int_c:       ; int setPixel(int i, int c)
-    pop V0                    ; preserve function return address
-    pop [$7209]               ; param int i
-    pop [$720B]               ; param int c
-    push V0                   ; restore function return address
-    mov $402F, [$720D]        ; int screenStart = $402F
-    push [$720D]              ; store index obj
-    mov [$7209], V1           ; store indexer
-    pop V0                    ; restore index obj
-    mul V1, 1                 ; multiply indexer by 1
-    add AX, V0                ; add indexer and index obj
-    mov AX, V0                ; move to general purpose register
-    movb [$720B], [V0]        ; [V0] = [$720B]
-    mov 0, V0                 ; fallback return 0
-    ret
-
-_clear_int_c:                 ; int clear(int c)
-    pop V0                    ; preserve function return address
-    pop [$720F]               ; param int c
-    push V0                   ; restore function return address
-    mov $402F, [$7211]        ; int screenStart = $402F
-    mov 0, [$7213]            ; int i = 0
-_body_1:
-    push [$7213]              ; left operand
-    push 128                  ; left operand
-    mov 64, V1                ; right operand
-    pop V0                    ; get left operand back
-    mul V0, V1                ; compute multiplication
-    mov AX, V1                ; right operand
-    pop V0                    ; get left operand back
-    lt V0, V1                 ; compute less than check
-    not LX
-    bz
-    jmp _end_2                ; if for condition fails, jump to end
-    push [$7211]              ; store index obj
-    mov [$7213], V1           ; store indexer
-    pop V0                    ; restore index obj
-    mul V1, 1                 ; multiply indexer by 1
-    add AX, V0                ; add indexer and index obj
-    mov AX, V0                ; move to general purpose register
-    movb [$720F], [V0]        ; [V0] = [$720F]
-    push [$7213]              ; i++
-    inc [$7213]
-    pop V0
-    jmp _body_1
-_end_2:
-    mov 0, V0                 ; fallback return 0
-    ret
-
-_getKeyState_int_scanCode:    ; int getKeyState(int scanCode)
-    pop V0                    ; preserve function return address
-    pop [$7215]               ; param int scanCode
-    push V0                   ; restore function return address
-    mov $6033, [$7217]        ; int hid = $6033
-    push [$7215]              ; left operand
+    mov $6033, [$7201]        ; int sk_table = $6033
+    push [$71FF]              ; left operand
     mov 8, V1                 ; right operand
     pop V0                    ; get left operand back
     div V0, V1                ; compute division
-    mov AX, [$7219]           ; int index = AX
-    push [$7215]              ; left operand
+    mov AX, [$7203]           ; int index = AX
+    push [$71FF]              ; left operand
     mov 8, V1                 ; right operand
     pop V0                    ; get left operand back
     mod V0, V1                ; compute modulus
-    mov AX, [$721B]           ; int bit = AX
-    push [$7217]              ; store index obj
-    push [$7219]              ; left operand
+    mov AX, [$7205]           ; int bit = AX
+    push [$7201]              ; store index obj
+    push [$7203]              ; left operand
     mov 1, V1                 ; right operand
     pop V0                    ; get left operand back
     sub V0, V1                ; compute subtraction
@@ -99,10 +24,10 @@ _getKeyState_int_scanCode:    ; int getKeyState(int scanCode)
     mul V1, 1                 ; multiply indexer by 1
     add AX, V0                ; add indexer and index obj
     mov AX, V0                ; move to general purpose register
-    mov [V0], [$721D]         ; int val = [V0]
-    push [$721D]              ; left operand
+    mov [V0], [$7207]         ; int val = [V0]
+    push [$7207]              ; left operand
     push 1                    ; left operand
-    mov [$721B], V1           ; right operand
+    mov [$7205], V1           ; right operand
     pop V0                    ; get left operand back
     shl V0, V1                ; compute left shift
     mov DX, V1                ; right operand
@@ -118,26 +43,26 @@ _getKeyState_int_scanCode:    ; int getKeyState(int scanCode)
     mov 0, V0                 ; fallback return 0
     ret
 
