Re: [stella] Re: 2600's TIA
Subject: Re: [stella] Re: 2600's TIA|
From: Kevin Horton <khorton@xxxxxxxxxxx>
Date: Sun, 19 Aug 2001 18:48:52 -0500
At 02:30 PM 8/18/01 -0700, you wrote:
The schematic that Curt is offering was generated much much later. It was
given to GCC to integrate into a proposed MARIA/TIA combo chip. So it's a
schematic of the final (working) TIA design.
OK, that's even better then 'cause it is probably bit more optimized than
the original, and very well may be the very set used when Atari went to
Ricoh to have the real "2600 on a chip" made for the very late 2600
Jr's. It is in a 64 pin shrink DIP package.
Interestingly, the part# of this custom chip is nearly identical to that on
the NES' own processor chip... (NES processor chip is the RP2A03, while the
2600 on a chip is the RP2A10). I highly suspect this is a 6502 core +
custom logic "standard" chip that Ricoh had in their product lineup,
allowing customers to use a 6502 core and add on basic functionality. The
NES chip has the audio circuitry, a DMA dealie, address decoding, and some
interrupt controlling on it along with a clock divider, 3 bit output port,
and some other things with the usual 6502 core. The 2600 chip of course
has the 6502, TIA, and RIOT functionality on it.
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