DOSBox-X vs Hercules

DOSBox-X is a free, open-source DOS emulator for running DOS applications and games on Linux, macOS and Windows. It also supports DOS-based Windows guests, including Windows 3.x and Windows 9x/Me. The project emphasizes general emulation and accurate hardware behavior, with DOS/V services and emulation for NEC PC-98, AX and J-3100 systems. A graphical configuration tool and many virtual-machine options let users adjust the emulated environment. DOSBox-X provides up to 100 save slots, with automatic saving for selected programs or at user-defined intervals. Its emulated NE2000 adapter supports guest networking through PCAP and Slirp backends. Printing can use parallel ports and real or emulated printers, with PostScript or PNG output. Launching host applications from the emulator is disabled by default for security and can be enabled through configuration or a command-line option. The project describes use for DOS software, historical preservation, testing and continued DOS development; emulating Pentium 4-or-higher CPUs and post-2000 PC hardware are listed as non-goals.

Hercules is a free, open-source emulator for IBM System/370, ESA/390, and 64-bit z/Architecture mainframes. It lets a PC execute programs designed for those systems and represents mainframe I/O devices with PC resources, including DASD files and local tn3270 sessions. It does not provide an operating system, so users must supply one or run a standalone program. With legally licensed software, it can run z/OS, z/VM, z/VSE, OS/390, VM/ESA, VSE/ESA, and older related IBM operating systems. Features include dynamic reconfiguration, an integrated console, interpretive execution, debugging tools, and snapshots and restore. Guest TCP/IP networking can connect to the host through TUN/TAP and hercifc, and multiple instances can share devices. Hercules is licensed under the Q Public Licence and runs on Linux, macOS, and Windows; the host list also names Solaris and FreeBSD. Documented unsupported areas include ESCON, FICON, PR/SM, coupling links, and several z/Architecture facilities. Its FAQ says it has not claimed production capability and was intended as a system programmer's toy.