-_getPressedKey:               ; int getPressedKey()
-    mov 0, [$721F]            ; int sk = 0
-_body_3:
-    push [$721F]              ; left operand
+_hid_getPressedKey:           ; int hid_getPressedKey()
+    mov 0, [$7209]            ; int sk = 0
+_body_1:
+    push [$7209]              ; left operand
     mov 256, V1               ; right operand
     pop V0                    ; get left operand back
     lt V0, V1                 ; compute less than check
     not LX
     bz
-    jmp _end_4                ; if for condition fails, jump to end
-    push [$721F]              ; arg int scanCode
-    call _getKeyState_int_scanCode; int getKeyState(int scanCode)
+    jmp _end_2                ; if for condition fails, jump to end
+    push [$7209]              ; arg int scanCode
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
     cmp V0, 0                 ; logical and
     not
     bz
-    jmp _clause_5
+    jmp _clause_3
     mov 0, V0                 ; first operand failed, store 0 and skip second
-    jmp _end_6
-_clause_5:
-    push [$721F]              ; left operand
+    jmp _end_4
+_clause_3:
+    push [$7209]              ; left operand
     mov 160, V1               ; right operand
     pop V0                    ; get left operand back
     cmp V0, V1                ; compute inequality check
@@ -145,54 +70,54 @@ _clause_5:
     cmp LX, 0                 ; compare result from second operand to 0
     not
     mov LX, V0                ; store second operand result
-_end_6:
+_end_4:
     not V0
     bz                        ; check if condition
-    jmp _end_7                ; if succeeds, continue, else jump to end
-    mov [$721F], V0           ; return value
+    jmp _end_5                ; if succeeds, continue, else jump to end
+    mov [$7209], V0           ; return value
     ret
-_end_7:
-    push [$721F]              ; i++
-    inc [$721F]
+_end_5:
+    push [$7209]              ; i++
+    inc [$7209]
     pop V0
-    jmp _body_3
-_end_4:
+    jmp _body_1
+_end_2:
     mov 0, V0                 ; return value
     ret
     mov 0, V0                 ; fallback return 0
     ret
 
-_readKey:                     ; int readKey()
-_body_8:
+_hid_waitForPressedKey:       ; int hid_waitForPressedKey()
+_body_6:
     not 1
     bz
-    jmp _end_9                ; if while condition fails, jump to end
-    call _getPressedKey       ; int getPressedKey()
-    mov V0, [$7221]           ; int sk = V0
-    push [$7221]              ; left operand
+    jmp _end_7                ; if while condition fails, jump to end
+    call _hid_getPressedKey   ; int hid_getPressedKey()
+    mov V0, [$720B]           ; int sk = V0
+    push [$720B]              ; left operand
     mov 0, V1                 ; right operand
     pop V0                    ; get left operand back
     cmp V0, V1                ; compute inequality check
     not
     not LX
     bz                        ; check if condition
-    jmp _end_10               ; if succeeds, continue, else jump to end
-    mov [$7221], V0           ; return value
+    jmp _end_8                ; if succeeds, continue, else jump to end
+    mov [$720B], V0           ; return value
     ret
-_end_10:
-    jmp _body_8
-_end_9:
+_end_8:
+    jmp _body_6
+_end_7:
     mov 0, V0                 ; fallback return 0
     ret
 
-_getMouseIndex:               ; int getMouseIndex()
+_hid_getMouseIndex:           ; int hid_getMouseIndex()
     mov $602F, V0             ; move pointer into register for dereference
     mov [V0], V0              ; return value
     ret
     mov 0, V0                 ; fallback return 0
     ret
 
-_getMouseState:               ; int getMouseState()
+_hid_getMouseState:           ; int hid_getMouseState()
     push $602F                ; left operand
     mov 2, V1                 ; right operand
     pop V0                    ; get left operand back
@@ -203,15 +128,90 @@ _getMouseState:               ; int getMouseState()
     mov 0, V0                 ; fallback return 0
     ret
 
