[lDOS] Server call (int 21h function 5D00h) crashes on unsupported functions

Title	[lDOS] Server call (int 21h function 5D00h) crashes on unsupported functions
Author	E. C. Masloch
Created	2026-06-07 09:35:26 +0200 Jun Sun
State	closed

User stack frame functions and high functions (beyond 6Ch) would crash if called from a server call.

Reference: https://github.com/LoopZ/TheList/blob/fa803c25/source/Interrupt%20List/INT%2021%20DOS%20Function%20Calls/INT%20215D00%20DOS%2031%20internal%20SERVER%20FUNCTION%20CALL.txt

E. C. Masloch on 2026-06-07 09:37:05 +0200 Jun Sun

Fixed in hg 98356c0f2cfc and in hg 5ff9ade920ad both on 2026-04-26. MS-DOS v4.01 user stack functions (33h, 50h, 51h, 62h, 64h) and high functions will return AL=00h CF unchanged now. Functions 25h and 35h are implemented twice, once as user stack functions (see #115) and once as normal dispatcher functions.