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MASM generates REP CS:MOVSW as: REP CS: MOVSW The Seattle Computer Products 8086 assembler allows the segment override as a discrete opcode. This means that: CS: REP MOVSW is also possible, and in fact used in the SCP Monitor v1.6. The i86 emulator was clearing the override flags when REPE/REPNE, is encountered, which causes the segment override to be lost. Verifying the behavior of a real 80286 processor in an IBM PC/AT (5170) using MS-DOS 6.22 DEBUG shows that both instruction sequences yield the desired segment override.
Open SIMH machine simulator
This is the codebase of SIMH, a framework and collection of computer system simulators.
SIMH was created by Bob Supnik, originally at Digital Equipment Corporation, and extended by contributions of many other people. It is now an open source project, licensed under an MIT open source license (see LICENSE.txt for the specific wording). The project gatekeepers are the members of the SIMH Steering Group. We welcome and encourage contributions from all. Contributions will be covered by the project license.
The Open SIMH code base was taken from a code base maintained by Mark Pizzolato as of 12 May 2022. From that point onward there is no connection between that source and the Open SIMH code base. A detailed listing of features as of that point may be found in SIMH-V4-status.
PLEASE NOTE
Do not contribute material taken from github.com/simh/simh unless you are the author of the material in question.