+_screen_setPixel_int_x__int_y__int_c:; int screen_setPixel(int x, int y, int c)
+    pop V0                    ; preserve function return address
+    pop [$720D]               ; param int x
+    pop [$720F]               ; param int y
+    pop [$7211]               ; param int c
+    push V0                   ; restore function return address
+    mov $402F, [$7213]        ; int screenStart = $402F
+    push [$720F]              ; left operand
+    mov 128, V1               ; right operand
+    pop V0                    ; get left operand back
+    mul V0, V1                ; compute multiplication
+    push AX                   ; left operand
+    mov [$720D], V1           ; right operand
+    pop V0                    ; get left operand back
+    add V0, V1                ; compute addition
+    mov AX, [$7215]           ; int i = AX
+    push [$7213]              ; store index obj
+    mov [$7215], V1           ; store indexer
+    pop V0                    ; restore index obj
+    mul V1, 1                 ; multiply indexer by 1
+    add AX, V0                ; add indexer and index obj
+    mov AX, V0                ; move to general purpose register
+    movb [$7211], [V0]        ; [V0] = [$7211]
+    mov 0, V0                 ; fallback return 0
+    ret
+
+_screen_setPixel_int_i__int_c:; int screen_setPixel(int i, int c)
+    pop V0                    ; preserve function return address
+    pop [$7217]               ; param int i
+    pop [$7219]               ; param int c
+    push V0                   ; restore function return address
+    mov $402F, [$721B]        ; int screenStart = $402F
+    push [$721B]              ; store index obj
+    mov [$7217], V1           ; store indexer
+    pop V0                    ; restore index obj
+    mul V1, 1                 ; multiply indexer by 1
+    add AX, V0                ; add indexer and index obj
+    mov AX, V0                ; move to general purpose register
+    movb [$7219], [V0]        ; [V0] = [$7219]
+    mov 0, V0                 ; fallback return 0
+    ret
+
+_screen_clear_int_c:          ; int screen_clear(int c)
+    pop V0                    ; preserve function return address
+    pop [$721D]               ; param int c
+    push V0                   ; restore function return address
+    mov $402F, [$721F]        ; int screenStart = $402F
+    mov 0, [$7221]            ; int i = 0
+_body_9:
+    push [$7221]              ; left operand
+    push 128                  ; left operand
+    mov 64, V1                ; right operand
+    pop V0                    ; get left operand back
+    mul V0, V1                ; compute multiplication
+    mov AX, V1                ; right operand
+    pop V0                    ; get left operand back
+    lt V0, V1                 ; compute less than check
+    not LX
+    bz
+    jmp _end_10               ; if for condition fails, jump to end
+    push [$721F]              ; store index obj
+    mov [$7221], V1           ; store indexer
+    pop V0                    ; restore index obj
+    mul V1, 1                 ; multiply indexer by 1
+    add AX, V0                ; add indexer and index obj
+    mov AX, V0                ; move to general purpose register
+    movb [$721D], [V0]        ; [V0] = [$721D]
+    push [$7221]              ; i++
+    inc [$7221]
+    pop V0
+    jmp _body_9
+_end_10:
+    mov 0, V0                 ; fallback return 0
+    ret
+
 _main:                        ; int main()
     mov 0, [$7223]            ; int color = 0
 _body_11:
     not 1
     bz
     jmp _end_12               ; if while condition fails, jump to end
-    call _getMouseIndex       ; int getMouseIndex()
+    call _hid_getMouseIndex   ; int hid_getMouseIndex()
     mov V0, [$7225]           ; int mouseIndex = V0
-    call _getMouseState       ; int getMouseState()
+    call _hid_getMouseState   ; int hid_getMouseState()
     mov V0, [$7227]           ; int mouseState = V0
     push [$7227]              ; left operand
     mov 1, V1                 ; right operand
@@ -230,18 +230,18 @@ _body_11:
     add V0, V1                ; compute addition
     push AX                   ; arg int i
     push [$7225]              ; arg int c
-    call _setPixel_int_i__int_c; int setPixel(int i, int c)
+    call _screen_setPixel_int_i__int_c; int screen_setPixel(int i, int c)
 _end_13:
     push 67                   ; arg int scanCode
-    call _getKeyState_int_scanCode; int getKeyState(int scanCode)
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
     not V0
     bz                        ; check if condition
     jmp _end_14               ; if succeeds, continue, else jump to end
     push 8                    ; arg int c
-    call _clear_int_c         ; int clear(int c)
+    call _screen_clear_int_c  ; int screen_clear(int c)
 _end_14:
     push 65                   ; arg int scanCode
-    call _getKeyState_int_scanCode; int getKeyState(int scanCode)
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
     not V0
     bz                        ; check if condition
     jmp _end_15               ; if succeeds, continue, else jump to end
@@ -250,7 +250,7 @@ _end_14:
     pop V0
 _body_16:
     push 65                   ; arg int scanCode
-    call _getKeyState_int_scanCode; int getKeyState(int scanCode)
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
     not V0
     bz
     jmp _end_17               ; if while condition fails, jump to end
diff --git a/ROMs/paint.c b/ROMs/paint.c
index 7e0427b..71c478e 100644
--- a/ROMs/paint.c
+++ b/ROMs/paint.c
@@ -1,23 +1,25 @@
-#include "lib.c"
+#include "std.c"
+#include "hid.c"
+#include "screen.c"
 
