Memory models, FAT, interrupts, and the open-source continuation of the original PC OS.
How DEVLOAD emulates DEVICE and DEVICEHIGH at runtime, assigns block devices, reports memory use, and reveals which drivers still require boot-time setup.
How FreeDOS SHARE implements DOS open-sharing rules, tracks byte-range locks by process, reports conflicts, and fits into a practical compatibility test.
How FreeDOS SWSUBST combines SUBST and JOIN, edits DOS drive mappings, exposes CDS state, and avoids breaking programs that cache drive assumptions.
A hardware-aware guide to FDAPM information, idle modes, standby, suspend, poweroff, reboot, disk handling, and cache safety on FreeDOS.
How FreeDOS LBACACHE accelerates BIOS sector reads, uses XMS, observes writes without delaying them, reports hit rates, and unloads safely.
How FreeDOS NANSI interprets console escape sequences, colors, cursor controls and optional key redefinition, plus loading, testing, and safety boundaries.
How COUNTRY, KEYB, DISPLAY, MODE and CHCP coordinate FreeDOS locale data, keyboard input and screen glyphs without confusing bytes with Unicode.
How DPMI hosts give DOS applications selectors, linear memory, real-mode callbacks, interrupts, exceptions, and virtual memory without replacing DOS.
How FreeDOS reads and writes FAT32 volumes, including BPB fields, 28-bit cluster chains, root-directory changes, FSInfo hints, size limits, and repair.
A diagnostic path for missing DPMI hosts, linear-memory exhaustion, page faults, invalid selectors, swap files, extenders, TSR conflicts, and bad RAM.