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#1

C

Technical support - Hardware related / Re: Black screen CPC464 seems ...

Last post by ClintonGoodfellow - Today at 01:24

Hello,

Sorry I haven't updated this thread in a while, I've had a busy lot of months. However I'm now able to spend some time and keen to make some progress.

I have since soldered in the new crystal and the matching caps, but still need to give it power and measure the frequencies.

Could you guys possibly suggest what pins I should be checking with the scope and what the expected outcome should be?

Rowan.

#2

Games / Re: Turrican (128K)

Last post by lightforce6128 - Yesterday at 23:38

For better visualization I append the map, blocks, and tiles of level A (1.1). I suppose this is not a big spoiler because almost everybody will know level 1.1 more than good enough.

#3

Games / Re: Turrican (128K)

Last post by lightforce6128 - Yesterday at 23:34

I think the real difficulties will come with the levels where Parallax is used. Daren used animated tiles to create the effect, where background tiles are "slided" in the Tile Map. This is quite ingenious. Level I (4.1) looks like a real nightmare with a slew of animated tiles (not only for the parallax).

When I first saw this, I was really impressed. Paralax scrolling was not really common for the CPC. Until recently I thought it would use some kind of optical illusion, where the tiles contain the same background, but shifted differently then the tile offset. But this could not be used here, because it would interfere with reusing tiles throughout a level.

I did some further analysis and now have a better understanding about how the drawing works. There are three levels of image generation, not two!

• The map of e.g. size 137x51 contains indices of blocks (not of tiles!).
• There are 256 blocks, each containing 4x4 tile indices.
• Finally there are 256 tiles, each containing 4x8 pixels.

With this trick the game achieves a compression ratio of 118:1 (or reduces the size by 99.2%). The drawn map has a size of 2192x1632 or 3.6 megapixel, while the three data structures only need 14.8 kilobytes.

By looking at tiles and blocks of level I (4.1) I found there are several blocks showing paralax background. But there are only four tiles (index 203 to 206). The whole paralax scrolling magic is done only in these four tiles!

#4

Programming / Re: Newbie assembler CPC quest...

Last post by ZorrO - Yesterday at 22:21

It's cool, have fun as you wish. Just knowing assembler without knowing properties of specialized chips and contents of kernel doesn't give you feeling that you know what and how to do it. Many coders, when switching to another platform with the same processor they know, are unable to do as effective things on new machine as on the previous one. Accustomed to being better than those who write only in Basic, on new one they see that those who don't know assembler can do better things because they know machine. At least at the beginning it is like that.

#5

Amstrad CPC hardware / Re: Which chip for internal ro...

Last post by orzel - Yesterday at 22:07

Not a very elegant solution but you can still source W27C512 ICs. 

Ah, good to know, thx !

What's the reason to avoid EPROMs? They are easy to source and cheap. I always use EPROMs to replace the internal ROMs.

I've seen some on aliexpress, but i'm not confident enough. I assumed those old chips were not available elsewhere. There's none on lcsc for exemple. I can't find any 27c128 anywhere.

For the 27c256, there are indeed stocks on digikey/mouser. But their shipping is very expensive.

Thanks for the tip !

#6

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Technical support - Hardware related / Re: iRAM/640 - Ram Expansion -...

Last post by Blank_Reg - Yesterday at 21:49

Got one of these IRAM640s off eBay a week or so ago. Just tried it in the 6128 today and it appears invisible - ram remains at 128k in Noels tests and in symbos. What have I missed or are their fake ones of these going about?

#7

Technical support - Hardware related / Re: Disc Missing and Bad Comma...

Last post by eto - Yesterday at 21:11

And... according to Murphys Law it was of course the last possible IC: The WDC9216 data separator!

Of course the only IC I could not test with my IC tester. Of course the one that was not mentioned in any other thread ever. 

#8

Programming / Re: Newbie assembler CPC quest...

Last post by andymccall - Yesterday at 21:03

I'm looking at your video to see what effect you want to achieve. And on Amstrad you don't need machine code for this.

Oh, I get this.  This is an exercise purely to learn asm on a few different platforms. In fact the absolute easiest way would be to have a script to display two full screen images - but that's not why I'm writing this.

I started programming when I was about 14/15 when I got DevPac 3 for the Amiga for my birthday, and I just couldn't understand it.  I tried a number of times throughout the years to go back and learn it and it's been a bit of a mental block for me.  About 18 months ago I started getting into retro systems and decided to finally learn how to code in asm.  I've been exploring different modern 8-bit systems like the Commander X16, Neo6502 and Agon Light, and I thought I'd go back to the very first system I ever had - the Amstrad CPC 6128 and see if I could write it for that.

The demo/app isn't for anything, it doesn't really do anything - it's a few loops, keyboard input, shapes, screen mode changes, displaying an image tile or a sprite etc. but it's enough for me to learn a few common skills across a number of platforms.  I'll expand on it to try new things as I learn more.  One thing I've already thought of is having a data structure for all my rects that loop through to display them.  Right now I could do that in C/C++ or Java, but I've got no idea about this in asm so it will be fun learning.

#9

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Technical support - Hardware related / Re: old model 464 with garbled...

Last post by salvogendut - Yesterday at 20:30

After Swith On CPC. ROMDIS line to Vcc

O screen You should see narrow stripes.

Hey thanks for replying! I am not really familiar with the platform so if you could elaborate a bit what ROMDIS is and what should I do with it, that'd be super helpful!!

#10

Programming / Re: Newbie assembler CPC quest...

Last post by ZorrO - Yesterday at 19:57

I'm looking at your video to see what effect you want to achieve. And on Amstrad you don't need machine code for this. You can do it in a few lines of Basic or even display such a screen as a text file with a few control codes. For the address text you can use characters with codes from 128 to 143, and for option font use narrow font with a 4x8 pixels matrix in MODE 0, or switch bottom of screen to MODE 1. Last one thing can't be done in text file. The only difficulty is to get a lighter gray color that is not in palette, there are 3 ways to do this but each has a certain drawback.