First post, by bjt
- Rank
- Oldbie
Cross-posting from GitHub for visibility.
https://github.com/bjt42/softmpu/issues/31#is … ment-1873335328
My understanding is that the motivation behind adding HDMPI32i port trapping support to SoftMPU would be to support protected-mo […]
My understanding is that the motivation behind adding HDMPI32i port trapping support to SoftMPU would be to support protected-mode games. To my knowledge, there aren't any protected mode games that require SoftMPU's 'Intelligent Mode' emulation. Therefore, I believe the use-case is more specifically to support MIDI redirection (serial port or otherwise) for protected-mode game, as a way of achieving MIDI output on machines without hardware MIDI ports.
While SoftMPU does support MIDI redirection, it's very much an adjunct to the core 'Intelligent Mode' functionality. Furthermore, MIDI redirection is a relatively straightforward case of capturing output to the MPU I/O ports and outputting it instead to the serial port.
SoftMPU also does some fairly hairy things to support 'Intelligent Mode' emulation (for example, reprogramming the RTC, writing to the GDT from within the port trap handler) that while well-tolerated by EMM386/QEMM/possibly JEMM, and the smaller set of older real-mode games requiring 'Intelligent Mode', are likely to reduce compatibility in the general sense. For this reason I regard SoftMPU as a 'load only when needed' proposition.
To summarise, if the specific requirement is for MIDI redirection for PM games, I feel there is a strong case for implementing that in a new, more compatible TSR, likely leveraging HDPMI32i (from what I have read about it).
