Hardware Scrolling and Sprites

[Misel982001]

Hello guys. I have had a discussion on youtube with some guys who insist that the CPC has hardware scrolling and sprites. To my knowledge this is not true, this why the scrolling in most games is jerky. Can you enlighten me?

[roudoudou]

scrolling capabilities does not mean it can be used everytime


most of game scrolling are software


hardware sprites available with CPC+ only and not really usable

[robcfg]

As far as I know, the biggest problem is that the video memory of the CPC (16Kb) is too big to be filled in a single frame.


The Spectrum has only 6-7Kb of video memory, so it's faster to fill.


Please correct me if I'm wrong.

[TotO]

The CPC can do hardware or software scrolling, but only software sprites.
The PLUS can do both.

[andycadley]

The original CPC has hardware scrolling, but only in character sized increments (8 mode 1 pixels). There are hardware tricks for making scrolling in smaller steps. It has no hardware sprites at all.

The Plus/GX4000 machines augment this with 16 resolution independent hardware sprites and additional hardware pixel shifting that, in combination with the existing hardware scroll, allows for continuous single pixel scrolling in any direction and in any Mode.

[Rhino]

What everyone should know is that Amstrad can do much better than any other 8 bit computer with its hardware, as soon as it begins to using a bit of its true potential...

To see a preview of the most technically advanced game on Amstrad so far, and probably the best game on 8 bits, just wait until October.

[ivarf]

What everyone should know is that Amstrad can do much better than any other 8 bit computer with its hardware, as soon as it begins to using a bit of its true potential...

To see a preview of the most technically advanced game on Amstrad so far, and probably the best game on 8 bits, just wait until October.

The like button is really not enough here!  Will it be possible to buy a physical copy when the game is finished?

[ivarf]

scrolling capabilities does not mean it can be used everytime


most of game scrolling are software


hardware sprites available with CPC+ only and not really usable

About sprites on the plus, is this an issue when using real cartridges or only when used though RAM?

[andycadley]

About sprites on the plus, is this an issue when using real cartridges or only when used though RAM?

The RAM arrangement, even on a 128K, is really not very helpful when it comes to using sprites. It is very evident that the Plus hardware is designed around using cartridges, whose memory paging arrangement is much more convenient for accessing the new features and still being able to directly access banked memory.

But the idea that the hardware sprites are "mostly unusable" is complete and utter nonsense. Sure, they can't be multiplexed as easily as C64 sprites, but they can still provide significant benefits.

[roudoudou]

About sprites on the plus, is this an issue when using real cartridges or only when used though RAM?

sprites on the plus have dedicated memory, so you have to copy data into it which is very slow


i think Amstrad had in mind to assign sprites for bullets/static objects in games


if you except Prehistorik 2 and the parallax palm trees, it's a very basic usage

[arnoldemu]

In Amstrad Action they claimed the Plus would have 64 sprites.

With 64 sprites it is much easier if you need to upload them into ram and keep them static then change x,y coord only. The sprites would be easy and more powerful.

Maybe they planned this but had to cut it when they found the cost was too much?

The alternative is like C64 where sprite data is read from ram.

There is no bandwidth in normal display. It could be done in border but you could not read all 16.

If restricted to border you have 48 bytes you can read with normal screen display. That is 3 sprites (if 1 pixel per sprite), or 6 sprites (if 2 pixels per sprite) and then you need to store these pixels before using them.

So we have 16 sprites we must upload... we must show there are clever ways to use them and to show they are good.

[HAL6128]

Look at "Edger Grinder", "Relentless" or "Mission Genocide". They show such a good scrolling capabilities, definitiv not jerky.

[fgbrain]

Even on cpc plus, it is not possible to set the hardware scrolling into a specified smaller window!!
Instead we're using the hardware splitting register to use multiple screens into one frame like on plain CPCs

Regarding the sprites, yes it sucks that the addresses are fixed & limited only into ASIC RAM.
Moreover there are no registers to manipulate HW sprites (sizes, flip, rotate, scale...)!

Still I would prefer a blitter installed instead of all this crap IMHO.

In Amstrad Action they claimed the Plus would have 64 sprites.

BTW are we sure there are no other useful but undocumented functions in ASIC chip??? 

[robcfg]

Well, I have the decapped ASIC pictures (which are insane), and you can clearly see the 16 sprite data banks and the two dma sound data blocks.

If there's any hidden functionality it's going to be hard to find...

[Rhino]

The like button is really not enough here!  Will it be possible to buy a physical copy when the game is finished?

Well, I do not know whether to sell physical copies will be possible as it is not an original game, but a conversion of a top classic Amiga game, so we should get distribution rights. I think we'll do a very limited edition only for development team members.

[fano]

Maybe they planned this but had to cut it when they found the cost was too much?

I think so, that would make the chip too big and too expensive.

So we have 16 sprites we must upload... we must show there are clever ways to use them and to show they are good.

Amen, i am pretty sure there are some great things to do with it, just have to find the best way to use them !


Btw , there are a lot of things to do on Plus/GX , commercial games didn't exploit it to its full potential, now we have C4CPC we hope to make great games for it =)

[arnoldemu]

Even on cpc plus, it is not possible to set the hardware scrolling into a specified smaller window!!
Instead we're using the hardware splitting register to use multiple screens into one frame like on plain CPCs

it's not possible on c64 either!
For example: Operation Wolf on C64 moves the panel!

Still I would prefer a blitter installed instead of all this crap IMHO.

BTW are we sure there are no other useful but undocumented functions in ASIC chip??? 

no bandwith for blitter I don't think unless it hogs the bus and stalls CPU. CPU and ASIC are sharing the memory.

The only undocumented stuff appears to be status registers nothing useful I don't think.

(crtc in plus has two status registers).

I wouldn't mind a look at the full resolution asic die shots - not that I would understand it LOL.

I'm waiting for gerald to reproduce it in a FPGA

[EgoTrip]

hardware sprites available with CPC+ only and not really usable

I take it you've never played Switchblade.

[arnoldemu]

I think they mean that it would be harder to replace all sprites in a game with h/w sprites.

an edge grinder like game using plus sprites would work because the number of sprites in that game is limited on purpose and it doesnt change how it plays.

i think clever use is needed for other games or maybe design games within the limits.

or mix software and hw to gain more.

[roudoudou]

Well, I have the decapped ASIC pictures (which are insane), and you can clearly see the 16 sprite data banks and the two dma sound data blocks.

If there's any hidden functionality it's going to be hard to find...

is the Asic picture released somewhere?

[Misel982001]

Τhanx guys!

[TFM]

To see a preview of the most technically advanced game on Amstrad so far, and probably the best game on 8 bits, just wait until October.

Meanwhile look and learn from Burnin Wheels (MODE 0 single pixel scrolling) and Giana Sisters (MODE 0 overscan smooth scrolling). 

Moreover there are no registers to manipulate HW sprites (sizes, flip, rotate, scale...)!

The 6128 Plus hardware sprites can be individually zoomed in X an Y with factors 1, 2 and 4. 

[robcfg]

is the Asic picture released somewhere?

Yes!