Hi,

I've a question about the different "bank" of tiles used in screen 2 or screen 4

in these screen modes the area is splitted into three regions upper,middle,bottom. Each of these is 32x8 wide. So there are 256 possible charaters. The attribute/pattern table describe all of those 256 charaters. Because each region have it's own name table/charater/attribute table no problem at all. This arrangement make possible to address each pixel in a indipendent way.

On msx2 the displayed area can be 212 in height and the screen page area is 256.
From the vdp point of view a screen is 256x256 pixel wide, with a viewport of 256x192 or 256x212 pixels.

Problems come out if i want to take advantage of screen 4 and i have a 256x256 pixel screen area, what is unclear to me is:

a) the vdp does not have a fourth "bank" of tiles for coordinates between 193 and 255, so probably is uses the bottom area. That is the 3 bank is 512 charathers wide instead of 256 and have only 256 definable patterns -> cannot have individual pixels addressable. This third area is "asymmetric" if compared with bank top and middle.
b) the vdp have a fourth area. I think is not possible the pattern and attributes table will need 8192 bytes instead of 6144.

I think the truth is (a). But i'm not sure. Can anyone confirm this?

Thx.

mode 256 x 212 is only on screen 5 , 6 , 7 and 8

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mode 256 x 212 is only on screen 5 , 6 , 7 and 8

only in basic. No one prevent us to set the appropriate vdp register to achieve 212 lines on sc0-sc4.
The question is: once we have a little larger area how are arranged the tile banks?

b

Space Manbow uses 4 tilebanks, afaik, but when keeping in mind that it scrolls vertically, it only makes sense.

E.g. scrolling 4 tiles down means you see:

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So, there *must* be 4 banks..

change vdp(10)=128 just change position of point (0,0) but don't change the height of screen2 and screen 4 in basic
always 192 : why is not the same in z80 machine code ??

Quote:

Space Manbow uses 4 tilebanks, afaik, but when keeping in mind that it scrolls vertically, it only makes sense. So, there *must* be 4 banks..

I've tryed to fill the first three banks with same patterns+attribute data, effectively i can see the same patterns in all charather screen-

I also think there are a lot of collisions, however.
Normally the pattern table is from 0 to 6144
If we have 4 banks those table reach from 0 to 8191 overlapping name table+sprite attribute table.
The same problem also apply to the color table, overlapping sprite pattern info, probably i need to relocate those tables, but i'm not sure can work.

the new layout should be
0-8191 pattern table (4 banks)
8192-16383 color attributes

sat e spt will be moved outside the first 16KB.... and also nametable...



Anyone have already tryed?

You can put the tabels anywhere you want within some restrictions.

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You can put the tabels anywhere you want within some restrictions.

Yes, i know, thanks, what i suspect is that the fourth bank is not working. but wolf told me that space manbow uses it.... so....

You can use the 'mirror' bits to set several combinations. Like all the same as the first, or 1st same as 2nd + 3th same as 4th, and some other.
Space manbow has an actual game area screen height of 180 pixels witch saves 192-180 = 12 lines to update name table (hence 1 tile 8 lines heigh). So theoreticaly manbow could be using only the first three sets (by using Reg 23). And Manbow's vertical scroll is done in exactly the same way they scroll horizontally. So long story short I think wolf is wrong... at least this time.

hmmmz, well I have my sources.. but, I shall investigate an punish the guilty ones..

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You can use the 'mirror' bits to set several combinations. Like all the same as the first, or 1st same as 2nd + 3th same as 4th, and some other. Space manbow has an actual game area screen height of 180 pixels witch saves 192-180 = 12 lines to update name table (hence 1 tile 8 lines heigh). So theoreticaly manbow could be using only the first three sets (by using Reg 23). And Manbow's vertical scroll is done in exactly the same way they scroll horizontally. So long story short I think wolf is wrong... at least this time.

@GhostwriterP: emh, no. I think i was not able to explain my idea:
i do not want some mirroring. I want ALL four bank independent.

Ok, whether SM uses them or not, there are 4 banks in sc4!

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Quote: You can put the tabels anywhere you want within some restrictions. Yes, i know, thanks, what i suspect is that the fourth bank is not working. but wolf told me that space manbow uses it.... so....

Why do you suspect it won't work? It does work. Trust me

You can just try it in basic. set screen 2, scroll up the screen, and vpoke whatever you need to see it already works the way you want.

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change vdp(10)=128 just change position of point (0,0) but don't change the height of screen2 and screen 4 in basic always 192 : why is not the same in z80 machine code ??

when you do vdp(10)=128, basic does not know the height has changed. basic will never use those extra lines, but you can use vpoke to use them.