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OS/8 programming overview?

commodorejohn

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So I've picked up an SBC6120 kit now that my number finally came up on the waiting list :) Still need to get it assembled, but I'm starting to scheme up a little development project that I'm kinda hoping to have ready for the next VCFW ;) However, OS/8 isn't like DOS where there's a million different introductions to programming for it just floating around on the Internet (or CP/M where it's so bare-bones that the actual official manual is a mere hundred-plus page paperback,) and while I could just sit down and poke through everything Bitsavers has in the way of documentation, I figure I might as well ask around and see if anyone can point me to a basic overview of how the environment is laid out from the programmer's point of view. Is it like bank-switched CP/M where the program mostly or entirely resides in its own little world except for a bit of dispatch code to transfer system calls to the OS residing in another bank? I did see some mention in some of the documentation of a couple pages in high memory (within fields 0-2, IIRC) that are reserved for the OS, but I'm not exactly clear on the details...
 

commodorejohn

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Thanks, but I'm not seeing anything on OS/8 specifically...? That seems to be more of an architectural overview and guide to specific assemblers/compilers. The PDP-8 architecture is amply documented online, thankfully - where I'm having trouble is in trying to find out about the specifics of the operating environment under that OS; granted, I could just go full bare-metal, but I'd like the use of some basic OS facilities at least while developing the initial core program.
 

Chuck(G)

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Yeah, basically OS/8 is a very very simple operating system. Flat file structure, etc. Nothing fancy--but then, you don't expect much from a PDP8, do you?
 

ClassicHasClass

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This makes me want to drag my DECmate II out now that the VR201 is free (since the DEC PRO 380 got a VR241). I'd like floppy software for it though. Is there an easy way to make DECmate compatible floppies on a PC with a 5.25"?
 

Chuck(G)

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I once did a bunch of conversion from DECMATE WPS floppies. Each page of data was split between three sectors, with 6 bit escape codes. It was interesting.
 

commodorejohn

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This makes me want to drag my DECmate II out now that the VR201 is free (since the DEC PRO 380 got a VR241). I'd like floppy software for it though. Is there an easy way to make DECmate compatible floppies on a PC with a 5.25"?
Yeah, there's a DOS program called PUTR that can write RX50 floppies in a normal 5.25" drive. It's in the simh additional-tools kit. I've only ever used it with my 11, but I can't imagine why it wouldn't work with the DECMate as well.
 

Lou - N2MIY

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Yeah, there's a DOS program called PUTR that can write RX50 floppies in a normal 5.25" drive. It's in the simh additional-tools kit. I've only ever used it with my 11, but I can't imagine why it wouldn't work with the DECMate as well.

It won't work because the DECMate II needs the slushware. The best way to make bootable DECMate II floppies are from images and Dave D.'s Imagedisk.

Lou
 

commodorejohn

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Yes, that's a great resource - nicest coverage of the basic architecture/instruction set I've yet found (though it doesn't cover the extended math instructions.) Though, again, lots on the architecture and not so much on the OS environment, but I suppose with a system where often enough things were just run on the bare metal that's hardly surprising.

Now, though, having skimmed through the OS/8 Software Support Manual a bit, I'm both enlightened and a little more confused - it looks like there are system calls to open and close files, but not to read from or write to them!?

(BTW, if anyone is interested in that XWindows panel-interface 8/e emulator he hosts a copy of, I got the source tweaked to build and run on modern Linux. What was with C programmers declaring absolutely everything untyped static in the '80s-'90s? This is like the third old program I've tried to build recently where the compiler chokes on that.)
 
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