FreeDOSDeep Dive 7 min read
DOS File Handles: Open, Read, Inherit, and Redirect I/O
Follow the DOS INT 21h handle API from open through close, and understand how handle-based I/O enables command-line redirection.
#freedos#ms-dos#int-21h
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#int-21h
4 posts
FreeDOSDeep Dive 7 min read
DOS INT 21h Function 59h: Read Extended Error Diagnostics
Capture DOS error class, suggested recovery, and locus immediately after a failed call, while preserving registers and avoiding stale diagnostics.
#freedos#dos#int-21h
Read more FreeDOSDeep Dive 7 min read
FreeDOS INT 21h IOCTL: Device Status and Control Requests
Use DOS function 44h carefully: inspect handles, distinguish character and block IOCTLs, handle readiness and redirection, and avoid undocumented driver commands.
#freedos#dos#ioctl
Read more FreeDOSDeep Dive 8 min read
DOS Version Reporting: INT 21h, FreeDOS CALLVER, and MS-DOS SETVER
Trace DOS version queries through INT 21h, FreeDOS VERSION and CALLVER, and MS-DOS SETVER, separating reported compatibility from actual capabilities.
#freedos#ms-dos#int-21h
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