3D Fongus with Erebus : does not load

Want to talks about games you like, would like to see developed on the Oric, it's here.
User avatar
Dbug
Site Admin
Posts: 4444
Joined: Fri Jan 06, 2006 10:00 pm
Location: Oslo, Norway
Contact:

Re: 3D Fongus with Erebus : does not load

Post by Dbug »

Does your two Oric show the same patterns on screen when booted? If not, it could simply be that The Ultra does not properly initialize some variables which by default are cleared on some versions of the Oric but not on other.
User avatar
Chema
Game master
Posts: 3014
Joined: Tue Jan 17, 2006 10:55 am
Location: Gijón, SPAIN
Contact:

Re: 3D Fongus with Erebus : does not load

Post by Chema »

Dbug is right. The Oric ROM initializes normal RAM, but not page 0. I am not sure if due to different models of RAM chips or what, some Orics seem to start with different values in page 0.
User avatar
mikeb
Flight Lieutenant
Posts: 282
Joined: Wed Sep 05, 2018 8:03 pm
Location: West Midlands, UK
Contact:

Re: 3D Fongus with Erebus : does not load

Post by mikeb »

Interesting point you raise on incomplete RAM testing -- I just went to check my Adv. User Guide ROM disassembly -- you're right.

Worse: It's not just page 0 that is untested.

It appears a 16bit pointer at #0C/#0D is used to probe the "current" location, and is set to #OC=#FF (1.1 ROM at #FA22) and #0D=#03 (at #FA3A).

The next instruction is inside the test loop, which increments the pointer. So RAM is only tested from #0400 upward to end of memory (set by pointer in #0E,#0F) which terminates at #C000 or #4000 (for 48k or 16k computer).

This means the first 4 pages of memory go untested, as does "shadow" memory.

Unless you do a non-destructive memory test, it's hard to test page 0 when you're already using it for pointers. Same applies for page 1 (stack) which is already in use by this point. Page 3 is a mystery, as all sorts of hardware overlays that (at very least, the VIA chip), so testing that is impossible, as is the shadow RAM, inaccessible to a lone Oric with no hardware assistance.

Tested memory is always left with 0x55 ("U"), but the value in un-initialized memory is not reliable, because although if the DRAM chips are assumed to be all discharged, that doesn't guarantee all 0's or all 1's -- simply because the internal construction of a DRAM chip almost always involves some bits being stored as true logic, others as inverted logic. This is at the whim of the designer of the chip.

Always initialize your variables :)
User avatar
kenneth
Squad Leader
Posts: 515
Joined: Fri Nov 26, 2010 9:11 pm
Location: France PdD
Contact:

Re: 3D Fongus with Erebus : does not load

Post by kenneth »

That's why some values stored at page 0,1,2 are always there even if the selfdestruction code is used (CALL#F88F)
User avatar
Symoon
Archivist
Posts: 2307
Joined: Sat Jan 14, 2006 12:44 am
Location: Paris, France

Re: 3D Fongus with Erebus : does not load

Post by Symoon »

There was also the case with Asteroids from Arctic Computing, which worked on some Oric-1, and not others.
Apparently due to some bad PSG programming... And remember how Twilighte's samples worked on some Orics and not others.
User avatar
dizzy33
Officer Cadet
Posts: 37
Joined: Sun May 31, 2020 10:05 am

Re: 3D Fongus with Erebus : does not load

Post by dizzy33 »

Thanks a lot to all of you, I will check the boot patterns. But there is something I don't understand : when you power off a computer, the RAM content disappear, isn't it ?
User avatar
Chema
Game master
Posts: 3014
Joined: Tue Jan 17, 2006 10:55 am
Location: Gijón, SPAIN
Contact:

Re: 3D Fongus with Erebus : does not load

Post by Chema »

Another thing I experienced is some Twilighte keyboard reading routines not working on my Oric, at least those in Zip&Zap, if I remember correctly. Some keys do not respond, other respond quite randomly (not always detected, and/or detecting different values from the actual key pressed).
dizzy33 wrote: Mon Jun 08, 2020 11:37 pm Thanks a lot to all of you, I will check the boot patterns. But there is something I don't understand : when you power off a computer, the RAM content disappear, isn't it ?
Yes, but it is what Mike said a couple of posts back: the contents are not 0s or 1s... or not always
mikeb wrote: Mon Jun 08, 2020 6:12 pm [...] although if the DRAM chips are assumed to be all discharged, that doesn't guarantee all 0's or all 1's -- simply because the internal construction of a DRAM chip almost always involves some bits being stored as true logic, others as inverted logic. This is at the whim of the designer of the chip.
That means that you cannot guarantee a given value at an address in zero page. If you store a flag in #0000, for instance, meaning 0 = keyboard, 1 = joystick and you do not initialise it, only change its value when the user selects joystick/keyboard control from the menu, it may start with keyboard control on most Orics, but with joystick in other machines...
User avatar
mikeb
Flight Lieutenant
Posts: 282
Joined: Wed Sep 05, 2018 8:03 pm
Location: West Midlands, UK
Contact:

Re: 3D Fongus with Erebus : does not load

Post by mikeb »

dizzy33 wrote: Mon Jun 08, 2020 11:37 pm when you power off a computer, the RAM content disappear, isn't it ?
Assuming a complete power down, and all charge drained away from the DRAM chips, the raw transistor/capacitor cells will all be discharged (same state), yes.

