====== Cómo Utilizar Los Puertos Serie Con Dosbox ======

===== Introducción =====
En ocasiones necesitamos emular MS-DOS para ejecutar aplicaciones que llevan tiempo usándose en la empresa, que no tienen un reemplazo inmediato en Linux, y es imprescindible hallarle una solución al problema para seguir con la migración. O como en el caso que referiremos a continuación, la aplicación ya no se comercializa más, y el problema sucede cuando no hay tiempo para pensar en programar alternativas.

Existen al menos dos paquetes de software para emular MS-DOS: DOSBox y DOSEMU. Ambas tienen ventajas y desventajas. En nuestro caso particular, hemos hallado más práctico el DOSBox y a él nos referiremos.

Sucedió que necesitábamos lanzar una vieja aplicación MS-DOS  que maneja relojes RTA600 de marcar entradas y salidas con tarjetas magnéticas. Por tanto, la tarea se enmarcaba en cómo utilizar los puertos serie de la PC emulando MS-DOS.

===== Instalación =====
Debian 6 trae el paquete. Lo instalamos con "aptitude install dosbox" (sin comillas!), y a continuación pasamos a mirar la configuración. 
===== Configuración =====
Este es un ejemplo de fichero de confguración:

 # This is the configurationfile for DOSBox 0.73.

 # Lines starting with a # are commentlines.

 # They are used to (briefly) document the effect of each option.


 [sdl]

 #       fullscreen: Start dosbox directly in fullscreen.

 #       fulldouble: Use double buffering in fullscreen.

 #   fullresolution: What resolution to use for fullscreen: original or fixed size (e.g. 1024x768).

 # windowresolution: Scale the window to this size IF the output device supports hardware scaling.

#           output: What video system to use for output.

#                   Possible values: surface, overlay, opengl, openglnb.

#         autolock: Mouse will automatically lock, if you click on the screen.

#      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.

#     usescancodes: Avoid usage of symkeys, might not work on all operating systems.


fullscreen=false

fulldouble=false

fullresolution=original

windowresolution=original

output=surface

autolock=true

sensitivity=100

waitonerror=true

priority=higher,normal

mapperfile=mapper.txt

usescancodes=true


[dosbox]

# language: Select another language file.

#  machine: The type of machine 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_s3

captures=capture

memsize=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,the scaler will be used even if the result might not be desired.

#            Possible values: none, normal2x, normal3x, advmame2x, advmame3x, advinterp2x, advinterp3x, hq2x, hq3x, 2xsai, super2xsai, supereagle, tv2x, tv3x, rgb2x, rgb3x, scan2x, scan3x.


frameskip=0

aspect=false

scaler=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 increase/decrease with keycombo.

# cycledown: Setting it lower than 100 will be a percentage.


core=auto

cputype=auto

cycles=auto

cycleup=500

cycledown=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: 22050, 44100, 48000, 32000, 16000, 11025, 8000, 49716.

# blocksize: Mixer block size, larger blocks might help sound stuttering but sound will also be more lagged.

#            Possible values: 2048, 4096, 8192, 1024, 512, 256.

# prebuffer: How many milliseconds of data to keep on top of the blocksize.


nosound=false

rate=22050

blocksize=2048

prebuffer=10

[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. See README for details.


mpu401=intelligent

mididevice=default

midiconfig=


[sblaster]

#  sbtype: Type of sblaster to emulate.

#          Possible values: sb1, sb2, sbpro1, sbpro2, sb16, 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: 22050, 49716, 44100, 48000, 32000, 16000, 11025, 8000.


sbtype=sb16

sbbase=220

irq=7

dma=1

hdma=5

sbmixer=true

oplmode=auto

oplemu=default

oplrate=22050

[gus]

#      gus: Enable the Gravis Ultrasound emulation.

#  gusrate: Sample rate of Ultrasound emulation.

#           Possible values: 22050, 44100, 48000, 32000, 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=false

gusrate=22050

gusbase=240

gusirq=5

gusdma=3

ultradir=C:\ULTRASND


[speaker]

# pcspeaker: Enable PC-Speaker emulation.

#    pcrate: Sample rate of the PC-Speaker sound generation.

#            Possible values: 22050, 44100, 48000, 32000, 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: 22050, 44100, 48000, 32000, 16000, 11025, 8000, 49716.

#    disney: Enable Disney Sound Source emulation. (Covox Voice Master and Speech Thing compatible).


pcspeaker=true

pcrate=22050

tandy=auto

tandyrate=22050

disney=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).

#               Possible values: auto, 2axis, 4axis, 4axis_2, fcs, ch, none.

#        timed: enable timed intervals for axis. (false is old style behaviour).

#     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=auto

timed=true

autofire=false

swap34=false

buttonwrap=true


[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.

#          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=directserial realport:ttyS0

serial2=directserial realport:ttyS1

serial3=directserial realport:ttyS2

serial4=directserial realport:ttyS3


[dos]

#            xms: Enable XMS support.

#            ems: Enable EMS support.

#            umb: Enable UMB support.

# keyboardlayout: Language code of the keyboard layout (or none).


xms=true

ems=true

umb=true

keyboardlayout=auto


[ipx]

# ipx: Enable ipx over UDP/IP emulation.

ipx=false

[autoexec]

# Lines in this section will be run at startup.

mount c /home/personal/Documentos/RTA600

mount e /home/personal/Descargas


(Fin del fichero de configuración)


Como vemos, la solución consiste en declarar siguientes líneas en el fichero de configuración de DOSBox:

 serial1=directserial realport:ttyS0

 serial2=directserial realport:ttyS1

 serial3=directserial realport:ttyS2

 serial4=directserial realport:ttyS3


Ojo, que debo modificar el fichero de configuración DOSBox del usuario que utilice la aplicación. Si se ejecuta como administrador, hay que modificar el del usuario root.


===== Notas =====

Por supuesto que para lanzar una aplicación habrá que tocar algunas otras cosas. Por ejemplo, habrá que declarar dónde pondré a "C:". Eso lo veo en las líneas mount.