64KB RAM Atmos?

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Brana
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64KB RAM Atmos?

Post by Brana » Mon Dec 03, 2007 8:04 pm

64KB RAM Atmos?


Hello everyone :)

I am Brana (Branislav Gavric) from Zvornik (town in Bosnia and Herzegovina, or former Yugoslavia)

I'm new on this forum, but some of you may remember me from the time of oric[et]lyghtforce.com

I would like to ask you a question that I hope it's a simple one to answer but it was bugging me for a rather long period of time;

In the Euphoric documentation I have found the following text:

* SelectRomWithPB5=No
; Yes,No
(Allows to use an oric with a double-size ROM (32 KB), the active half being selected by the PB5 VIA output.)

Now, if I understood the documentation correctly, it means that I could use Oric Atmos (on the Euphoric emulator) with 64 Kilobytes of memory available, instead of "just" 44Kb, and in order to achieve this is to:

1) Enable the above stated option in the Euphoric.ini file, and
2) to point the Euphoric.ini file to the correct location of the
32 KB ROM file on my hard disk, example:

AtmosRom=roms\Basic11b.rom (32KB file)

Only problem: I do not have an 32 Kilobytes Basic11b.rom file, only the 16 KB one.

My question is:

Have I understood this "procedure" correctly and if I have, then - from where can I download the required 32 KB ROM file?

I have searched THIS forum in detail but I didn't found such a link. I did not have much time to check out all other Web sites regarding Atmos (please forgive me - I do not have Internet access in my home - I have to go down town and use "public" computer(s) and because of that my Internet-spent-time always is "reduced" to some rather-short period :(

I did try to use my existing 16KB Basic11b.rom file that came with the Euphoric.exe but emulator (Atmos) would just "froze" on the startup (not very clever from me, huh?)

Anyway, hope this is a simple question to answer (again - if I understood the Euphoric documentation correctly, if not - could you explain it for me in detail, please?)

For, I do a LOT of programming in Atmos BASIC and most of my programs starts with something like this:

0 GRAB
1 DIM A$(500)
2 DIM S$(500)
3 DIM Q%(500)

and I could use any "extra available peace of memory" :))

Best regards and really glad to see an Oric-based forum finally created - good work Mr. Dbug :)

Brana

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Dbug
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Re: 64KB RAM Atmos?

Post by Dbug » Tue Dec 04, 2007 9:55 pm

Brana wrote:64KB RAM Atmos?
In the Euphoric documentation I have found the following text:

* SelectRomWithPB5=No
; Yes,No
(Allows to use an oric with a double-size ROM (32 KB), the active half being selected by the PB5 VIA output.)

Now, if I understood the documentation correctly, it means that I could use Oric Atmos (on the Euphoric emulator) with 64 Kilobytes of memory available, instead of "just" 44Kb, and in order to achieve this is to:
I have no particular knowlege about this, but I think that if it actually makes it possible to use a 32kb ROM, it just means that you can have either of the following configuration:
- 48K RAM + 16K ROM (First half of a 32K ROM) if ROMDIS=0 and PB5=0
- 48K RAM + 16K ROM (Second half of a 32K ROM) if ROMDIS=0 and PB5=1
- 64K RAM if ROMDIS=1 and PB5=0

The only real way to use the 64K mode is to use a microdisc and some assembly code to swap out the ROM.

From BASIC, the only way to do that is to use some external assembly which will freeze all interruptions, swap out the rom, do whatever exchange of data needs to be done between the BASIC program DATA and the overlay memory, install the ROM again, reenable the interruptions.

It's doable, but you need to have a good knowledge of the way the BASIC data are stored.

I guess a BASIC and 6502 expert programmer could patch the BASIC to make it possible to read/write data directly in overlay memory, but the performances would be probably horrendous.

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