3 ms·

> EC68020 which would have increased the bus bandwith by 4 times. I thought it was only 2x (16 bit bus on the straight 68k). It did also have a cache though wh

> EC68020 which would have increased the bus bandwith by 4 times. I thought it was only 2x (16 bit bus on the straight 68k). It did also have a cache though which likely would have helped muchly. Wikipedia does indicate the EC68020 was considered for the Jaguar 2. My gut would be that the EC68020 was considered 'too expensive'; back then 130k extra transistors still meant a few bucks from a cost standpoint, and Atari was already cutting odd corners in a desperate stupor. That bus is terrifyingly bad IMO, I remember developers lamenting it in interviews I've read over the years. One of the -smartest- things Sony did with the Playstation was picking an architecture that was known to be capable of 'pushing graphics' and licensed/reused what they could from SGI's system designs. Probably a big part of why, while still challenging for it's age, it was at least -sane- compared to what was involved on the Saturn (lol, quadratics) or the Jaguar. Nintendo, while late to the 32 bit party, also went with an SGI based architecture, but stuck with ROM carts which still cost them a bit of business. Funny, the TG-16 suffered from many of the same problems as the Jaguar (specifically, questionable CPU bus sizes and quirky hardware design). Alas, it seems nobody from Atari payed attention to that lesson.

alexisread 7y ago
Yes you're right, technically it's 2x bus speed moving 16->32 bits, but I was guestimating the effect of the cache to allow the 020 to stay off the bus ie. interleave cache and bus access. What would have made more sense would be for the object processor be dropped, so Tom and Jerry could be placed on the same chip with some scratchpad ram to share amongst the processors. You'd have a big cost saving on a single chip system, and you could also move to 1.5mb dual bank ram probably at price parity. 020 probably would've been too expensive, but you needed to go large or go home in the console world, I'd have gone with CD to drop the ROM costs so hopefully over a year projection the upfront hardware cost would amortise with the CD savings. A single chip might have allowed an 020+CD at a $300 launch price rather than $250. The Saturn architecture is a completely bizarre kettle of fish even vs the Jaguar! I can see where the pinch points were for the Jag, but the Saturn looks as though they redesigned the machine twice, and without actually having any input from the AM2 team (Virtua fighter). Certainly from a systems perspective there's a lot of scope for making it more efficient. I kinda of thought the TG-16 was straightforward from a programmer perspective? The custom chips had a few things they could do and that's it. The demos I've seen (pouet) basically seem to use the hardware as it was intended ie. no fancy tricks that you can coax out of it. I'd say the SNES was more crippled by bottlenecks, probably stemming from the initial backwards NES compatibility that never materialised?

alexisread 7y ago

Yes you're right, technically it's 2x bus speed moving 16->32 bits, but I was guestimating the effect of the cache to allow the 020 to stay off the bus ie. interleave cache and bus access. What would have made more sense would be for the object processor be dropped, so Tom and Jerry could be placed on the same chip with some scratchpad ram to share amongst the processors. You'd have a big cost saving on a single chip system, and you could also move to 1.5mb dual bank ram probably at price parity. 020 probably would've been too expensive, but you needed to go large or go home in the console world, I'd have gone with CD to drop the ROM costs so hopefully over a year projection the upfront hardware cost would amortise with the CD savings. A single chip might have allowed an 020+CD at a $300 launch price rather than $250. The Saturn architecture is a completely bizarre kettle of fish even vs the Jaguar! I can see where the pinch points were for the Jag, but the Saturn looks as though they redesigned the machine twice, and without actually having any input from the AM2 team (Virtua fighter). Certainly from a systems perspective there's a lot of scope for making it more efficient. I kinda of thought the TG-16 was straightforward from a programmer perspective? The custom chips had a few things they could do and that's it. The demos I've seen (pouet) basically seem to use the hardware as it was intended ie. no fancy tricks that you can coax out of it. I'd say the SNES was more crippled by bottlenecks, probably stemming from the initial backwards NES compatibility that never materialised?