Amstrad CPC/CPC plus "fanboy" thread

[Tigerskunk]

That racing game looks really amazing.

[Megol]

Originally Posted by dlfrsilver

the CPC has no custom hardware ? But the CRTC is a custom chip ! It's a sort of black box !
the CRTC on the CPC is the main key. This chip has more abilities than anyone thought back in the 80's. It can do line-per-line hardware scrolling !

At least two of the CRTC variants used by the CPC are standard off the shelf CRTCs so how can you call them custom? The CPC+ series have a genuine custom chip though.

Tweaking registers to make a chip do something it wasn't designed for isn't something directly supported and something done in spite of the chip trying to hinder it.

[dlfrsilver]

Originally Posted by Megol

At least two of the CRTC variants used by the CPC are standard off the shelf CRTCs so how can you call them custom? The CPC+ series have a genuine custom chip though.

Tweaking registers to make a chip do something it wasn't designed for isn't something directly supported and something done in spite of the chip trying to hinder it.

Many operations are not well documented about the CRTC on the cpc.

[Megol]

Originally Posted by dlfrsilver

Many operations are not well documented about the CRTC on the cpc.

No but the operations is register writes upsetting the internal timing of the chip. They aren't documented as the effects are glitches and not guaranteed to work.

AFAIK there is no way to generate a "valid" video signal while doing horizontal scrolling using a CRTC due to the scrolling being done by manipulating sync signals however I may be wrong.

[Capitaine]

Docs !
One of my very first memories of the CRTC is a technical article, Amstrad Mag #27 page 52
At the end it says :

"Fun time, try the following line [Basic] :
OUT &BC00,8;OUT &BD00,1
I have personally called that line the Parkinson's disease"

The grid above says "Register 8 : interlace mode"


For years, I had no ideas of what it was for, except a funny effect. Even not after I moved on to the C64.
I finally guessed it years after, when hacking on Amiga.


Also, if you checkout the Amstrad user manual it says "There are 640 horizontal pixels by 400 vertical" chapter 1 p.58
It was a joke... you could only draw 640x200 pixels. The scale is actually 640x400 but it only draws 1 line out of 2.
I did some tests to make sure my drawing program had not any bug... I was simply stuck at 640x200.

Later when I traded my Amstrad for a C64, the guy gave me a lot of stuffs, with this.
Proper docs and a new world.

[roondar]

For the few still not believing this is a real CPC thing, the creators have responded on YouTube and said:

Originally Posted by Batman Group

...the goal is to launch it in 2 versions: disk(s) and cartridge. Disk version will be a lite version and will not support 464 without memory expansion, cartridge version will run on any CPC and this is why we say that it will be compatible with all CPC models...

So it's definitely real and will run from disk on a 128KB Amstrad, though I'm not too clear what the whole 'lite version' means.

[Retro-Nerd]

This could mean that they maybe stream some stuff like animations, graphics, music directly from the cartridge.

[Capitaine]

It's a great game thanks to additionnal hardware.

Back in the time, there were many CPC 464, and RAM was expensive.
For 64KB you had to splash out 500-600 Fr (today 130-155 €)

So with hardware becoming cheaper Amstrad is "Amiga contender" ?

[Megol]

@Capitaine
I sometimes enabled interlaced mode on my Wang PC which resulted in nice rectangular pixels instead of the standard round-ish dots.
Not sure if that could hurt the monitor, AFAIK there were no visual change except for squaring up the edges of pixels.

[Capitaine]

Was it CGA ? Maybe it fails to synchronize even and odd frames. When failing to do so on Amiga, pixels look weird too.
But I have no clue about hacking on 80-90s PCs, I never had any back in the time.

[LongLifeA1200]

No update from BG on "Vesperinto" as yet.
Another must been seen to be believed project.
Rhino's quest to prove that the Amstrad CPC was the 8-Bit King.
Hopefully he'll discuss in detail how everything worked afterwards.

[lmimmfn]

It'll come. For sure this is using the CRTC as much as possible, using the HW to shift the track left/right(similar to the Amigas copper) freeing up the CPU.
Its real, its very impressive but like Pinball Dreams, initial showing to available demo took quite some time.
I have faith , i do hope they reveal how it was done as for the CPC it is magical

Wont comment on CPC being king but so few games used its capabilities properly that honestly its shocking looking back at some games.

[dlfrsilver]

Of course it's shocking, but unfortunately, there was 2 worlds opposed :

On one side, the commercial developpers at the time, who were using common assets for their games, and very often too common code.

the thing is that you can't have a good game using the most efficiently a computer, when you use a hardware developpement system.

The most speakable example of this is the case of Palace Software. They used an hardware dev system, which had the particularity to be like this :

For Barbarian, the main and base asset and source was the C64 version. Their system was able to convert the assets for tons of other plateforms, and also convert line by line the original source code.

The result of this ? Barbarian is a mess. On the CPC, the game uses like the C64 version a fixed screen with no scrolling, and 2 poor sprites.

With Palace dev method, the CPC loses more than 50% of its ressources for useless operations. Simply because it is emulating the C64 version. How is that happening ?

The CPC version of Barbarian use directly the C64 assets. Instead of converting by hands the assets, they made the CPC pick the C64 sprites, convert them to CPC mode 1 4 colors, and then in mode 0 16 colors.

Do you imagine the useless works the CPC has to do to perform this bullshit conversion ?

Next, the CPC program code is an inefficient, unoptimised line by line conversion of the original 6502 source code. It's not z80 native code at all.

And then you have the commodorists of the world coming at you saying that the CPC is underpowered !

The other side were the demo makers on CPC. They started coding on CPC, and reached very quickly results far beyond what the commercial coders were able to fork out !

