ZEsarUX Emulator

[doorsfan]

That's not a problem with ubuntu, but seems a problem with your compilation.
Show me please the output of the configure command

cd ~/zesarux/ ; git pull ; cd src ; ./configure
Already up to date.

Configuration script for ZEsarUX

Initial CFLAGS=
Initial LDFLAGS=
Checking Operating system ... GNU/Linux
Checking for gcc compiler ... /usr/bin/gcc
Checking size of char ... 1
Checking size of short ... 2
Checking size of int ... 4
Checking Little Endian System ... ok
Checking for stdout functions ... found
Checking for simpletext functions ... found
Checking for fbdev functions ... found
Checking for cursesw libraries ... found
Checking for curses libraries ... found
Checking for aa libraries ... not found
Checking for caca libraries ... not found
Checking for SSL libraries ... disabled
Checking for xwindows libraries ... found
Checking for xwindows extensions ... found
Checking for xwindows vidmode extensions ... found
Checking for posix threads ... found
Checking for audio dsp ... found
Checking for audio alsa ... found
Checking for audio pulse ... found
Checking for coreaudio ... not found
Checking for Cocoa Mac OS X GUI ... not found
Checking for sdl libraries ... not found
Checking for libsndfile ... not found
Checking for linux real joystick ... found

Final CFLAGS= -Wall -Wextra -fsigned-char -I/usr/include/ncursesw -D_GNU_SOURCE -D_DEFAULT_SOURCE
Final LDFLAGS= -lncursesw -lX11 -L/usr/X11R6/lib -L/opt/X11/lib -lXext -lXxf86vm -lpthread -lasound -lpulse -lpulse-simple -lpthread
Creating Makefile
Creating compileoptions.h

Config files successfully generated by ./configure

 Enabled Video output drivers: stdout simpletext curses cursesw xwindows fbdev null
 Disabled Video output drivers: aa caca cocoa sdl 
 Enabled Audio output drivers: dsp alsa pulse null
 Disabled Audio output drivers: coreaudio sdl 
 Enabled Audio File output drivers: raw 
 Disabled Audio File output drivers: wav 
 Pthreads support: yes
 SSL support: no
 Remote command protocol support: yes
 Linux real joystick support: yes
 MEMPTR emulation: no
 Visual memory option: no
 CPU statistics option: no
 Raspberry extensions: no
 Contended memory emulation: yes
 Putpixel cache: yes
 Spectrum default core: Normal

Install prefix: /usr/local