First post, by mothergoose729
I spent a lot of time getting DOSBOX to work with old CRT monitors in this thread.
The Quest for Pixel Perfect DOS Emulation
The tl;dr there is that modern LCD monitors struggle with DOS games because of the weird frame rates and resolutions that they used. So much so that "the real thing" (well a CRT monitor in particular) can be a significantly better experience than emulation in some respects.
I recently splurged on a fancy new gaming monitor, and so naturally one of the first things I did was use it to play DOS games 😁.
https://www.dell.com/en-us/shop/alienware-34- … tor-accessories
(this particular model is also an OLED, which is nice for other reasons).
I speculated in that thread that a modern monitor with gsync could do even better though. Basically gsync (and the similar tech free sync) will adjust the framerate of the display to match a the content. A gsync or free sync display with a wide sync window can handle all kinds of oddball framerates perfectly smoothly - even better than real hardware even, as even a CRT monitor will have judder if the frame rate of the game is not well in sync with the refresh rate of the game.
A good example is something like prehistorik 2, which runs at 15 fps for some reason but has a display mode with a 70hz refresh rate, and so even on real hardware there is some judder and it looks choppy as hell. My gsync monitor handles the loading screen and map preview well, which run at 70ish fps, and the main game which runs at 15 fps, even better than my real DOS machine which has some judder and some skipping here and there when the game does whatever it does that makes it drop frames (it drops frame in DOSBOX too, it's just that gsync doesn't used a fixed refresh rate so it's mostly fine).
Gsync also has basically no latency penalty compared vsync or double buffering. So compared to emulating with a CRT like in my other thread, it feels like the latency is actually a bit better.
Another cool feature on modern Nvidia/AMD graphics is that they support driver level integer scaling, which has the potential to be faster and reduce latency compared to software scaling and especially compared to hardware scaling on your display.
So I fired up DOSBOX, and using the settings below I got basically perfect emulation. Smooth frame rate, latency felt low, and crispy unfiltered pixels. No screen tearing, no judder, all DOS gaming goodness.
In my nvidia control panel I enabled gsync for windows and full screen applications, enabled integer scaling, ultra low latency mode, and set a frame limit of 3pfs below my monitors max refresh rate (in my case 172fps). You want to set the vysnc in the driver to global "on" and you went to disable buffering and vsync in your applications (like dosbox).
Dosbox settings -
# This is the configuration file for DOSBox 0.74-3. (Please use the latest version of DOSBox)# Lines starting with a # are comment lines and are ignored by DOSBox.# They are used to (briefly) document the effect of each option.[sdl]# fullscreen: Start dosbox directly in fullscreen. (Press ALT-Enter to go back)# fulldouble: Use double buffering in fullscreen. It can reduce screen flickering, but it can also result in a slow DOSBox.# fullresolution: What resolution to use for fullscreen: original, desktop or fixed size (e.g. 1024x768).# Using your monitor's native resolution (desktop) with aspect=true might give the best results.# If you end up with small window on a large screen, try an output different from surface.# On Windows 10 with display scaling (Scale and layout) set to a value above 100%, it is recommended# to use a lower full/windowresolution, in order to avoid window size problems.# windowresolution: Scale the window to this size IF the output device supports hardware scaling.# (output=surface does not!)# output: What video system to use for output.# Possible values: surface, overlay, opengl, openglnb, ddraw.# autolock: Mouse will automatically lock, if you click on the screen. (Press CTRL-F10 to unlock)# sensitivity: Mouse sensitivity.# waitonerror: Wait before closing the console if dosbox has an error.# priority: Priority levels for dosbox. Second entry behind the comma is for when dosbox is not focused/minimized.# pause is only valid for the second entry.# Possible values: lowest, lower, normal, higher, highest, pause.# mapperfile: File used to load/save the key/event mappings from. Resetmapper only works with the defaul value.# usescancodes: Avoid usage of symkeys, might not work on all operating systems.fullscreen=truefulldouble=falsefullresolution=originalwindowresolution=originaloutput=surfaceautolock=truesensitivity=100waitonerror=truepriority=higher,normalmapperfile=mapper-0.74-3.mapusescancodes=true[dosbox]# language: Select another language file.# machine: The type of machine DOSBox tries to emulate.# Possible values: hercules, cga, tandy, pcjr, ega, vgaonly, svga_s3, svga_et3000, svga_et4000, svga_paradise, vesa_nolfb, vesa_oldvbe.# captures: Directory where things like wave, midi, screenshot get captured.# memsize: Amount of memory DOSBox has in megabytes.# This value is best left at its default to avoid problems with some games,# though few games might require a higher value.# There is generally no speed advantage when raising this value.language=machine=svga_s3captures=capturememsize=16[render]# frameskip: How many frames DOSBox skips before drawing one.# aspect: Do aspect correction, if your output method doesn't support scaling this can slow things down!# scaler: Scaler used to enlarge/enhance low resolution modes. If 'forced' is appended,# then the scaler will be used even if the result might not be desired.# To fit a scaler in the resolution used at full screen may require a border or side bars,# to fill the screen entirely, depending on your hardware, a different scaler/fullresolution might work.# Possible values: none, normal2x, normal3x, advmame2x, advmame3x, advinterp2x, advinterp3x, hq2x, hq3x, 2xsai, super2xsai, supereagle, tv2x, tv3x, rgb2x, rgb3x, scan2x, scan3x.
