The interview Steve Golson gave to Peter Latimer for RetroGamer Magazine (Volume 2, Issue 2) all those years ago, basically sets in stone the 7800 saga...
The 7800 was simply something Warner Communicatons had 'wanted' and it would be warner that would be convincing Atari that it was great hardware.
Warner had simply asked for a '2600 with more players' (Player/Missile Graphics), according to the quote from Steve, along with 2600 compatibility...
So the only real hands tied aspect was the decision to use a 6502 CPU, although a different CPU given task of emulating the 6502 was considered, but it was soon cast aside.
Steve didn't think the 6502 was too much of a limitation, given what other CPU's were avaiable at the time, espically as it was running at a faster clock speed in 7800 mode, they just had to slow it down for 2600 mode.
Tom Westberg is quoted as saying that when they used the old 2600 graphics chip for sound as well as backwards compatibility, in order to save costs..that was probably a mistake.
Steve talks of the design work on the Maria chip going from nothing to 'tapeout' in about 12 weeks, but at that stage, the chip design wasn't quite enough, you could display lots of objects, but it required too much CPU time from the 6502...so they started working on Maria II.
The original Maria chip design had display lists of graphical objects, which were automatically displayed on each scan line by the DMA hardware, that copied the graphics data into the line Ram.
Every scan line required the processor to update the display list info.
Maria II simply added display list lists!, so Maria II could basically take care of updating the display lists after every scan line, thus freeing up essential CPU time.
The reason i mention this breakdown...I'm NOT a tech guy, but had heard so much hype over the years on other forums from Atari fanboys about this mythical Maria chip in the 7800 and the supposed 'unlimited sprites' it allowed the hardware to process, i thought it important to bring the reality of just what the chip was, at grass roots into the cold light of day.
And, as i've stated time and time before, Steve himself doesn't think the 7800 graphically matched the Sega Master System..so the 7800 doesn't appear to be quite the mythical hardware some UK writers have often claimed over the years.
But back to the sound aspect....
What Tom considers a 'probable' mistake, i think it's fair to say greater % of the Atari community considers a KEY mistake.
Atari had a proven, capable soundchip in form of Pokey, fantastic for sound effects (superior i find in this area often to the SID) and capable in right hands of giving the SID a run for it's money in terms of music.
The 2600 chip? ok for your basic in-game sound effects, but only wanting to include it on specific games, you have created a 2-tier system for your flagship hardware's software, right from the off.
But, going back to Warner Comms original design requirements, it seems clear SOUND was NEVER something given any real consideration..this might be a marketing angle? after all you'd be selling your software based on Magazine images..still shots...sound still an often vastly overlooked aspect to games to this day.
So, unlike the god awful AY soundchip decision used in the ST, i cannot personally lay the real blame at Atari for the decision not to use Pokey as standard in the 7800 hardware.
Eyes more on Warner...