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Is a NEC 7220 useful for games?


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#1 Gatherer of Data OFFLINE  

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Posted Fri Feb 23, 2018 3:29 PM

I recently read a lot about different obscure computer systems of the 80s, including ones from East Germany,  and noticed that some had this graphics controller (or a clone of it). I also recently read a bit about the CPC and how the Z80 was burdened with a relatively RAM heavy screen. Some of the systems that were equipped with the NEC controller could do high resolutions, but also in color. This was presumably mostly intended for business graphics, but does anyone have an idea to what extent games and a CPC-like system with a relatively weak cpu could possibly benefit from it?

 

The PC-98 line listed at the wiki page of course had a lot of games, but those systems had a 16bit 8086 from the beginning, and there weren't that many action games in the relevant time period to see what it might be capable of. I think the graphics system might also have been upgraded in later models already in the middle of the 80s? There's a high res Karateka for instance, but I've read it required the VM model which came out in 1985.

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The Epson QX-10 used a 640x400 resolution and could do 8 colors  as well, but it was only equiped with a Z80.

 

One of the computers that isn't listed there that I read bit about and where I checked out some docs to discover it had the 7220 was the Canon AS-100, which was another X86 IBM incompatible. It also had  a 640x400 8 color display, but interestingly, the palette is supposed to feature 27 colors (the same ones as the CPC?). The CPU was a 8088.

 

 



#2 rpiguy9907 OFFLINE  

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Posted Fri Feb 23, 2018 10:05 PM

Well the 7220 could draw lines and such and was completely bitmapped but it did not contain a blitter so moving things around was all CPU work. This is probably why the Epson QX-10 was slow scrolling, even in CP/M, compared to machines that had character graphics.

It also had an 8-bit data path that topped out at about 5Mb/s theoretical over ISA, probably half that in practice. Not good for high-res games.

The fastest video cards using the 7220 included a dedicated micro controller or CPU on the graphics card to act as a blitter and co-processor. For example there was fast EGA card that had a dedicated 286 on it along with the 7220.

Colors were, if memory serves, just a matter of adding bitplanes (which require multiple trips to memory for a single pixel) and at least for the Epson and early cards was limited to what a digital monitor could display.

So it allowed bitmaps but really wasnt suitable for action games by itself. With a coprocessor onboard maybe, but probably still not at 640*400.

Edited by rpiguy9907, Fri Feb 23, 2018 10:07 PM.


#3 Gatherer of Data OFFLINE  

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Posted Sun Feb 25, 2018 9:18 AM

Colors were, if memory serves, just a matter of adding bitplanes (which require multiple trips to memory for a single pixel) and at least for the Epson and early cards was limited to what a digital monitor could display.

So it allowed bitmaps but really wasnt suitable for action games by itself. With a coprocessor onboard maybe, but probably still not at 640*400.

 

Yes, I didn't realize this before, but the majority of these early computers stuck to the 8 color model because monitor options were limited.

The most color capable of home systems (outside of specific ones for CAD etc.) before the later PC-98 models seems to have been the DEC Rainbow, the palette was extended to 4096 and it could display 16 colors in medium resolution mode, which meant in this case 384x240. The 7220 was apparently modified in various ways, e.g. some docs I've seen mention a scroll map.


Edited by Gatherer of Data, Sun Feb 25, 2018 9:19 AM.





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