Posted By
MMS
on 2016-09-21
13:53:26
 |  Re: What would I do differently in the Plus/4
OFF
just from this single topic point I learned a lot of new and useful things. Many thanks! 
LITWR: your points are crystal clear.
Questions:
-did you inspected the circuit diagrams, how the double frequency generated for the borders by Plussy, and is there any chance to make it quad frequency easily? I remember it was mentioned once previously. What could be the side effect?
-As I see, the PAL and NTSC rastertime/bandwidth do not let 80 chars in a row, as it expecting 640 pixel horizontal resolution. The 62 chars is an interesting option, one step closer to NLQ printers.
I did not fully understand it before, why then the PC CGA could be connected to a TV with composite output, as it had 640x200 and 80 char mode.
Now I checked it, and fully understood the situation, even IBM could not solve this TV system limitation:
"IBM intended that CGA be compatible with a home television set. The 40x25 text and 320x200 graphics modes are usable with a television, and the 80x25 text and 640x200 graphics modes are intended for a monitor."
-1571: the 1540 and 1541 are slow because it uses SW bitbanging, due to a HW bug in VIC-20 and C64. If the Plus/4 would have used a corrected one, free from this defect (existing in an IC produced already in millions as I know), then the 1571 could be used in the same way as with C128.
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