This package allows MS-DOS programs to be started in Linux. A virtual machine (the DOS box) provides the necessary BIOS functions and emulates most of the chip devices (e.g. timer, interrupt- and keyboard controler).
You will find the sources in the series "sources".
Documentation can be found in '/usr/doc/packages/dosemu' and in the man page, as well as in the sources.
If you wish to allow non-root users to run the emulator, you must enter their names in the file '/etc/dosemu.users'. Even so, some DOS programs will run only if DOSEMU was started by root. Please note as well that you should only allow 'trusted users' to use a suid-root DOSEMU binary, as it inherently permits hardware access that would otherwise be forbidden to 'normal' users. However, running a non-suid-root DOSEMU binary (low feature) won't impact your system more than any other Linux application.
The parameter $_hogthreshold in '/etc/dosemu.conf' defines how often an 'idling' DOSEMU should return the CPU to Linux and its default value '(1)' means 'all power to Linux'. The higher this value is, the more more CPU power is dedicated to DOSEMU. The value '(0)' disables this feature completely, hence: 'all power to DOSEMU'. If that isn't fast enough, you (running UID root) can get maximum performance with
nice -19 dos -D-a 2>/dev/null
Don't be surprised though if the other Linux processes then run very sluggishly.
On sensitive systems you _never_ should offer a suid-root DOSEMU world readable, because even if the '$_secure' option in /etc/dosemu.conf is set, its not avoidable that some DPMI-clients (most likely Dos4gw based ones) may succeed in accessing the whole user space (including DOSEMU code) and thus gain root access. A comfortable solution is to have two copies of the DOSEMU binary, a non-suid-root one for world access and a suid-root one (protected by file permissions) only available to trusted users.
In order to start dosemu, you will need a bootable hdimage. Please read the file QuickStart, cd to /var/lib/dosemu and start ./setup-hdimage. Under X you may now start ./setup-dosemu, which is a Tcl/Tk based configuration tool with online help (you only need the menu entry 'Runtime configuration'). ATTENTION: if you have already used dosemu before version 0.97.x: the configuration has changed fundamentally, so please read the docs (/usr/doc/packages/dosemu/*) even though you think you know what you are doing :-) It is possible though to use the old configuration files (needs to be configured explicitly). Look into QuickStart on how to do it.