frameskip=0aspect=truescaler=normal2x[cpu]# core: CPU Core used in emulation. auto will switch to dynamic if available and# appropriate.# Possible values: auto, dynamic, normal, simple.# cputype: CPU Type used in emulation. auto is the fastest choice.# Possible values: auto, 386, 386_slow, 486_slow, pentium_slow, 386_prefetch.# cycles: Amount of instructions DOSBox tries to emulate each millisecond.# Setting this value too high results in sound dropouts and lags.# Cycles can be set in 3 ways:# 'auto' tries to guess what a game needs.# It usually works, but can fail for certain games.# 'fixed #number' will set a fixed amount of cycles. This is what you usually# need if 'auto' fails. (Example: fixed 4000).# 'max' will allocate as much cycles as your computer is able to# handle.# Possible values: auto, fixed, max.# cycleup: Amount of cycles to decrease/increase with keycombos.(CTRL-F11/CTRL-F12)# cycledown: Setting it lower than 100 will be a percentage.core=autocputype=autocycles=maxcycleup=10cycledown=20[mixer]# nosound: Enable silent mode, sound is still emulated though.# rate: Mixer sample rate, setting any device's rate higher than this will probably lower their sound quality.# Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.# blocksize: Mixer block size, larger blocks might help sound stuttering but sound will also be more lagged.# Possible values: 1024, 2048, 4096, 8192, 512, 256.# prebuffer: How many milliseconds of data to keep on top of the blocksize.nosound=falserate=44100blocksize=1024prebuffer=75[midi]# mpu401: Type of MPU-401 to emulate.# Possible values: intelligent, uart, none.# mididevice: Device that will receive the MIDI data from MPU-401.# Possible values: default, win32, alsa, oss, coreaudio, coremidi, none.# midiconfig: Special configuration options for the device driver. This is usually the id of the device you want to use# (find the id with mixer/listmidi).# Or in the case of coreaudio, you can specify a soundfont here.# See the README/Manual for more details.mpu401=intelligentmididevice=defaultmidiconfig=[sblaster]# sbtype: Type of Soundblaster to emulate. gb is Gameblaster.# Possible values: sb1, sb2, sbpro1, sbpro2, sb16, gb, none.# sbbase: The IO address of the soundblaster.# Possible values: 220, 240, 260, 280, 2a0, 2c0, 2e0, 300.# irq: The IRQ number of the soundblaster.# Possible values: 7, 5, 3, 9, 10, 11, 12.# dma: The DMA number of the soundblaster.# Possible values: 1, 5, 0, 3, 6, 7.# hdma: The High DMA number of the soundblaster.# Possible values: 1, 5, 0, 3, 6, 7.# sbmixer: Allow the soundblaster mixer to modify the DOSBox mixer.# oplmode: Type of OPL emulation. On 'auto' the mode is determined by sblaster type. All OPL modes are Adlib-compatible, except for 'cms'.# Possible values: auto, cms, opl2, dualopl2, opl3, none.# oplemu: Provider for the OPL emulation. compat might provide better quality (see oplrate as well).# Possible values: default, compat, fast.# oplrate: Sample rate of OPL music emulation. Use 49716 for highest quality (set the mixer rate accordingly).# Possible values: 44100, 49716, 48000, 32000, 22050, 16000, 11025, 8000.sbtype=sb16sbbase=220irq=7dma=1hdma=5sbmixer=trueoplmode=autooplemu=compatoplrate=44100[gus]# gus: Enable the Gravis Ultrasound emulation.# gusrate: Sample rate of Ultrasound emulation.# Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.# gusbase: The IO base address of the Gravis Ultrasound.