The CPC innerworkings, the CRTC/GA and their intricacies were handled and practised since.... 1989 ! What we see today has not been discovered early 200X, but 32 years ago !

They know since long how to make good hardware scrolls with double barrel buffer, etc, etc...... coupled with top sprites routines.

[Bruce Abbott]

Originally Posted by Capitaine

It's a great game thanks to additionnal hardware.

Back in the time, there were many CPC 464, and RAM was expensive.
For 64KB you had to splash out 500-600 Fr (today 130-155 €)

'Back in the time' I had a CPC664, which was only produced for a very short time. The 664 was basically a combination of the 464 with the optional disc drive built in instead of the cassette tape drive, in a more ergonomic case and cheaper. IMO it was the nicest of all the CPC series, and I regret throwing mine away even though I have a mint condition 6128.

Many 664 owners got upset about the 6128 with its extra 64k internal RAM being released so soon after they had bought their machines, but not me. I unsoldered all the 64k RAM chips and replaced them with 256k chips, then designed a bank switching circuit compatible with the 6128 that could access the entire 256k, to a produce a better machine than the 6128!

After the 6128 was released the 464 was considered to be an outdated 'entry level' model, but as with the base model A500 a lot of software was still produced for it due to the larger installed user base. I hacked a lot of cassette games to run them from disc, much like we use WHDLoad today to load Amiga floppy disk games from hard drive.

Considering that the 464 can be upgraded with a disc drive and extra RAM, both of which were readily available and commonly used at the time, I don't think it's unreasonable to produce games for that setup. Targeting the CPC Plus range is more problematic because earlier machines cannot be upgraded to an equivalent spec. It's particularly frustrating for those of us living in countries they were never sold in, since importing vintage computers from overseas is dicey (and expensive!) in today's Covid-ravaged world.

So with hardware becoming cheaper Amstrad is "Amiga contender" ?

Not really, but it's amazing what has been done with games like Pinball Dreams that show what can be done when you push the hardware to its limits, which is an Amiga tradition. Another nice thing about the CPC is the well designed and documented OS. It's not a contender for the Amiga there either, but was good introduction to writing 'system friendly' apps using functions that were powerful and efficient enough to be useful (unlike most earlier home computers), and this too is an Amiga tradition.

The CPC Plus with its 4096 colors and sprites and DMA sound is even more like the Amiga without being a contender, and I wish I had one to play with. Maybe one day...

[Bruce Abbott]

Originally Posted by dlfrsilver

Of course it's shocking...

For Barbarian, the main and base asset and source was the C64 version. Their system was able to convert the assets for tons of other plateforms, and also convert line by line the original source code.

The result of this ? Barbarian is a mess. On the CPC, the game uses like the C64 version a fixed screen with no scrolling, and 2 poor sprites.

With Palace dev method, the CPC loses more than 50% of its ressources for useless operations. Simply because it is emulating the C64 version.

Even more shocking are all those ZX Spectrum games that were ported to the CPC with the Spectrum's crappy screen mode emulated, complete with color clash!

But some games, such as Jon Ritman's Batman, were given the full CPC treatment, and they rock! It would be nice to see some of them ported to the Amiga with similar treatment.

you can't have a good game using the most efficiently a computer, when you use a hardware developpement system.

But when the alternative is no game at all... a 'hardware development system' gives software houses the ability to churn out mediocre ports that make them extra money for little cost, while enhancing the perceived value of their native platform. It wasn't just the CPC they did this to - ever wondered why those Sierra adventure games were so much slower on the Amiga? It wasn't the Amiga's hardware that was to blame.

It's understandable why developers would go the 'hardware development system' route. Typically they would develop systems for efficiently producing games on one platform, then look at how easily they could adapt it to other platforms. But with low powered hardware which needed intimate knowledge of poorly documented features and a lot of tricks to get good performance, the ports were bound to be mediocre. Doing the job properly would cost have too much and taken too long - in a market that was constantly changing.

35 years later we have a lot more knowledge, incredibly powerful cross-development platforms, and no pressure to get games out quickly before the market disappears. This is why the CPC is finally getting the treatment it deserves. We always knew it could do better, and now we are proving it!

[Bruce Abbott]

BTW it's not only mediocre ports that might be improved. In 1986 when I transferred the Graphic Adventure Creator from tape to disk, I glanced at its code for filling areas in drawings and saw right away that it could be speeded up. 27 years later I finally published a patch that makes the fill function more than 5 times faster!

[LongLifeA1200]

Originally Posted by lmimmfn

Wont comment on CPC being king...

I don't know either yet and that's because sound is almost as equally important to me. Take for example the game "Extreme": I like from the ZX Spectrum the intro music and the sounds effects from the C64.

BSC looks like he is doing something interesting with audio on the Amstrad CPC that "exploits the volume envelope generator".

The other reason why I can't decide is because of the year these computers are launched. The C64 appears two years earlier than the original Amstrad CPC 464. Worse, the CPC 6128 launches along with the Atari ST. When games exclude earlier versions of the Amstrad CPC and loading from tape, it disqualifies itself from having bettered the C64. I don't mind if the CPC 464 version needs to have more compromises made, as long it is given the same chance, then I'm happy.

Originally Posted by Bruce Abbott

Many 664 owners got upset about the 6128 with its extra 64k internal RAM being released so soon after they had bought their machines, but not me. I unsoldered all the 64k RAM chips and replaced them with 256k chips, then designed a bank switching circuit compatible with the 6128 that could access the entire 256k, to a produce a better machine than the 6128!

That is phenomenal.

[dlfrsilver]

Look at this beta preview of SF2 on CPC :

[ Show youtube player ]

[viddi]

Cool. Thought it was dead....

[Tigerskunk]

So what happened to Vespertino?
2 years since last time something was shown is a long time...