Atari 800 upgrade to 65c816 (nice and simple)

[Sloopy Malibu]

Evan Samuel (esa...@iamerica.net) wrote:
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: This is the upgrade to a 65c816 for early model 800 Atari computers.

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: This is all you have to do. Remove and replace the cpu, and place a Jumper
: wire at A303 pin36 to Z302 pin 5. Then the 800 becomes 16 bit. You will
: not notice any chances when you power up because the 65c816 powers up in
: 6502 mode. To take advantage of the cpu, you must write your own programs
: to utilize the advanced features. NOTE: When your 16 bit software runs,
: you must disable the IRQ, and Vertical Blank Interupt to prevent a system
: crash with your 8-bit ROM operating system. As for the memory upgrade.
: I'll check my notes and let you know. Its not difficult, but not as easy
: as the CPU. During the last year or so of production of the 800. Atari
: had upgraded the 800 CPU CHIP to the XL CPU CHIP. This mode is more
: extensive, due to the missing chips used on the old board. To upgrade
: these boards the missing chips must be reinstalled with the 65c816 using
: a piggyback board. The 6502C is not 100% pin compatible with the older 6502,
: so the board must make the neccessary pin changes.

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also if you get a 65802 you can pop it right in and it works fine.... ( i
posted this finding when i was in college about 5 years ago....but... ;')
the 65802 is a 65816 with a 6502 pin out on it...as for a supply of
65802's.... hmm leave me mail and i will look in a few places if anyone
is interested....

sloopy.

slo...@magpage.com
--
____
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[Evan Samuel]

The one difference between the 65802 and 65816. The 65816 will address
16Meg of memory while the 65802 will address only 64k memory.
The 65802 will not replace the 6502c in the XL/XE atari computers.
These cpu's were customized for atari, and several of the pins have
been changed.