RetroPie DOSBox Notes

Config File

The DOSBox config file is at ~/.dosbox/dosbox-SVN.conf and the mapper file is mapper-SVN.map

The ~/.dosbox/ directory is a symlink to /opt/retropie/configs/pc/ directory

C Drive

I put my C drive in ~/RetroPie/roms/DOS and then edit the launcher RetroPie/roms/pc/+Start\ DOSBox.sh to have the line:

    params=(-c "@MOUNT C /home/pi/RetroPie/roms/DOS" -c "@C:")

This keeps the PC menu in RetroPie tidy.

Per-game Config

    params=(-conf "~/.dosbox/game.conf" -c "@MOUNT C /home/pi/RetroPie/roms/DOS" -c "@C:")

To have a custom key map, in that config file, set:

mapperfile=mapper-game.map

Keymapper

Good ideas:

• mod3 = Select
• Shutdown = Start mod3
• Cycles Down = L2 mod3
• Cycles Up = R2 mod3

Logitech F710:

mod_3 "stick_0 button 8" 
hand_shutdown "key 290 mod1" "stick_0 button 9 mod3" 
hand_cycledown "stick_0 button 6 mod3" "key 292 mod1" 
hand_cycleup "key 293 mod1" "stick_0 button 7 mod3" 

Should probably make a convention like:

• L2 = y
• R2 = n
• Select = Esc
• Start = Enter

Aspect Ratio

To get games to display in the correct aspect ratio:

windowresolution=1024x768
output=overlay
aspect=true

Setting output=opengl does not harm performance and applies bilinear smoothing to make things look nicer, though it also renders a mouse cursor in the top left corner which is rather annoying.

Setting windowresolution=1280x960 looks nicer but performance suffers for more complex games. Maybe this is OK to use with less demanding games.

Setting scaler=normal2x doesn't seem to make any performance difference, unsure if it makes a graphical difference either. Even on weaker games, scaler=normal3x affects performance.

Performance

I always configure my DOSBox with a fixed cycles count like:

core=auto
cputype=auto
cycles=20000
cycleup=1000
cycledown=1000

Doom maxes out the CPU at about 21000 cycles, which gives about 21fps, about the performance of a 486-66 according to the Doom Benchmark - https://www.complang.tuwien.ac.at/misc/doombench.html

Performance depends on the game, OMF2097 performs well on its "Pentium" setting with only 12500 cycles. IIRC from using real hardware, that setting actually did require a Pentium or faster.

Probably worth playing with cycles=max with some games. In Doom this dropped 4fps. In OMF2097 it makes the game so fast as to be unplayable.

Compiling from Source

The binaries RetroPie provides are compiled with the Pi 2 compiler flags, but recompiling on a Pi 3 uses different flags, which appears to give a boost in performance. I haven't benchmarked this.

Mouse control with analog stick (PS3)

Download and compile joymapper: https://sourceforge.net/projects/linuxjoymap/

Find device ID:

cat /proc/bus/input/devices

I: Bus=0003 Vendor=054c Product=0268 Version=0111
N: Name="Sony PLAYSTATION(R)3 Controller"
P: Phys=usb-bcm2708_usb-1.3.2/input0
S: Sysfs=/devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3.2/1-1.3.2:1.0/0003:054C:0268.0001/input/input2
U: Uniq=
H: Handlers=js0 event2 
B: PROP=0
B: EV=1b
B: KEY=7 0 0 0 0 0 0 0 0 0 0 0 0 ffff 0 0 0 0 0 0 0 0 0
B: ABS=7fffff00 27
B: MSC=10

Example PS3 mouse mapping for DOSBox:

# General Mouse Mapping for DOSBox

# Map Mouse
axis vendor=0x054c product=0x0268 src=0 target=mouse axis=0
axis vendor=0x054c product=0x0268 src=1 target=mouse axis=1
button vendor=0x054c product=0x0268 src=14 target=mouse button=0
button vendor=0x054c product=0x0268 src=15 target=mouse button=1

# Navigation
button vendor=0x054c product=0x0268 src=0 target=kbd button="esc"
button vendor=0x054c product=0x0268 src=3 target=kbd button="enter"
button vendor=0x054c product=0x0268 src=12 target=kbd button="space"

button vendor=0x054c product=0x0268 src=4 target=kbd button="up"
button vendor=0x054c product=0x0268 src=5 target=kbd button="right"
button vendor=0x054c product=0x0268 src=6 target=kbd button="down"
button vendor=0x054c product=0x0268 src=7 target=kbd button="left"

To use the mouse, DOSBox needs to capture it. This can be done by pressing CTRL+F10 or left-clicking.

Example launcher for Albion:

#!/bin/bash
sudo /home/pi/joymap/loadmap /home/pi/RetroPie/roms/pc/dosbox-map/mouse.map &
/opt/retropie/emulators/dosbox/bin/dosbox -c "mount c /home/pi/RetroPie/roms/pc" -c "c:" -c "cd ALBION" -c "LAUNCH.EXE" -c "exit" 
sudo killall loadmap
sleep 1

• https://retropie.org.uk/forum/topic/2032/dosbox-mapping-mouse-to-ps3-analog-stick/
• http://blog.petrockblock.com/forums/topic/mapping-a-game-controller-in-kodi/#post-106586

Mouse control with analog Stick (Logitech F710)

This isn't working, the mouse tries to stay in one corner and is way too fast. It also seems you need to map every key you want to use, not just the mouse axes. Kinda thinking this is no good for me.

Device

I: Bus=0003 Vendor=046d Product=c21f Version=0305
N: Name="Logitech Gamepad F710"
P: Phys=usb-3f980000.usb-1.2/input0
S: Sysfs=/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1-1.2:1.0/input/input3
U: Uniq=
H: Handlers=event3 js0 
B: PROP=0
B: EV=20000b
B: KEY=7fdb0000 0 0 0 0 0 0 0 0 0
B: ABS=3001b
B: FF=1 7030000 0 0

Mapper

~/.dosbox/mouse.map

# left analog left/right
axis vendor=0x046d product=0xc21f src=0 target=mouse axis=0
# left analog up/down
axis vendor=0x046d product=0xc21f src=1 target=mouse axis=1
# L3 = left click
button vendor=0x046d product=0xc21f src=11 target=mouse button=0
# R3 = left clock
button vendor=0x046d product=0xc21f src=12 target=mouse button=1

Launcher

Street Rod.sh

#!/bin/bash
sudo /home/pi/joymap/loadmap /home/pi/.dosbox/mouse.map &
/opt/retropie/emulators/dosbox/bin/dosbox -c "@MOUNT C /home/pi/RetroPie/roms/DOS" -c "@C:" -c "@CD SR1" -c "@SR.EXE" -c "@EXIT"
sudo killall loadmap
sleep 1

References

• https://www.reddit.com/r/RetroPie/comments/50q04s/getting_320x200_dos_games_to_display_correctly/
• https://retropie.org.uk/forum/topic/2032/dosbox-mapping-mouse-to-ps3-analog-stick