Developing for MSX-DOS2 and >64kb

pjshumphreys
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Re: Developing for MSX-DOS2 and >64kb

Post by pjshumphreys »

Looking at the msxdos1 situation, there don't seem to be any msx1 machines that came with msxdos1. The first machine to come with msxdos of any kind was the National CF-3300, which was an msx2 machine. I was able to boot msxdos1 on an emulated toshiba hx-10 with and attached panasonic FS-FD1A disk drive though.

I'm starting to think writing a driver to control msx mapper ram directly might be work looking at. Years ago I looked at writing a driver for an Amstrad PCW512 to implement MSX2 mapper-like functionality via the RSX bdos function (60h). It would be cool to have a suite of drivers for different cp/m machines with more than 64kb of ram so that you could write 1 program that can use several 16 kb banks without having to manually control all the different types of hardware. Amstrad CPC machines can be expanded to 512kb I think and there's this for cp/m on the apple II: https://gglabs.us/node/2321
Oh and there's a quite common 512kb ram card for the RC2014 as well.
megatronuk
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Re: Developing for MSX-DOS2 and >64kb

Post by megatronuk »

Yes, actually (the use of) MSX-DOS1 seems to be far more common on =>MSX2 machines than DOS2, and DOS1 appears to have been continued to be used mostly in preference to DOS2 because of the (much) lower memory requirements and lack of requirement for the extension rom.

This would appear to validate the historical curiosity of the profusion of 'MSX-DOS2 compatible' memory mapper utilities (mu.com, msr.com, memman.com, et-al) for MSX-DOS1; most people back in the late 80's probably chose to update their systems with increased memory, but were likely happy enough with the disk facilities of DOS1.

The fact that most systems also only have two cart slots means you also had to be choosy about what exactly you added. I'd guess most 'gamers' probably added a memory mapper and an FM cart, or something along those lines. DOS2 was probably not on their radar as a priority.
megatronuk
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Re: Developing for MSX-DOS2 and >64kb

Post by megatronuk »

It's funny that it only appears to be in later years with the advent of cheap mass-storage carts for the MSX (Sunrise IDE, MegaSCSI, MegaflashromSCC+, etc) that the use of DOS2 (and equivalents including Nextor) seems to have taken off. My guess is that without those, most people would probably still be happy using MSX-DOS1 floppies.
pjshumphreys
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Re: Developing for MSX-DOS2 and >64kb

Post by pjshumphreys »

Am I remembering rightly that msxdos2 adds support for fat16 rather than just fat12 on floppies? If that's true then maybe much of the benefit of msxdos2 is with larger capacity mass storage devices such as ide hard drives or compact flash.
megatronuk
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Re: Developing for MSX-DOS2 and >64kb

Post by megatronuk »

I don't think it got native support for anything other than FAT12 (https://www.msx.org/wiki/MSX-DOS_2), but it has certainly been patched in to the rom for various mass storage devices, such as those above.

Nextor (https://www.msx.org/wiki/Nextor) is a continuation of DOS2, and has specific targets for different types of cart extensions. It has a lot more facilities than the original, floppy-only DOS2.
pjshumphreys
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Re: Developing for MSX-DOS2 and >64kb

Post by pjshumphreys »

msxdos2 definitely had new support for sub directories though. That would make a larger capacity drive more practicable.
megatronuk
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Re: Developing for MSX-DOS2 and >64kb

Post by megatronuk »

Absolutely - if you were stuck with the CPM2/DOS1 style of no sub-directories, it would get very messy rather quickly. You'd probably also run in to the root-directory file entry limit before too long.
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