Loadrom and memory usage

Door mfeingol

Champion (293)

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21-06-2016, 07:11

I noticed something odd with Loadrom 1.97 the other day...

My configuration: a Philips 8250 with a 512kB memory expansion cartridge.

If I boot into MSX-DOS (1 or 2) from a floppy drive, I can run the Maze of Galious and Aleste roms using Loadrom. It finds 030 pages of RAM, and happily loads all pages of the roms.

But if I boot using Nextor and an SD card (on either an SD-512 or an MFR-SCC+SD), Loadrom finds the exact same number of pages, but it hangs after loading page 4 of the roms.

This is reproducible in openMSX as well.

My guess is that Loadrom is somehow overwriting memory being used by the device driver that's needed for I/O, so it's basically clobbering itself.

Does anyone know of a way to prevent that?

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Van Manuel

Ascended (19053)

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21-06-2016, 21:35

Which loadrom is this? The one of trunks? Is it possible that's a DOS1 application that can't handle the memory mapper stuff that DOS2 does? If so, try with MAP.COM...

Van mfeingol

Champion (293)

afbeelding van mfeingol

21-06-2016, 23:41

Yep, Trunks' Loadrom. It ships with Sofarun. It's actually able to load some megaroms reasonably well, which surprised me.

I can boot to DOS2 from a floppy drive and Loadrom works fine, so I don't think the problem is DOS2-specific. Loadrom also seems to work okay in a Zemmix NEO with an SD card and "native" DOS2. So the problem may actually be with Nextor itself, or something underneath it.

Using map.com causes Loadrom to lock up immediately, even before listing the page count.

Van Louthrax

Prophet (2435)

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22-06-2016, 05:57

It must be using high-TPA addresses, a bit like SofaUnZip before the new optimized version I sent you. Fixing it requires a patch I guess. Maybe you can try to remove some things from your AUTOEXEC.BAT waiting for that ? (I think it worked well with my configuration, but I do not use the LOADROM option too much).

Van mfeingol

Champion (293)

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23-06-2016, 22:08

@Louthrax: there's not much in my autoexec.bat except a few path entries... And the Nextor environment in which it fails has more free TPA memory than the DOS2 environment in which it succeeds.

Does Loadrom work for you with, say, galious.rom?

And do you know if it's still actively being developed?

Van blackmsx

Expert (77)

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27-06-2016, 17:33

I can confirm I can load RC749.rom (Maze of Galious) with SofaRun (it uses Loadrom I belive) from my IDE interface (sunrise clone) with Nextor. My Sony HB-F9S is been upgraded to 512K internally. The memory mapper shows at slot 3.2

Van mfeingol

Champion (293)

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28-06-2016, 04:17

Thanks, blackmsx. That's an interesting data point and I believe I can reproduce it in openMSX.

It's easy to reproduce the Loadrom failures with an emulator MFRSCC+SD in openMSX, and on my own physical machines with an MFRSCC+SD and an SD-512, so the issue may be something with the way the hardware works.

(The former has a flash rom so it doesn't really matter anyway, but the latter doesn't.)

Van blackmsx

Expert (77)

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28-06-2016, 22:34

I did a couple more tests:
Tryed Loadrom with a 4096K mapper cartridge and it doesnt work. It hangs after it displays the memory pages count.
I also tryed it on my 1chipMSX with 2048K mapper and in this case it works perfectly.

Van mfeingol

Champion (293)

afbeelding van mfeingol

29-06-2016, 23:18

That's interesting. Loadrom works fine with 4096kB in Slot 0-3 on a Zemmix NEO.