Whether these are interpreted as 1's or 0's is down to the chip designers. You'd need to stare at the data sheet for a typical 4164 chip to see mention of this (and other delights such as row and column address scrambling!)

When you write a zero, and get a zero back (or a 1 and get a 1 back) then as far as you're concerned, from outside the chip, everything is fine.

Internally, the chip may store some of your logic inverted on the way in, and then again on the way out. This cancels out. You don't notice :)

The only time you notice it is when the chip is powered on, (all cells same state). Some bits are inverted on reading them back, and it contains an apparent pre-loaded pattern of 1's and 0's. This pattern is not 100% reliable, and very much depends on the chip manufacturer.

Below: From a Hyundai 4164 datasheet, shows that half of the data stored (rows 0 to 127) are stored as straight logic, and (128 to 255) are stored as inverted logic
Attachments
1.png
1.png (15.32 KiB) Viewed 5505 times
User avatar
kenneth
Squad Leader
Posts: 515
Joined: Fri Nov 26, 2010 9:11 pm
Location: France PdD
Contact:

Re: 3D Fongus with Erebus : does not load

Post by kenneth »

Chema wrote: Tue Jun 09, 2020 9:48 am Another thing I experienced is some Twilighte keyboard reading routines not working on my Oric, at least those in Zip&Zap, if I remember correctly. Some keys do not respond, other respond quite randomly (not always detected, and/or detecting different values from the actual key pressed).
When the keyboard is browsed directly a delay is required between the writing of the i/o register and reading the value, it is about the analogic device on the keyboard pcb wich is slower than the processor timing.
User avatar
dizzy33
Officer Cadet
Posts: 37
Joined: Sun May 31, 2020 10:05 am

Re: 3D Fongus with Erebus : does not load

Post by dizzy33 »

Sorry guys, I met another game loading problem ...
This time, this is with "Harrier Attack". I tried 5 different releases :

https://www.oric.org/software/harrier_attack-52.html
on this site I tried both Oric-1 and Atmos releases, but when I load the game , for the Atmos version I see the Harrier Attack screen with "Loading" and "Please wait" on top of the screen. For the Oric-1 version, same thing but no "Loading", just "Please wait". Of course, nothing happens, even after having waited for more than 15 minutes ...

https://www.planetemu.net/rom/tangerine ... software-2
the release from this site does the same thing than the Atmos version of the previous site.

http://www.gametronik.com/site/fiche/or ... 520Attack/
the release from this site does the same thing than the previous site.

http://www.skarstad.net/oric/archive.html
Same issue here.

Is it working for you with an Erebus ?
User avatar
Symoon
Archivist
Posts: 2307
Joined: Sat Jan 14, 2006 12:44 am
Location: Paris, France

Re: 3D Fongus with Erebus : does not load

Post by Symoon »

Maybe try this one?
viewtopic.php?f=22&t=1957&hilit=harrier&start=15#p19580

I can't recall exactly but I think Harrier Attack might have some code playing with loading routines… Quite hazy memory though, I may be wrong.
User avatar
dizzy33
Officer Cadet
Posts: 37
Joined: Sun May 31, 2020 10:05 am

Re: 3D Fongus with Erebus : does not load

Post by dizzy33 »

Thanks a lot for this link, unfortunatly I get the same result : the game freezes on the "loading" screen.
User avatar
kenneth
Squad Leader
Posts: 515
Joined: Fri Nov 26, 2010 9:11 pm
Location: France PdD
Contact:

Re: 3D Fongus with Erebus : does not load

Post by kenneth »

The zero page is deleted in the first block of the game, I put two NOP, try this :wink:
Attachments
HARRIERm.TAP
(11.45 KiB) Downloaded 341 times
User avatar
dizzy33
Officer Cadet
Posts: 37
Joined: Sun May 31, 2020 10:05 am

Re: 3D Fongus with Erebus : does not load

Post by dizzy33 »

Thanks a million Kenneth, once again, you modified a game and now it works fine ! You're great !
User avatar
jbperin
Flight Lieutenant
Posts: 480
Joined: Wed Nov 06, 2019 11:00 am
Location: Valence, France

Re: 3D Fongus with Erebus : does not load

Post by jbperin »

kenneth wrote: Sat Jun 13, 2020 10:56 pm I put two NOP,
That's chirurgical strike .. what a sense of efficiency .. congrats
Post Reply