 int main()
 {
 	int color = 0;
     while (true)
     {
-      	int mouseIndex = getMouseIndex();
-		int mouseState = getMouseState();
+      	int mouseIndex = hid_getMouseIndex();
+		int mouseState = hid_getMouseState();
 
         if (mouseState & MS_LEFT)
-            setPixel(mouseIndex, (color % 3) + 1);
+            screen_setPixel(mouseIndex, (color % 3) + 1);
 
-        if (getKeyState(SK_C))
-            clear(COLOR_BLACK);
+        if (hid_getKeyState(SK_C))
+            screen_clear(COLOR_BLACK);
 
- 		if (getKeyState(SK_A))
+ 		if (hid_getKeyState(SK_A))
 		{
             color++;
-			while (getKeyState(SK_A)) { }
+			while (hid_getKeyState(SK_A)) { }
 		}
     }
 }
\ No newline at end of file
diff --git a/ROMs/paint.q1 b/ROMs/paint.q1
index 5105eb8..ecf446d 100644
--- a/ROMs/paint.q1
+++ b/ROMs/paint.q1
diff --git a/ROMs/screen.c b/ROMs/screen.c
new file mode 100644
index 0000000..0eff8c7
--- /dev/null
+++ b/ROMs/screen.c
@@ -0,0 +1,48 @@
+#include "std.c"
+
+#define SCREEN_WIDTH 128
+#define SCREEN_HEIGHT 64
+#define SCREEN_MAX 128 * 64
+
+#define COLOR_TRANSPARENT 0
+#define COLOR_RED 1
+#define COLOR_GREEN 2
+#define COLOR_BLUE 3
+#define COLOR_YELLOW 4
+#define COLOR_CYAN 5
+#define COLOR_MAGENTA 6
+#define COLOR_WHITE 7
+#define COLOR_BLACK 8
+#define COLOR_GRAY 9
+#define COLOR_ORANGE 10
+#define COLOR_PURPLE 11
+#define COLOR_BROWN 12
+#define COLOR_LIGHTGRAY 13
+#define COLOR_DARKGRAY 14
+#define COLOR_LIGHTBLUE 15
+#define COLOR_LIGHTGREEN 16
+
+#define BUS_SCREEN_PALETTE_START 0x3FFF
+#define BUS_SCREEN_PIXELS_START 0x402F
+
+int screen_setPixel(int x, int y, int c)
+{
+    char* screenStart = BUS_SCREEN_PIXELS_START;
+    int i = (y * SCREEN_WIDTH) + x;
+    screenStart[i] = c;
+}
+
+int screen_setPixel(int i, int c)
+{
+    char* screenStart = BUS_SCREEN_PIXELS_START;
+    screenStart[i] = c;
+}
+
+int screen_clear(int c)
+{
+    char* screenStart = BUS_SCREEN_PIXELS_START;
+    for (int i = 0; i < SCREEN_MAX; i++)
+    {
+        screenStart[i] = c;
+    }
+}
\ No newline at end of file
diff --git a/ROMs/std.c b/ROMs/std.c
new file mode 100644
index 0000000..aa0b85f
--- /dev/null
+++ b/ROMs/std.c
@@ -0,0 +1,4 @@
+#include "std.c"
+
+#define true 1
+#define false 0
\ No newline at end of file
diff --git a/ROMs/typewriter.asm b/ROMs/typewriter.asm
index 8a9017b..8b8338a 100644
--- a/ROMs/typewriter.asm
+++ b/ROMs/typewriter.asm
@@ -1,6 +1,6 @@
     jmp _main
     .include "font.bin"
-_setPixel_int_x__int_y__int_c:; int setPixel(int x, int y, int c)
+_screen_setPixel_int_x__int_y__int_c:; int screen_setPixel(int x, int y, int c)
     pop V0                    ; preserve function return address
     pop [$71FF]               ; param int x
     pop [$7201]               ; param int y
@@ -26,7 +26,7 @@ _setPixel_int_x__int_y__int_c:; int setPixel(int x, int y, int c)
     mov 0, V0                 ; fallback return 0
     ret
 
