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Flash ROM 99 and Final GROM 99 Repository


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#1 atrax27407 ONLINE  

atrax27407

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Posted Wed Sep 27, 2017 2:54 PM

I don't have either one of these devices so I can't test the files for myself. I have noticed that a number of the files in the repository are 32K in length. This is true even though the actual substance of the file is only 8k (ex.TAFARA) in length. When examined with a sector editor, the majority of the 32K file appears to be filled with surplusage and extraneous code (i.e., "Made with Classic 99") which is usually imbedded in file a couple of dozen times. Do these files actually run on either of these devices? It seems a terrible waste of space to have a file bloated to several times its correct size. Is there a requirement that the files be padded out to 32K? Or is some cases 64K?



#2 Lee Stewart OFFLINE  

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Posted Wed Sep 27, 2017 3:19 PM

The FlashROM99 can only run 32KiB ROMs.  There is no provision for smaller (or larger, for that matter) ROMS.  I believe there needs to be code in all banks (or at least 0 and 3) to branch to the startup bank.  The easiest way to do this is to duplicate smaller ROMs to fill the 32 KiB space.  This presumes, of course, that ROM sizes are 8 KiB, 16 KiB or 32 KiB.  If it is possible to have a 24 KiB ROM, I think the last bank would need explicit startup code.

 

...lee



#3 atrax27407 ONLINE  

atrax27407

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Posted Wed Sep 27, 2017 4:04 PM

I guess that means that all of the files that are NOT 32K  in length are Final GROM files. 



#4 jedimatt42 OFFLINE  

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Posted Wed Sep 27, 2017 5:13 PM

I don't have either one of these devices so I can't test the files for myself. I have noticed that a number of the files in the repository are 32K in length. This is true even though the actual substance of the file is only 8k (ex.TAFARA) in length. When examined with a sector editor, the majority of the 32K file appears to be filled with surplusage and extraneous code (i.e., "Made with Classic 99") which is usually imbedded in file a couple of dozen times. Do these files actually run on either of these devices? It seems a terrible waste of space to have a file bloated to several times its correct size. Is there a requirement that the files be padded out to 32K? Or is some cases 64K?


The files that are full of 'Made with Classic 99' are cartridges that are reloading memory images, usually into expansion memory. For lazyness purposes, often all of the upper expansion ram is captured, 24k, and then the cart loader code goes on the front and spills things into a 4th cartridge bank.

I guess that means that all of the files that are NOT 32K  in length are Final GROM files. 


The repository on whtech /Cartridges/FlashROM99/Classic_Carts.zip is full of 16k and 8k carts that are functional on the FlashROM99. So "NOT 32K" doesn't make a 100% sound discriminator. I'm failing to find a reference to it, but I thought Ralph said that FlashROM99 will fill its 32k of SRAM with repetition of 8k or 16k rom images.

-M@

#5 ralphb OFFLINE  

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Posted Wed Oct 11, 2017 4:58 AM

The repository on whtech /Cartridges/FlashROM99/Classic_Carts.zip is full of 16k and 8k carts that are functional on the FlashROM99. So "NOT 32K" doesn't make a 100% sound discriminator. I'm failing to find a reference to it, but I thought Ralph said that FlashROM99 will fill its 32k of SRAM with repetition of 8k or 16k rom images.

 

That is correct.  You can use 1B to 32KB images on the FlashROM, and it will mirror the code into unused banks.  This is required for bank switching.

 

A two-bank image might use all kinds of switch addresses, as only the lowest bit is honored.  But the FlashROM looks at two bits (for four banks), so the two-bank image on the FlashROM might accidentally switch to non-existing banks 2 or 3.  By mirroring code, banks 0/1 are identical to 2/3, so switching doesn't break the program.

 

I wished that images for FlashROM 99 and FinalGROM 99 wouldn't be mixed in the same thread.  But as a rule of thumb, images at most 32K in size and not split into C, D, G and not ending with G are FlashROM 99 files.  The FinalGROM 99 can run all FlashROM 99 images, but may require renaming.






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