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Atmos ROM

Posted: Wed Oct 03, 2012 9:31 am
by Igotafro
My Oric Atmos got the bugged tape loading version of the ROM (PEEK(#E4B6) gives 162).
So I burned a new ROM (the PEEK(#E4B6) =142 version) and then it worked fine.
But then I noticed that my MicroDisc doesn't work with that version.
I thought my MicroDisc was broken, had a real scare, until I swapped back to the old ROM.
Anyone know anything about this? I don't want to have to install a TWINROM.
Maybe I can hack my own version.

Re: Atmos ROM

Posted: Wed Oct 03, 2012 11:29 am
by Silicebit.
Have you used an EPROM? The original ROM has one /OE1 line at pin 27, and in the 27128/27C128 EPROM pin 27 is /PGM.

EDIT: Pin 27 is conected as /ROMDIS signal on expansion bus.

Re: Atmos ROM

Posted: Wed Oct 03, 2012 1:47 pm
by Igotafro
Ah, that's why. Too bad that the eprom got /OE at pin 22 instead, but I guess I could just lift the PGM and OE pins out of the socket and solder a wire to fix it.

Re: Atmos ROM

Posted: Wed Oct 03, 2012 4:16 pm
by Chema
Just for the records, I also have a first version of the Atmos ROM with the loading bug. It is indeed a pain, but beware because the newer versions simply disabled the error checking completely, so it may seem you correctly loaded something and discover later on that you didn't.

Nothing worse than a game hanging when you are about to get your highscore, or loading/editting/saving your work to notice later that you screwed everything up!

Re: Atmos ROM

Posted: Wed Oct 03, 2012 7:26 pm
by Silicebit.
Igotafro wrote:Ah, that's why. Too bad that the eprom got /OE at pin 22 instead, but I guess I could just lift the PGM and OE pins out of the socket and solder a wire to fix it.
I have one of my Atmoses with a 27C128 EPROM burnt with Pascal Leclerc´s 1.21 version, and I think that is not as easy as you says. /OE at pin 22 is used by Phi2, through the inverter IC21, to enable data output when ROM is addressed.

I think we must use a two inputs NAND gate to accomplish the trick. Something as this:
oric1-2s.gif
oric1-2s.gif (20.76 KiB) Viewed 12772 times
I agree with Chema, I prefer the ultra-efficient loading routine to loading programs with mistakes.

Re: Atmos ROM

Posted: Thu Oct 04, 2012 12:48 am
by Igotafro
Ah, then I won't bother, though I'd like all games on my Microdisc then. Can I request Microdisc versions of Impossible Mission, Skool Daze and Stormlord? :)

Re: Atmos ROM

Posted: Thu Oct 04, 2012 8:20 am
by Dbug
Igotafro wrote:Ah, then I won't bother, though I'd like all games on my Microdisc then. Can I request Microdisc versions of Impossible Mission, Skool Daze and Stormlord? :)
Just try Tap2Dsk?

Re: Atmos ROM

Posted: Thu Oct 04, 2012 2:03 pm
by Igotafro
Damn, you learn something every day, playing Stormlord now! Thanks!

Re: Atmos ROM

Posted: Thu Oct 04, 2012 2:50 pm
by Igotafro
Hm, Impossible Mission won't start and tap2dsk hangs on SkoolDaze.

Re: Atmos ROM

Posted: Thu Oct 04, 2012 8:25 pm
by Dbug
Igotafro wrote:Hm, Impossible Mission won't start and tap2dsk hangs on SkoolDaze.
For impossible mission, it's because it overlaps the page 4 variables, so just loading it crashes the system.
Try the one I attached :)

Re: Atmos ROM

Posted: Thu Oct 04, 2012 9:10 pm
by Chema
And the version of tap2dsk included in OSDK 0.19 works with Skool Daze (not sure why the one with 0.17 didn't).

However Skool Daze is not working when loaded from disk directly. It also messes with page 4 and apparently SEDORIC sets the IRQ vector to page 4. It should be easy to fix, just setting the IRQ to the one the game uses before messing with page 4, but (and that is the good news) there is a workaround:

Simply issue a !Quit and then !Skooldaze. It works :)

I guess it should do also for impossible mission.

Re: Atmos ROM

Posted: Fri Oct 05, 2012 3:38 pm
by Igotafro
Thanks, but I'm having all sorts of trouble getting this to work. I'm using the tools from the newest OSDK.
So, I'm trying to convert im-small.tap to im-small.dsk using: tap2dsk im-small.tap im-small.dsk
This works on my Win XP-machine, but hangs on Win 95.
Then I used old2mfm on im-small.dsk (in WinXP), I'm supposed to do that right?
Ok, so now I got my im-small.dsk, but it just fails to write with writedsk, on both WinXP and Win95.
I tried again with my downloaded space1999-en.dsk on Win95 and it works fine with writedsk.

Re: Atmos ROM

Posted: Sat Sep 13, 2014 2:25 pm
by Silicebit.
Dbug wrote:
Igotafro wrote:Hm, Impossible Mission won't start and tap2dsk hangs on SkoolDaze.
For impossible mission, it's because it overlaps the page 4 variables, so just loading it crashes the system.
Try the one I attached :)
Which are the differences between IM10 and im-small?

Re: Atmos ROM

Posted: Sat Sep 13, 2014 3:56 pm
by Dbug
It's the version I hacked from Jonathan's source code: I moved all the buffers at the start of the program, and they are cleared *after* the program start.
So basically it will erase what is in page 4, like the previous version, but at least it allows the loading because it loads higher in memory.

I also made a smaller version that uses filepack, so the program is roughly half the size of the original game, which makes it load twice as fast on tape.

Re: Atmos ROM

Posted: Mon Sep 15, 2014 7:08 pm
by Silicebit.
Thank you very much for the explanation, Mike. I've transferred the game to real disk, and i'm enjoying very much playing it on my real Atmos. :-)