-_setPixel_int_i__int_c:       ; int setPixel(int i, int c)
+_screen_setPixel_int_i__int_c:; int screen_setPixel(int i, int c)
     pop V0                    ; preserve function return address
     pop [$7209]               ; param int i
     pop [$720B]               ; param int c
@@ -42,7 +42,7 @@ _setPixel_int_i__int_c:       ; int setPixel(int i, int c)
     mov 0, V0                 ; fallback return 0
     ret
 
-_clear_int_c:                 ; int clear(int c)
+_screen_clear_int_c:          ; int screen_clear(int c)
     pop V0                    ; preserve function return address
     pop [$720F]               ; param int c
     push V0                   ; restore function return address
@@ -75,11 +75,11 @@ _end_2:
     mov 0, V0                 ; fallback return 0
     ret
 
-_getKeyState_int_scanCode:    ; int getKeyState(int scanCode)
+_hid_getKeyState_int_scanCode:; int hid_getKeyState(int scanCode)
     pop V0                    ; preserve function return address
     pop [$7215]               ; param int scanCode
     push V0                   ; restore function return address
-    mov $6033, [$7217]        ; int hid = $6033
+    mov $6033, [$7217]        ; int sk_table = $6033
     push [$7215]              ; left operand
     mov 8, V1                 ; right operand
     pop V0                    ; get left operand back
@@ -119,7 +119,7 @@ _getKeyState_int_scanCode:    ; int getKeyState(int scanCode)
     mov 0, V0                 ; fallback return 0
     ret
 
-_getPressedKey:               ; int getPressedKey()
+_hid_getPressedKey:           ; int hid_getPressedKey()
     mov 0, [$721F]            ; int sk = 0
 _body_3:
     push [$721F]              ; left operand
@@ -130,7 +130,7 @@ _body_3:
     bz
     jmp _end_4                ; if for condition fails, jump to end
     push [$721F]              ; arg int scanCode
-    call _getKeyState_int_scanCode; int getKeyState(int scanCode)
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
     cmp V0, 0                 ; logical and
     not
     bz
@@ -163,12 +163,12 @@ _end_4:
     mov 0, V0                 ; fallback return 0
     ret
 
-_readKey:                     ; int readKey()
+_hid_waitForPressedKey:       ; int hid_waitForPressedKey()
 _body_8:
     not 1
     bz
     jmp _end_9                ; if while condition fails, jump to end
-    call _getPressedKey       ; int getPressedKey()
+    call _hid_getPressedKey   ; int hid_getPressedKey()
     mov V0, [$7221]           ; int sk = V0
     push [$7221]              ; left operand
     mov 0, V1                 ; right operand
@@ -186,14 +186,14 @@ _end_9:
     mov 0, V0                 ; fallback return 0
     ret
 
-_getMouseIndex:               ; int getMouseIndex()
+_hid_getMouseIndex:           ; int hid_getMouseIndex()
     mov $602F, V0             ; move pointer into register for dereference
     mov [V0], V0              ; return value
     ret
     mov 0, V0                 ; fallback return 0
     ret
 
