ReadMeFeed / Community knowledge
Real questions. Useful conversations. Find the people who know your stack.
Developer tools · #msdos
The 12-bit FAT table dictates how MS-DOS tracks file clusters, imposes hard partition size limits, and why a single corrupted entry can collapse an entire file chain.
When a DOS program refuses to start with “Insufficient memory” or “Program too big to fit in memory”, the culprit is often conventional memory exhaustion. This guide walks through MEM diagnostics, CONFIG.SYS ordering, and UMB/extended‑memory tricks to reclaim the 640 KB of usable RAM.
Learn how to use the DEVICEHIGH directive in CONFIG.SYS to load device drivers into the Upper Memory Area, freeing conventional memory for DOS programs.
Step-by-step guide to freeing conventional memory in MS-DOS 5.0–6.22 by loading the DOS kernel into the HMA and moving drivers/TSRs into UMBs using HIMEM.SYS and EMM386.EXE. Includes CONFIG.SYS and AUTOEXEC.BAT examples, MEM verification commands, and recovery procedures for boot failures.
MS‑DOS limits programs to 640 KB of conventional memory. By loading HIMEM.SYS and using the XMS interface you can access memory above 1 MB, enabling larger applications and better multitasking. This guide walks through the configuration, usage, and trade‑offs of XMS in a real‑world example.
MS-DOS TSRs achieved background tasks by hooking interrupt vectors and staying resident via INT 21h/31h. This blog explains the mechanism, the non-reentrant kernel's InDOS flag constraint, and includes a minimal assembly example you can run in DOSBox.
When MS‑DOS reports ‘Out of memory’ despite 640 KB RAM, the problem is usually conventional memory exhaustion. This guide walks through MEM, HIMEM.SYS, DOS=HIGH, DEVICEHIGH, and EMM386.EXE to reclaim space and get applications running.
Choosing the right cluster size in MS-DOS FAT16 is a balance between disk performance and wasted slack space. Learn how to calculate waste and pick the right format.
Learn how to use DISKCOPY to clone a floppy disk at the sector level, verify the copy with FC /B, and handle common errors and recovery steps.