On Mon, 1 Sep 2025 11:47:49 -0500, Paul Edwards <[email protected]> wrote:
>Basically with everything written in terms of C90, >everything is everything. Pretty much any API >you throw at it - even the MVS API (SVC 120 to >get memory etc), I convert it back to a call to >malloc() and we're back to where we started - >anything, anywhere. I haven't done that work yet >though. Other than proof of concept that I can >override an SVC in userspace with cooperative >programming (read: just PDPCLIB). Oh - and so that means you'll have an ASCII version of (a mini) MVS too. Potentially MVS hasn't been emphatically proven conceptually. Specifically I need to show that from C I can have an assembler callback function for use in a RDJFCB exit or whatever that will get me back to C code, and in the right AMODE, and I can control it from C code. But it's a pretty sure bet that it's a "simple matter of programming". There's no magical feature that can't be replicated with a bit of supporting assembler. But I haven't looked into all the internals of mvssupa.asm - maybe every single register is accounted for and I can't possibly do something from C. But I don't believe there are any missing concepts left for me to complete what I want to do. Note that the technique for overriding an SVC (which I thought was impossible), only came about when I was trying to do the same thing on the Atari - I thought it was impossible to override a 68000 trap from usermode. So I could do the Atari, which had a C interface to the OS, but Atari was impossible. No. It wasn't impossible. And that opened up MVS SVCs. It was someone in the Atari forum who pointed out how I could do it within my listed constraints - I didn't invent it myself. And the whole PDOS-generic design was invented in an Amiga forum. And a lot was achieved trying to force the XT to work too. And MVS was a big influence the whole time too. And nothing was done in a vacuum. BFN. Paul. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