-_getMouseState:               ; int getMouseState()
+_hid_getMouseState:           ; int hid_getMouseState()
     push $602F                ; left operand
     mov 2, V1                 ; right operand
     pop V0                    ; get left operand back
@@ -283,7 +283,7 @@ _end_16:
     pop V0                    ; get left operand back
     add V0, V1                ; compute addition
     push AX                   ; arg int c
-    call _setPixel_int_x__int_y__int_c; int setPixel(int x, int y, int c)
+    call _screen_setPixel_int_x__int_y__int_c; int screen_setPixel(int x, int y, int c)
     push [$7233]              ; i++
     inc [$7233]
     pop V0
@@ -383,13 +383,13 @@ _end_23:
     mov 0, [$7247]            ; [$7247] = 0
     mov 0, [$7249]            ; [$7249] = 0
     push 8                    ; arg int c
-    call _clear_int_c         ; int clear(int c)
+    call _screen_clear_int_c  ; int screen_clear(int c)
 _end_24:
-    call _readKey             ; int readKey()
+    call _hid_waitForPressedKey; int hid_waitForPressedKey()
     mov V0, [$724B]           ; int sk = V0
 _body_25:
     push [$724B]              ; arg int scanCode
-    call _getKeyState_int_scanCode; int getKeyState(int scanCode)
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
     not V0
     bz
     jmp _end_26               ; if while condition fails, jump to end
@@ -442,6 +442,23 @@ _end_29:
     call _drawChar_int_ch__int_x__int_y__int_color; int drawChar(int ch, int x, int y, int color)
     jmp _body_19              ; continue
 _end_28:
+    push 160                  ; arg int scanCode
+    call _hid_getKeyState_int_scanCode; int hid_getKeyState(int scanCode)
+    not V0
+    bz                        ; check if condition
+    jmp _end_30               ; if succeeds, continue, else jump to end
+    push [$724B]              ; left operand
+    push 97                   ; left operand
+    mov 65, V1                ; right operand
+    pop V0                    ; get left operand back
+    sub V0, V1                ; compute subtraction
+    mov AX, V1                ; right operand
+    pop V0                    ; get left operand back
+    add V0, V1                ; compute addition
+    push AX                   ; computation results
+    pop V1                    ; get computation results back
+    mov V1, [$724B]           ; store back into left param
+_end_30:
     push 1                    ; arg int ch
     push [$7249]              ; arg int x
     push [$7247]              ; arg int y
diff --git a/ROMs/typewriter.c b/ROMs/typewriter.c
index a63a77d..278e048 100644
--- a/ROMs/typewriter.c
+++ b/ROMs/typewriter.c
@@ -1,5 +1,7 @@
 #load "font.bin"
-#include "lib.c"
+#include "std.c"
+#include "screen.c"
+#include "hid.c"
 
 int drawChar(int ch, int x, int y, int color)
 {
@@ -14,8 +16,8 @@ int drawChar(int ch, int x, int y, int color)
         for (int xOff = 0; xOff < 8; xOff++)
         {
             int bit = (row >> (7 - xOff)) & 1;
-            int pix = bit ? 8 : color;
-            setPixel(x + xOff, y + yOff, pix);
+            int pix = bit ? COLOR_BLACK : color;
+            screen_setPixel(x + xOff, y + yOff, pix);
         }
     }
 }
@@ -45,20 +47,20 @@ int main()
         {
             x = 0;
             y = 0;
-            clear(8);
+            screen_clear(COLOR_BLACK);
         }
 
-        int sk = readKey();
-        while (getKeyState(sk)) { }
+        int sk = hid_waitForPressedKey();
+        while (hid_getKeyState(sk)) { }
 
-        if (sk == SK_NL)
+        if (sk == SK_NEWLINE)
         {
             y += 8;
             x = 0;
             continue;
         }
 
-        if (sk == SK_BS)
+        if (sk == SK_BACKSPACE)
         {
             x -= 8;
             if (x < 0)
@@ -66,8 +68,11 @@ int main()
             drawChar(' ', x, y, 1);
             continue;
         }
+
+        if (hid_getKeyState(SK_SHIFT))
+            sk += ('a' - 'A');
         
-        drawChar(sk, x, y, 1);
+        drawChar(sk, x, y, COLOR_RED);
         x += 8;
     }
 }
\ No newline at end of file
diff --git a/ROMs/typewriter.q1 b/ROMs/typewriter.q1
index 163bb6f..82d8114 100644
--- a/ROMs/typewriter.q1
+++ b/ROMs/typewriter.q1