Jump to content
Sign in to follow this  
mnielsenau

Oasis Pensive Abacutors (OPA) ROMS in Mame?

Recommended Posts

Hey guys,

 

Back in the day I purchased a copy of PC99 from CADD Industries and had played around with it extensively back then. One of the things I really liked was being able to use the OPA ROM/GROM set in PC99 as it had that great startup screen to do disk catalogs as well as start the modules. 

 

As I said I have a legitimate copy of the ROM/GROMS and wonder is there any way of converting them to work in MAME? I have played around and successfully split the ROM file into HIGH byte and LOW byte format which MAME requires and called them all the right names in the .ZIP archive. I know that the GROMS are 8K instead of the usual 6K and MAME complains about the length discrepancy and this may be the stumbling block right there.... :)

 

If someone knows how to convert them and using them in MAME it would be appreciated.

 

Cheers,

 

Mark. 

  • Like 1

Share this post


Link to post
Share on other sites

If I understand right, the ROMs/GROMs are part of the PC99 emulator and were never used in the real hardware, so PC99 allowed for "GROMs" with 8K? (There are no real GROMs with that capacity.)

 

No, this won't work in MAME, sorry. You may replace the ROM and GROM contents (and get complaints from the emulator that the checksums are wrong), but they must fit the original sizes. I actually emulated the GROM circuits with their three 2K banks and the fourth as a combination of two other banks, so it is not just a simple setting to allow for 8K.

Share this post


Link to post
Share on other sites
58 minutes ago, mizapf said:

If I understand right, the ROMs/GROMs are part of the PC99 emulator and were never used in the real hardware, so PC99 allowed for "GROMs" with 8K? (There are no real GROMs with that capacity.)

 

No, this won't work in MAME, sorry. You may replace the ROM and GROM contents (and get complaints from the emulator that the checksums are wrong), but they must fit the original sizes. I actually emulated the GROM circuits with their three 2K banks and the fourth as a combination of two other banks, so it is not just a simple setting to allow for 8K.

Michael,

 

I may be mistaken, but I thought with the GramKracker, the hardware was designed with 8K memory banks.  I thought the GKUTILS package added capability to the Grom/Gram in the extra 2K.

 

I could be wrong as I was no hardware expert, but I thought I remembered going in and doing some gram editing back in the day in the upper 2K of the individual banks.

 

Beery

 

  • Like 1

Share this post


Link to post
Share on other sites
39 minutes ago, 9640News said:

Michael,

 

I may be mistaken, but I thought with the GramKracker, the hardware was designed with 8K memory banks.  I thought the GKUTILS package added capability to the Grom/Gram in the extra 2K.

 

I could be wrong as I was no hardware expert, but I thought I remembered going in and doing some gram editing back in the day in the upper 2K of the individual banks.

 

Beery

 

I know that the Gramulator could use the extra space but not sure about GramKracker. The SNUG HSGPL may also allow the extra space. 

 

I checked the ROMS and they are unchanged from the console ROMS so its only the GROMS that I need to load. 

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, mizapf said:

If I understand right, the ROMs/GROMs are part of the PC99 emulator and were never used in the real hardware, so PC99 allowed for "GROMs" with 8K? (There are no real GROMs with that capacity.)

 

No, this won't work in MAME, sorry. You may replace the ROM and GROM contents (and get complaints from the emulator that the checksums are wrong), but they must fit the original sizes. I actually emulated the GROM circuits with their three 2K banks and the fourth as a combination of two other banks, so it is not just a simple setting to allow for 8K.

Hi Michael 

 

Thanks for your response. Yes the ROMS/GROMS were distributed with PC99 but I think they were also used in the Zeno board as well from memory. 

 

Based on how they are loaded by MAME then I think the standard way won't work but as Beery mentioned some sort of emulated GRAM device might work. 

 

I will add the GramKracker header to the GROMS and try it with the HSGPL under MAME and see how it goes over the weekend. 

 

Will let you know how it goes. 

 

Cheers. 

 

Mark. 

  • Like 1

Share this post


Link to post
Share on other sites

Yes, GRAMKracker could be a viable way (as well as HSGPL). It is just not possible to replace the console GROM dump files with 8K dumps.

Share this post


Link to post
Share on other sites

IIRC, the OPA GROM changes for the console were also released as a physical daughter board to replace the console GROMs. That mod would have been the S.O.B. (Son of a Board). The PAL chips were programmed to support using the entire 8K space, based on a conversation I had with Gary Bowser back when I was researching possibilities for developing a GROM-capable cartridge. I ended up going in another direction, as Tursi had a much more elegant single-chip solution using the ATMEL Atmega1284P to both emulate GROMs and store the code.

 

One other note on the OPA GROMs: they corrected the issues TI BASIC (console BASIC) had with 80-column devices using V9938 or V9958 chips.

  • Like 1

Share this post


Link to post
Share on other sites

Such a SOB could be a future configuration option in MAME (similar to the internal 32K mem).

 

(Edit: I'll finish SCSI first.)

  • Like 3

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...