27 replies to this topic

[batari]

Thomas Jentzsch, on Sat Jan 3, 2009 4:59 PM, said:

batari, on Sat Jan 3, 2009 9:02 PM, said:

The "magic writes" in 4A50 are what makes it shine, and would certainly make things better for you.

Can you explain those magic writes for me, please?

Quote

However, if Andrew passes the torch to another programmer, and this programmer wants to use 3E, and can live with about 31k ROM/7k RAM, one could target the Harmony cart as a release platform.

7k RAM won't be enough, since the game heavily relies on self-modfying code.

Magic writes allow for reading and writing to the same address, whereas all other RAM schemes have different addresses for reading and writing. This allows one to use read-modify-write instructions and one could use the full address space as RAM instead of half.

As for the RAM, I vaguely recall in [stella] discussions that much of it was a ROM mirror, with several copies of the same bank with only a tiny change to one of the banks. The Harmony cart could accommodate something like that without using a bunch of RAM.

[Thomas Jentzsch]

Thanks for the info.

Another problem I remember now was, that the fixed bank space was limited to 2k in total. So every RAM modifcation had to be done from there.

[lapetino]

Andrew Davie, on Fri Jan 2, 2009 4:52 PM, said:

I pick it up now and then and have a play.

And I think that's what a lot of us on this board would love to be able to do. Any word on another programmer picking up the mantle? Or should we just start a fund with donations to get Andrew "motivated"?