Vice's Vexing VKM Part 6: Finishing Up
VICE’s Vexing VKM: Part 6
Finishing Up
Finally, the effort to map my MacBook keyboard to use in the VICE Commodore 64 emulator comes to an end. Last time we got over the final hurdle, finding an effective mapping for the Commodore’s CTRL and “Commodore” (C=) keys.
This time we map the remaining two rows of keys, and look back on what was learned.
The Fifth Row: Getting Easy Now
The fifth row of the mac was planned to be mapped like this:
Which looks overall pretty easy, based on all we’ve learned.
Left SHIFT, and Doing the CharSet Toggle
Mapping the left SHIFT key on the C64 requires yet another SHIFTFLAGS value:
# 0x0002 2 key is left shift on emulated machine
Making the mapping:
Shift_L 1 7 2 # shift (left)
However, the Commodore 64 has a special sequence where pressing the Commodore (C=) and SHIFT keys at the
same time toggles the display between the uppercase/graphics character set and the lowercase/uppercase set. We learned
this to our detriment when we tried to map SHIFTed keys to use the mapped C= key (option on the mac).
We might have worked around that problem for the mapping, but I still want to keep this functionality available.
Luckily, because we are using the mac’s control key for the C64’s C= key, we can create a mapping for
this action. All we need to do is add 32 (another definition available) to the above mapping’s SHIFTFLAGS value,
and then add one more mapping:
Shift_L 1 7 34 # shift (left)
Shift_L 1 7 3073 # control shift = c= shift
Do you see the trick there? The SHIFTFLAGS value for the second mapping combines three flags:
# 0x0001 1 key is combined with shift for this keysym/scancode
# 0x0400 1024 ctrl modifier required on host
# 0x0800 2048 key is combined with cbm for this keysym/scancode
We’re actually forcing both the “cbm” (C=) and SHIFT keys to be active when this mapping fires. We took
the annoying inadvertent behavior that forced us to not directly map the Commodore key earlier and intentionally
used it here to force the character set toggle to happen.
The Letters
The letter keys on the fifth line map just like they did on the third and fourth. Three mappings per key.
z 1 4 32 # Z
z 1 4 3072 # control Z = c= Z
Z 1 4 1 # shift Z
x 2 7 32 # X
x 2 7 3072 # control X = c= X
X 2 7 1 # shift X
c 2 4 32 # C
c 2 4 3072 # control C = c= C
C 2 4 1 # shift C
v 3 7 32 # V
v 3 7 3072 # control V = c= V
V 3 7 1 # shift V
b 3 4 32 # B
b 3 4 3072 # control B = c= B
B 3 4 1 # shift B
n 4 7 32 # N
n 4 7 3072 # control N = c= N
N 4 7 1 # shift N
m 4 4 32 # M
m 4 4 3072 # control M = c= M
M 4 4 1 # shift M
The Symbols
The symbol keys for the fifth row are as simple as it gets (well, not that I understand things):
comma 5 7 0 # ,
less 5 7 8 # <
period 5 4 32 # .
greater 5 4 8 # >
slash 6 7 0 # /
question 6 7 8 # ?
One Last Shift
The last key on the fifth row is the right SHIFT key, which, like the left SHIFT key, has its own SHIFTFLAGS value:
# 0x0004 4 key is right shift on emulated machine (use only this one
And we’ll set up to be able to toggle the character set.
```Shift_R 6 4 36 # shift (right) hift_R 6 4 3073 # control shift = c= shift
## The Last Row: Modifiers and Actions (and Space)
The sixth row of the mac keyboard is mostly modifiers, a big ol’ space bar, and the cursor keys.
<span class="eimg">
</span>
Of course, this was the *planned* mapping. We now know that the CTRL and C= keys needed to be swapped, and that the left command key has been mapped to act as a “standalone” Commodore (C=) key, just in case.
## The Modifiers
The mapping of the modifier keys looks like this:
#fn - ignored Control_L 7 5 0 # C= key (not really) Alt_L 7 2 16384 # CTRL key (kinda) Meta_L 7 5 8192 # “standalone” C= key # Meta_R - ignored
Alt_R - works just like Alt_L
### Spaaaaaaaaace\!
<span class="eimg sml">
</span>
space 7 4 0 # space
### The Cursor Keys
The (terrible) cursor keys on the Commodore 64 can be properly “flattened” into the vastly superior cursor keys of the mac:
Left 0 2 1 # shift-CRSR LEFT/right Up 0 7 1 # shift-CRSR UP/down Down 0 7 0 # CRSR up/DOWN Right 0 2 0 # CRSR left/RIGHT
And that should do it. Except…
# More Control?
The Commodore 64 has a few more keys that do special things when combined with CTRL. Most of these are simply duplicates
of action keys, but there are a few that are unique and a few others that are worth mapping “just because”.
The [Commodore 128 System Guide](https://www.commodore.ca/manuals/128_system_guide/toc.htm) has
an [excellent table](https://www.commodore.ca/manuals/128_system_guide/app-i.htm) listing all of the possible control
codes, along with key mappings for those that have them (and whether those mappings work on the C64 or the C128, or both).
The key information from this are the following combinations:
| `CTRL key` | Purpose | Map? |
| :---: | :---- |:----:|
| **`CTRL C`** | STOP | no |
| **`CTRL E`** | Set text color to white | no |
| **`CTRL H`** | Disable SHIFT/C= toggle | YES |
| **`CTRL I`** | Enable SHIFT/C= toggle | YES |
| **`CTRL J`** | Carriage return | no |
| **`CTRL M`** | RETURN | no |
| **`CTRL N`** | Go to lowercase | YES |
| **`CTRL Q`** | Cursor down | no |
| **`CTRL S`** | HOME | no |
| **`CTRL T`** | DEL | no |
| **`CTRL /`** | Set text color to red | no |
| **`CTRL ]`** | Cursor right | no |
| **`CTRL ↑`** | Set text color to green | no |
I will admit my choices as to which of these to map and which to ignore are arbitrary, but it is my mapping, and here’s what
I’ll add to my vkm:
dead_circumflex 4 1 4096 # option I = CTRL I abovedot 3 5 4096 # option H = CTRL H dead_perispomeni 4 7 4096 # option N = CTRL N ```
And now I’m done with my keyboard map.
The Final Mapping
The final mapping looks like this:
You can find the final VKM file hosted on Github.
In Summary
With the journey to create the VKM done, in the next episode I’ll summarize everything into a general how-to guide.
Explore more of the Challenge Series
Explore more of the Vice Vkm Series
#retro-computing #vice #emulators #commodore