Choosing HIMEM.SYS vs EMM386.EXE for Conventional Memory Optimization in MS‑DOS
Decide whether to load only HIMEM.SYS or combine it with EMM386.EXE to create Upper Memory Blocks, and see how to configure CONFIG.SYS and verify the result.
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msdosReclaiming the 640KB Limit: Mastering the Upper Memory Area in MS-DOS
Learn how to bypass the 640KB conventional memory limit in MS-DOS by utilizing HIMEM.SYS and EMM386 to move drivers into the Upper Memory Area (UMA).
FAT12 Cluster Chaining and Partition Size Constraints in MS-DOS
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.
Diagnosing and Fixing MS‑DOS ‘Insufficient Memory’ Errors: A Practical Guide
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.
Unlocking More RAM in MS‑DOS: How HIMEM.SYS and XMS Break the 640 KB Barrier
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.
Fixing ‘Out of Memory’ in MS‑DOS: A Step‑by‑Step Diagnostic Guide
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.
Sector‑by‑Sector Backup of Floppy Disks with MS‑DOS DISKCOPY
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.
Speeding Up MS‑DOS Workflows with DOSKEY Aliases
Learn how to create, persist, and use DOSKEY aliases in MS‑DOS, including correct syntax, macro arguments, batch‑file considerations, and a practical AUTOEXEC.BAT example.
INT 21h 4E01h vs COM/EXE: Determining the Maximum Command‑Line Length
Goal To identify the absolute maximum length of a command‑line string that can be delivered to a COM or EXE program via INT 21h function 4E01h, while accounting for documented PSP limits and possible variations across DOS releases. Constraints The PSP reserves a single byte at offset 0x80 to store the length of the command line, and the string itself is null