[Coco] CoCo 128-column text mode

[Nick Marentes]

On 8/01/2015 7:37 AM, William Astle wrote:
> On 15-01-07 01:49 PM, Allen Huffman wrote:
>> Without attributes would be nice -- scrolling would hopefully be 
>> twice as fast. I forgot how sluggish PRINT is in 40/80 column mode. I 
>> did some tricks in my MiniBanners (1990) program to make it display 
>> instantly like an assembly program, and now I remember why I did that.
>
> The reason the 40/80 column test display is to painfully slow on the 
> CoCo3 isn't because of the attributes or scrolling. It's painfully 
> slow because the code for displaying a character on the hires screens 
> is <bleeeeeeeeeeeeeeeeeeeeeeeeeeep> terrible.

That is correct. Let's not confuse the speed of the GIME chip with the 
speed of the BASIC interpreter code, especially the Super Extended Color 
Basic additions which deal with writing to GIME accessible RAM.

Remember that the GIME has access to 512K bytes contiguous but the 6809 
can only access 64K via the GIME's MMU.

SECB does not efficiently manage this... just as OS-9/NitrOS9 does not 
efficiently manage GIME resources. Look at what can be achieved by M/L 
programmers who custom write code for games and demos amd show me 
anything under SECB or OS-9 that comes close to the speed.

The same can be said of PC's and Mac's. They seem fast with their 
gigahertz processor speeds and gigabytes of RAM but I bet if the OS was 
written in 100% optimized M/L, the speed would be breathtaking. Of 
course, it means developing code is a lot more difficult and more 
difficult for others to understand.

Optimised M/L... for those with hair on their chest!   :)

Nick