vidak's Blog

On paper specs can be deceiving. It's more a case of "technically different", rather than "technically superior". In summary, the 7800 is "better" at producing large numbers of sprites than the NES, with a more generous sprite definition as well (maximum sprite width=32 bytes on the 7800, rather than 8 pixels on the NES) . The NES is "better" at tile based manipulation, and also doesn't lose anywhere near as much CPU time to screen preparation and rendering as the 7800 does.

 

At higher resolutions MARIA, the 7800 DMA chip, gets bogged down by churning through the background tiles, which eats quite a bit into how many sprites it can actually render in any given horizontal zone. It's one reason why the 160 pixel resolution mode is often preferred.

 

The screen prep CPU time can be mitigated a fair bit by double-buffering on the 7800, but it's rarely done because it generally requires cart-based RAM. Here's a double-buffer demo that moves 40 non-flickering sprites around the screen.

 

 

Anyway, rarely is one console of a similar generation "technically superior". Many may consider the Intellivision and Colecovision superior to the 2600, but as you know, the beam-racing architecture of the 2600 and more-or-less enforced 60Hz game speed allow it to be superior to both in certain narrowly defined ways.

Yeah I found this link from the wikipedia page:

https://sites.google.com/site/atari7800wiki/7800-compared-to-the-nes

It says all the same things as you - the 7800 is frequently caught up in spending much more time than the NES rendering the display.

 

There's also some issues with outputting the image due to the way the analogue video is clocked. Apparently there is potential for artifacting with the 7800.

 

The memory is also unified in the 7800. The article I linked argues this presents some disadvantages compared to the NES with it's dedicated video RAM.

 

Anyway, you're right, really. They're just radically different architectures.

Yep, I was about to give you that link, but you beat me to it.

It really comes down to how much CPU time is available. While the 7800 GPU is capable of displaying more sprites (total and per line) than the NES PPU, each 7800 sprite requires a significant number of CPU cycles to move around the screen, whereas on the NES the CPU cycles are trivial. Then to make matters worse, because of the unified memory the 7800 CPU loses even more cycles for each sprite & tile displayed.

The Epoch Super Cassette Vision (1984) is said to be able to put out 128 sprites on the screen, but with the limitation of 7 or 8 per raster line if I recall correctly. Despite that fact, I wouldn't claim it is superior to the Famicom or SG-1000.

 

I understand the SMS has an updated VDP compared to the SG-1000 and possibly other improvements that actually makes it far more powerful than what one first might imagine, one of the top Z80 based home systems.

 

The 7800 on the other hand is a big void in my recognition. I may have seen a console once or twice, some screenshots but its technical capacities are among the black holes of my video game awareness. Of course I could remedy that by looking it up, but as I already have so many interests I have let it slip.

Yeah, you're right.