fisher@dvinci.DEC (03/12/85)
<Sacrificial line>
I recently upgraded from an Atari 400 w/32K to an 800XL with the full wad of
64K.
What I thought was strange was that when I tried my LOGO cartridge, it showed
no more nodes (memory available) than I had with my 400.
I tried the following algorithm in both LOGO and the builtin basic:
address = 0
loop while (address < 64K)
temp = peek(address)
poke address,127 !Put distinguishable number in mem loc
if peek(address) = 127 then print "ram",address
else print "rom",address
poke address,temp
address = address+1024
end loop
As expected, Basic showed 40K of RAM available (40-48K=basic code,
48-64=OS ROM, hardware registers, etc etc). The odd thing is that LOGO
showed there to be only 32K.
My old hardware manual says that RAM is usable between 32K and 40K if there
is no right cartridge in the non-XL 800. Is an 800XL different? Is a LOGO
cartridge different (has 16K?)
BTW, is there any software which uses the memory above 40K by bank-switching
or whatever?
Burns
UUCP: ... {decvax|allegra|ucbvax}!decwrl!rhea!dvinci!fisher
ARPA: fisher%dvinci.dec@decwrl.ARPAravi@mcnc.UUCP (Ravi Subrahmanyan) (03/13/85)
The XL's do have 64K, but the 'extra' 16 K is hidden beneath the
cartridge, and as you rightly guessed, is not usually available, in
fact hardly ever available. OSS (optimised software systems) does make
bank switched cartridges for the Atari; called 'Supercartridges', their
BASIC XL, ACTION!, and MAC65 are in those cartridges, which basically
are 16K carts. which appear to the machine to be 8k carts, and which
bank switch to give you an extra 4K. They also sell DOS XL, a true
double density DOS which can use some of the memory that exists in parallel
with the OS to give you some more (beyond the supercart); DOS XL can be
used with any XL machine to get this extra memory, not just with supercarts,
though they work together to give even more.
-Ravi