Euphoric won't load ROM file

Comments, problems, suggestions about Oric emulators (Euphoric, Mess, Amoric, etc...) it's the right place to ask. And don't hesitate to give your tips and tricks that help using these emulations in the best possible way on your favorite operating system.
Post Reply
Yicker
Pilot Officer
Posts: 86
Joined: Thu Jan 26, 2006 11:27 pm
Location: St. Helens, Merseyside, UK

Euphoric won't load ROM file

Post by Yicker » Fri Apr 25, 2008 1:42 pm

Hi,

I've been playing around with the Atmos ROM file (BASIC11b.rom) to test some changes to some of the commands. However when I try and run up Euphoric with the new ROM file it just displays a screen of vertical grey stripes and doesn't get to the Oric welcome screen. :-(

Does Euphoric do any checks on the ROM file when it loads it up?

Cheers
Scott

User avatar
Chema
Game master
Posts: 2078
Joined: Tue Jan 17, 2006 10:55 am
Location: Gijón, SPAIN
Contact:

Re: Euphoric won't load ROM file

Post by Chema » Fri Apr 25, 2008 3:58 pm

Hi,

You will probably have to wait until someone with deep knowledge answers, but I guess it does not perform any checking. Else it should at least exit with an error...

The most probable thing is that your modified rom is not booting the Oric properly... Those stripes you see... are they on the Oric screen? Because different roms create different patterns when booting...

IIRC whenever a memory module is broken or something is going wrong in the bootup process, the screen hangs with a funny pattern on screen...

But, as I said, these are just guesses...

User avatar
Symoon
Archivist
Posts: 1169
Joined: Sat Jan 14, 2006 12:44 am
Location: Paris, France
Contact:

Post by Symoon » Fri Apr 25, 2008 11:46 pm

From a discussion I had with Fabrice years ago, I recall the screen you see when booting is the memory. It depends on the chips used, or something like that.

In Euphoric, the boot screen is simulated, and you can choose in the INI file between 3 different boot screens. So there's no link with the ROM I guess - especially not on Euphoric anyway.
Last edited by Symoon on Sat Apr 26, 2008 8:51 am, edited 1 time in total.

Yicker
Pilot Officer
Posts: 86
Joined: Thu Jan 26, 2006 11:27 pm
Location: St. Helens, Merseyside, UK

Post by Yicker » Sat Apr 26, 2008 1:17 am

Hi guys,

Thanks for the prompt replies.

I've been debugging the ROM file and found that during startup it fills all memory locations with hex value 55, including the screen memory.

The binary value of #55 is 1010101 which explains the stripes that I can see. It should then display the 'ORIC EXTENDED BASIC'... message which it currently isn't so I must have accidently changed something in the ROM that is preventing the startup screen from showing although at the moment I'm not sure what that is.

More debugging required. :-)

Cheers
Scott

User avatar
Symoon
Archivist
Posts: 1169
Joined: Sat Jan 14, 2006 12:44 am
Location: Paris, France
Contact:

Post by Symoon » Sat Apr 26, 2008 8:51 am

Oh, I think I was mistaken. I thought you were talking about large stripes that can be seen at the very beginning of Euphoric running, but you were actually talking about the 1-pixel-large stripes that breifly appear when the Oric switches from the boot screen to the welcome message, isn't it?

If so, I suspect something wrong with the ROM, too - but I'm no expert.

Yicker
Pilot Officer
Posts: 86
Joined: Thu Jan 26, 2006 11:27 pm
Location: St. Helens, Merseyside, UK

Post by Yicker » Sat Apr 26, 2008 12:51 pm

Sorry Symoon, i didn't give a very good explanation.

I do get the big white lines/blocks that appear at the very beginning.

Hopefully I'll get sometime over the weekend to debug the ROM and track down what's going on.

Cheers
Scott

highwayman
Flying Officer
Posts: 148
Joined: Fri Oct 12, 2007 8:08 pm

Post by highwayman » Sat Apr 26, 2008 10:03 pm

check for jumps (jsr/jmp) into your modified routines,

it may be jumping into a routine you changed but *not* jumping into the start but the middle of one.

i'v done that - dirty but saves writing the same code again.

User avatar
Dbug
Site Admin
Posts: 2387
Joined: Fri Jan 06, 2006 10:00 pm
Location: Oslo, Norway
Contact:

Post by Dbug » Sun Apr 27, 2008 9:49 am

you can also put a breakpoint at the start of the rom (like a jmp on itself), and trace the code using the debugger. Or when it crashes, just press F11 to enter the debugger and check where you are in the code, may help finding what's wrong based on the crash adress.

Yicker
Pilot Officer
Posts: 86
Joined: Thu Jan 26, 2006 11:27 pm
Location: St. Helens, Merseyside, UK

Post by Yicker » Mon Apr 28, 2008 12:25 am

Hi guys,

I've finally solved the problem with the ROM file. :-)

Turns out that the assembler I was using was at fault. The last byte of the ROM should have been #02 but the assembler wasn't writing the last byte so it had a default value of #FF instead.

Unfortunately the last two bytes in the ROM are the IRQ vector address (#0244) so this was being set to #FF44.

I amended the assembler code to write all the bytes and the ROM file now works okay.

Thanks to everyone who took the time to response to my request :-)

Cheers
Scott

User avatar
Dbug
Site Admin
Posts: 2387
Joined: Fri Jan 06, 2006 10:00 pm
Location: Oslo, Norway
Contact:

Post by Dbug » Mon Apr 28, 2008 8:57 pm

Is it possible to know which assembler you are using ?
I guess people would be interested to know about the bug if they happen to use the same :)

Yicker
Pilot Officer
Posts: 86
Joined: Thu Jan 26, 2006 11:27 pm
Location: St. Helens, Merseyside, UK

Post by Yicker » Wed Jun 15, 2011 5:26 pm

Hi,

Just been looking through all my old posts and I realised that I hadn't replied to your message Dbug :oops:

I know it's taken a while to reply :? but in answer to your question, the assembler I was using was one that I had written myself using C# so don't need to worry about anyone else coming across the bug. :)


Cheers

User avatar
Dbug
Site Admin
Posts: 2387
Joined: Fri Jan 06, 2006 10:00 pm
Location: Oslo, Norway
Contact:

Post by Dbug » Wed Jun 15, 2011 6:08 pm

Not a problem, thanks for explaining :)

Post Reply

Who is online

Users browsing this forum: No registered users and 8 guests