Mega-Cart hacking and writing the NvRAM...

tlr · Post by **tlr** » Fri Jul 31, 2009 7:50 am

When I got the Mega-Cart and read about the NvRAM I decided it could be very useful for small developer tool kits.
The only problem was that all of the NvRAM was supposedly used by the menu system and would therefore interfere with normal operations.
After quite a bit of reverse-engineering I found that it was possible to use the NvRAM overlapping the control registers ($9c80-$9fff).

Here is a collection of a NvRAM writing utility and some technical information:
mega-tools-20090731.tar.gz

As a side effect of all this I got enough information to implement emulation of the Mega-Cart hardware in VICE. Available as of development version v2.1.15.

Note: Only write the NvRAM if you know what you are doing as you can easily corrupt your prefs if you write the wrong locations.

nbla000 · Post by **nbla000** » Fri Jul 31, 2009 8:38 am

tlr wrote:Here is a collection of a NvRAM writing utility...

Hey, My compliment to your brillant research work and for your excellent programming abilities.

I've tested your Mega-inject tool for my next SJLoad patch for JiffyDos and uIEC/SD2IEC drives and it works has expected, you have "recycled" the Mega-Cart graphics by keeping the same look and feel of the menu, very great job.

As said, be careful, this programs must be used only if you know what you are doing, may be doungerous for your Mega-Cart if used improperly.

As a side effect of all this I got enough information to implement emulation of the Mega-Cart hardware in VICE. Available as of development version v2.1.15.

Wow, are you a Vice developer ?

It will be nice for users to test the Mega-Cart before to buy, this is a very big thing !!!

Again my compliments for your work, do you work for CIA or something similar ?

Pedro Lambrini · Post by **Pedro Lambrini** » Fri Jul 31, 2009 10:57 am

Wow! A while back I asked if it was possible to emulate the Mega-Cart and the answer seemed to be a no. It just shows that give a hacker/coder enough time and they can do anything! Well done.

PS: Is there going to be a public build of Vice available with this anytime soon?

Diddl · Post by **Diddl** » Fri Jul 31, 2009 11:56 am

@tlr

I would like to see another cartridge emulation in VICE also.

We are shortly bevore releasing our final expansion v3.1: click

I could give you all information needed for this emulation of FE3.1. It would be highly appreciated to have such a emulation in VICE, but I can't so this job.

nbla000 · Post by **nbla000** » Sat Aug 01, 2009 2:42 am

hey tlr a lot of work for you in the next months

tlr · Post by **tlr** » Sat Aug 01, 2009 3:09 am

Thanks for all the compliments!

Yes, I'm a VICE developer. The hard part was to rewrite the cartridge system to be modular like on the c64 emulation.
Adding another cart should be relatively straight forward. Wait and see.

Now back to the NvRAM and other Mega-Cart discussions...

Diddl · Post by **Diddl** » Sun Aug 02, 2009 9:17 am

@TLR
Many thanks for emulation of MegaCart and FE3 in VICE!

I'm deep impressed!! It works perfectly! It is wonderful, nearly like christmas!

Lozza · Post by **Lozza** » Mon Aug 03, 2009 2:03 am

it works ?

ok i'd love to have a squizz..

where to get this beta vice ?

and where for images of the 2 carts !?

Diddl · Post by **Diddl** » Mon Aug 03, 2009 5:12 am

>where to get this beta vice ?
you have to compile it yourself

>and where for images of the 2 carts !?
MegaCart I don't know.

FE3: click, and also here

nbla000 · Post by **nbla000** » Mon Aug 03, 2009 7:10 am

Lozza wrote:and where for images of the 2 carts !?

Each Mega-cart has a custom user firmware, when the new Vice version will be out, all Mega-Cart users will may use a tool to extract their Vice Image, for the moment you may enjoy it just on real hardware

Please be patient...

PS: Lozza, your old avatar was better

carlsson · Post by **carlsson** » Wed Aug 12, 2009 5:07 am

I've had the joy of trying the injector now. Very nice work, and writing to $9E00 isn't much slower than downloading those nearly daily Microsoft Windows updates.

tlr · Post by **tlr** » Thu Aug 13, 2009 12:33 pm

Those MS updates are a few more bytes though...

nbla000 · Post by **nbla000** » Fri Aug 14, 2009 9:33 am

Yes tlr does a very good work, my new SJLOAD patch for IO3 (based on Diddl SJLOAD routines) works very well and now we don't need to overwrite music data to add turbo support for sd2uiec and JiffyDos based drives.

This was possible only with your tool tlr, many thanks again for your work and many thanks to Diddl for his routines of course.

Btw my latest SJLOAD patch works from $9C86 to $9FFD so we need to find a new location for your Vic-Tracker patch, I suggest IO2 $9800-> $987F

PS: I wish release the final SJLOAD patch for all Mega-Cart users with a stand alone program to install the SJLOAD patch without user interaction, just LOAD and RUN, there is a standard way or do I need to hack your INJECTOR a bit

?

tlr · Post by **tlr** » Sat Aug 15, 2009 3:01 am

nbla000 wrote:This was possible only with your tool tlr, many thanks again for your work and many thanks to Diddl for his routines of course.

yw. I'm glad you find it useful.

nbla000 wrote:Btw my latest SJLOAD patch works from $9C86 to $9FFD so we need to find a new location for your Vic-Tracker patch, I suggest IO2 $9800-> $987F

...or you just make your patch 34 bytes shorter...

The vt patch is relocatable so you can just put it where you think it fits.

nbla000 wrote:PS: I wish release the final SJLOAD patch for all Mega-Cart users with a stand alone program to install the SJLOAD patch without user interaction, just LOAD and RUN, there is a standard way or do I need to hack your INJECTOR a bit ?

There is a standard way. From the readme:

Code: Select all

Special feature:

Mega-Inject can be made to automatically inject a binary (after asking).

  1. Copy mega-inject.prg to a new file.
  2. Change the last byte of the new file to $00 (originally $ff).
  3. Append a structure like below to the end of the file:
     0      zero-terminated string shown before accepting.
            (Max two lines + one empty recommended)
     n      Start address to write
     n+2    Last address to write
     n+4... data to write

Example:
    dc.b    "STRINGSTRINGSTRINGSTRI"
    dc.b    "STRINGSTRINGSTRINGSTRI"
    dc.b    0
    dc.w    $9df1
    dc.w    $9e0f
    dc.b    1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19
    dc.b    20,21,22,23,24,25,26,27,28,29,30,31

nbla000 · Post by **nbla000** » Sat Aug 15, 2009 4:24 pm

tlr wrote:The vt patch is relocatable so you can just put it where you think it fits.

OK, I will inform you for the new location in case you want to change your VT patch inside the tar.gz archive.

nbla000 wrote:PS: I wish release the final SJLOAD patch for all Mega-Cart users with a stand alone program ...
There is a standard way. From the readme:

Sorry, i didn't read your readme

Next week I will try it, time for holidays now

Denial

Mega-Cart hacking and writing the NvRAM...

Mega-Cart hacking and writing the NvRAM...

Re: Mega-Cart hacking and writing the NvRAM...