ag@elgar.UUCP (Keith Gabryelski) (10/22/88)
Distribution has been limited to comp.unix.questions and comp.sys.ibm.pc. Follow ups to comp.sys.ibm.pc. In article <1279@umbc3.UMD.EDU> brian@umbc3.UMD.EDU (Brian Cuthie) writes: >In article <168@ernie.NECAM.COM> koll@ernie.NECAM.COM (Michael Goldman) writes: >>There are some other problems >>with DMA on the PC. One is that DOS is not re-entrant and so you have >>to VERRRY Carefully save the state with any program that uses interrupts >>which is implicit in any reasonable application with DMA. With all the > >Besides, I know what re-entrant instructions are (and besides, >they're "restartable instructions", but that's a different point), >but what the !%^%@ is a re-entrant operating system. For DOS people, re-entrant operating system, does indeed, mean something. DOS was written without any regards for multi-tasking programs. In DOS, the system routines use the same static buffers. This prevents two routines, say a foreground process and a TSR, from doing DOS calls at the same time. There is infact a flag that is set when a DOS call is initiated that should be checked by all TSRs before attempting any DOS call. So, in the contex in which Micahael was talking, the answer to your question... >Can you name one ?? I bet not. ... is Unix. Pax, Keith -- ag@elgar.CTS.COM Keith Gabryelski ...!{ucsd, jack}!elgar!ag