TECH : Phoenix RAM shenannigans

[P-Man]

[ukvac] TECH : Phoenix RAM shenannigans
hi all..

I can't figure out the mame source as i don't speak 'mame driver' language
with a little assistance so far, i've found the following with Phoenix:

program rom is 0000->3FFF

address 4000->43FF is RAM of sorts...
write '1' to address 5000 gives one page of RAM, and a '0' @ 5000 give
another page, both for screen ram one assumes.

Using the fluke, i can identify with an F0/0F mask which 2114 is responsible
for the lo/hi nibbles of ram in each page, however....

There's another 4x 2114 rams on the board which i can't find in the memory
map...

is the register at 5000 responsible for paging any more ram?

also, 4 more roms on there (gfx) that i can't find either

anyone got a decent memory map for phoenix, its not in the schems...

any help appreciated.

Andy



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[junofirstman]

[ukvac] Re: TECH : Phoenix RAM shenannigans
> I can't figure out the mame source as i don't speak 'mame driver'
language
> with a little assistance so far, i've found the following with
Phoenix:
> program rom is 0000->3FFF



You could always look at the original memory map which is included in
the arcade emulator HowTo document, that seems to be bloody hard to
find now..

http://www.atarihq.com/danb/files/aehowto.zip

According to it there is memory at $4000->$43ff (which is 2 2114's)
and memory at $4800->$4bff (another 2 2114's)

The bank switch bit at $5000 controls BOTH areas. So writing a 0 to
$5000 selects the first 4 2114's and a 1 selects the second 4 2114s
which totals the 8 you are looking for..

> also, 4 more roms on there (gfx) that i can't find either

Graphics memory is virtually never mapped into processor space (other
than more recent 68k Konami games)

and yes, that memory map in the FAQ was a damn sight easier to read
than the mame source code.

Chris



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[P-Man]

Re: [ukvac] Re: TECH : Phoenix RAM shenannigans
strangely, i sent that mail to the list during last week sometime.. very odd

but yeah, i finally found the 4800-4bff with assistance from macro.. but....

i toggled address 5001 with '0' and a '1' in order to page flip the higher
memory... works a treat

Andy

[snippety snip]



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