# Possible values: 240, 220, 260, 280, 2a0, 2c0, 2e0, 300.# gusirq: The IRQ number of the Gravis Ultrasound.# Possible values: 5, 3, 7, 9, 10, 11, 12.# gusdma: The DMA channel of the Gravis Ultrasound.# Possible values: 3, 0, 1, 5, 6, 7.# ultradir: Path to Ultrasound directory. In this directory# there should be a MIDI directory that contains# the patch files for GUS playback. Patch sets used# with Timidity should work fine.gus=falsegusrate=44100gusbase=240gusirq=5gusdma=3ultradir=C:\ULTRASND[speaker]# pcspeaker: Enable PC-Speaker emulation.# pcrate: Sample rate of the PC-Speaker sound generation.# Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.# tandy: Enable Tandy Sound System emulation. For 'auto', emulation is present only if machine is set to 'tandy'.# Possible values: auto, on, off.# tandyrate: Sample rate of the Tandy 3-Voice generation.# Possible values: 44100, 48000, 32000, 22050, 16000, 11025, 8000, 49716.# disney: Enable Disney Sound Source emulation. (Covox Voice Master and Speech Thing compatible).pcspeaker=truepcrate=44100tandy=autotandyrate=44100disney=true[joystick]# joysticktype: Type of joystick to emulate: auto (default), none,# 2axis (supports two joysticks),# 4axis (supports one joystick, first joystick used),# 4axis_2 (supports one joystick, second joystick used),# fcs (Thrustmaster), ch (CH Flightstick).# none disables joystick emulation.# auto chooses emulation depending on real joystick(s).# (Remember to reset dosbox's mapperfile if you saved it earlier)# Possible values: auto, 2axis, 4axis, 4axis_2, fcs, ch, none.# timed: enable timed intervals for axis. Experiment with this option, if your joystick drifts (away).# autofire: continuously fires as long as you keep the button pressed.# swap34: swap the 3rd and the 4th axis. Can be useful for certain joysticks.# buttonwrap: enable button wrapping at the number of emulated buttons.joysticktype=autotimed=trueautofire=falseswap34=falsebuttonwrap=false[serial]# serial1: set type of device connected to com port.# Can be disabled, dummy, modem, nullmodem, directserial.# Additional parameters must be in the same line in the form of# parameter:value. Parameter for all types is irq (optional).# for directserial: realport (required), rxdelay (optional).# (realport:COM1 realport:ttyS0).# for modem: listenport (optional).# for nullmodem: server, rxdelay, txdelay, telnet, usedtr,# transparent, port, inhsocket (all optional).# Example: serial1=modem listenport:5000# Possible values: dummy, disabled, modem, nullmodem, directserial.# serial2: see serial1# Possible values: dummy, disabled, modem, nullmodem, directserial.# serial3: see serial1# Possible values: dummy, disabled, modem, nullmodem, directserial.# serial4: see serial1# Possible values: dummy, disabled, modem, nullmodem, directserial.serial1=dummyserial2=dummyserial3=disabledserial4=disabled[dos]# xms: Enable XMS support.# ems: Enable EMS support.# umb: Enable UMB support.# keyboardlayout: Language code of the keyboard layout (or none).xms=trueems=trueumb=truekeyboardlayout=auto[ipx]# ipx: Enable ipx over UDP/IP emulation.ipx=false[autoexec]# Lines in this section will be run at startup.# You can put your MOUNT lines here.
tl;dr
Using gsync/freesync and driver level integer scaling can make DOS emulation even better than the real thing when it comes to smoothness/ frame pacing while keeping latency low and pixels crispy.
