Arnold TNG is yet another CPC emulator for Linux, with a number of new
features for power users:
The CPC's Z80A CPU runs at 4 MHz. Imagine what would happen if it became more powerful: not via a higher clockspeed, but by completing instructions faster. So a 'NOP' instruction, which normally takes 4 cycles to complete (1 microsecond, Warp 1), might suddenly take only 1 cycle (0.25 microseconds, Warp 4), or even just 0.25 cycles (Warp 16). Interrupts still occur 300 times a second, the CRTC still draws 50 frames per second, but the Z80A simply provides much more computational power. In Arnold TNG, you can always press F7 to accelerate up to Warp 16, and F6 to slow down again. In fullscreen mode, the current Warp factor is shown on the right side.
The following things work at Warp >=2:
The following things do not work at Warp >=2:
Examples:
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Arnold TNG uses the power of today's GPUs from nVIDIA
and ATI to provide smooth OpenGL based zooming. Just press F2 to enter
fullscreen mode, then
use Ctrl+CursorUp to zoom in and Ctrl+CursorDown to zoom out. This way
you can optimally fit the scene to the screen, no matter if it's a
shrunk-down game or an overscan demo. Arnold TNG also detects the
physical resolution of your screen, and ensures that the CPC screen is
displayed with the correct aspect ratio, no matter if you are sitting
in front of a 4:3 or 16:10 screen.
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Despite their low resolution, many CPC games (Ghosts'n'Goblins..) and demos look great because they run with perfect smoothness and update the screen 50 times per second, in sync with the screen refresh rate. This normally doesn't work with emulators, since today's screens have a higher refresh rate, causing a loss of smoothness. Arnold TNG can make use of the fact that most screens can operate in a certain refresh rate range, for TFTs that's usually 60-75 Hz (most TFTs display the current refresh rate in the on screen menu). To get perfect smoothness, you need three things:
First, set your screen to the lowest refresh rate it
can support (since
TFT screens don't flicker, a lower refresh rate doesn't matter). E.g.
for nVIDIA cards, the recipe is as follows:
You need to edit the /etc/X11/xorg.conf file. Before making any changes
though, back it up so you can restore it if you break anything.
cp /etc/X11/xorg.conf /etc/X11/xorg.backup-working.conf
Now open up the file as root to edit it. Under Section "Screen", there will be a SubSection "Display" area. On the Modes line, put your desired resolution(s) followed by an underscore and then the desired refresh rate. For example, if you want to run at 1280x1024 at 60 Hz, put:
Modes "1280x1024_60"
Normally, though, this won't override the refresh rate if your monitor is telling the driver something else. To force the driver to ignore the monitor, paste this inside Section "Screen":
Option "UseEDIDFreqs" "False"
Finally, search for VertRefresh and make sure you are
not trying to set
a refresh rate higher than the largest number in that field. Always
make sure your monitor is actually capable of the resolution and
refresh rate combination you select before you override it manually or
you may permanently damage it. Save the file, restart X with
Ctrl-Alt-Backspace and you should be in your desired resolution/refresh
rate combination.
Second, use /usr/bin/nvidia-settings to enable all 'Sync to VBlank' options you can find.
Third, run Arnold TNG with the refresh rate you set above plus 2, usually 62 frames per second:
./arnold -fps 62
As a result, you should now have perfect smoothness with linear interpolated scaling in fullscreen mode, which makes the emulator essentially indistinguishable from a real CPC. With one side-effect: the CPC runs 20% faster, which makes fast games like Zap'T'Balls a bit more challenging ;-)
In case you want to play on your notebook in the train and don't have you joystick with you, simply press F5 to toggle joystick emulation. Then the joystick is mapped to the cursor keys, the left Window key is Fire1, the left Alt key is Fire2.
Arnold for Linux is maintained by Nurgle at this site. Until Nurgle has finished the next release, you can download the pre-compiled beta version of Arnold TNG here:
If you decide to re-run ./configure, you currently
need to add
-DHAVE_GL and -lGL to the makefile manually.
In case you want to know what has changed, here are the actual patches
applied:
arnold.c
Here is a usage example based on the game Zap'T'Balls - The Advanced Edition:
Have fun with your CPC!
The game Driller by
Incentive Software introduced the fascinating 'Freescape' 3D engine,
which took the Z80A to its limits, and was just a bit too slow. Now you
can enjoy the game at Warp 16: Press X/S to set the step size to 50,
press Z/A to set the rotation angle to 5 degrees, then use the cursor
keys and N/M to fly around in a 3D world that is suddenly so smooth,
that Amiga and Atari ST would be jealous. Note that the clock in the
top
right corner does not run faster, so you still got all the time you
need to complete the game. The same holds for follow-up games like
Total Eclipse. 
The famous racer
Burnin' Rubber does not adapt like Driller above.
At Warp 2, it runs not only twice as smooth, but also twice as fast.
Surprisingly, the doubled smoothness
ensures that the game is still perfectly playable and great fun. It's
comparable to Nintendo's F-Zero concept: once you finished the tracks,
you enter the next, faster league. The same holds for other cool CPC
racers like Wec Le Mans, Chase HQ or Power Drift: The higher the Warp
factor,
the better they look. And how fast can you go?