System Specs

[steve]

From the CPC 464 to the 6128plus, these machines offer a range of performance and features that are not common to all systems, so I would like to propose that the systems are divided into 4 categories, and programs may be offered in 4 versions to get the best from the machine it is running on.

CATEGORIES

64k cass.
Distributed on cassette, will optionally transfer to disk if one is detected, will test for plus hardware and use it if found, may contain a simple game to keep you from getting bored while the actual game is still loading from cassette, will not require more than 64k ram but may use extra ram if found.

128k disk.
Expects 128k ram, loads extra data and code from disk as needed, tests for plus hardware to use if found, may use all 180k disk space or more.

6128plus
Written for the 6128plus but might run on a 6mhz CPC, we will expect people to overclock their CPC's if they want to run 6128plus games, so program should offer z80 routines to do the work of the plus hardware, 6128plus will of course use the plus hardware, the program will test for CPC running at 6mhz and will not be expected to run on a 4mhz CPC.

512k cartridge.
Exclusively plus hardware, may expect ram expansion and possibly extra code and data loading from disk.

These categories are the most common configurations.

As a programmer no longer being paid by the hour, would you want to create up to four versions of your program to get the best from the machine it is running on?

[andycadley]

I'm not at all sure what you're trying to accomplish. 64/128/64+/128+ is probably the only definition you really need, with disc only in some cases. Bringing in oddities like a 6Mhz CPC (does such a thing even exist?) is unnecessary. And, in any case, a couple of extra Mhz on the CPU isn't even nearly enough to compensate for the additional hardware functionality included in the plus range.
As for writing 4 different versions of games, ain't going to happen. It requires enough (unpaid) time and effort to do one version. Realistically I think most devs these days should just assume a 128K system is a fair baseline, with or without plus functionality.

[steve]

I'm not at all sure what you're trying to accomplish. 64/128/64+/128+ is probably the only definition you really need, with disc only in some cases.

If you write a program to run on a 464/664/464plus, it will not use the extra memory in a 6128, if it does then it will not run on a 64k machine without additional ram, it is not reasonable to demand that 464 owners buy ram packs which are no longer being made, just so the programmer doesn't have to accommodate 464 owners, the 64k category caters for the 464/664/464plus users and needs to be on cassette.

A 64k program will run on the 6128 but will not use extra memory unless it is programmed to do so, which makes it a 128k program, so you can either wait while a 128k program is loaded from cassette since 464 owners use cassettes, or you need 128k versions to be distributed on disk for the 6128 users.

A 128k disk program that will run on a CPC6128 will not fully utilize the extra time given to the z80 by using the plus hardware in a 6128plus, so IF you want to really push the hardware then you need a third category for the 6128plus, such programs will be too much for the 4mhz z80 in a CPC 6128 but they may run on a CPC 6128 if the speed has been increased to 6mhz, no guarantees, but it might be enough.

If we cannot hope that someday someone will put a 512k program on a cartridge, then we might as well say that the CPC has come as far as it ever will and software will never be any better than it is now.

These categories are only relevant if you want to push the hardware to its limits, if you are happy with lazy Spectrum ports then there is no more to be said.

Bringing in oddities like a 6Mhz CPC (does such a thing even exist?)

it's in the Wiki.

And, in any case, a couple of extra Mhz on the CPU isn't even nearly enough to compensate for the additional hardware functionality included in the plus range.

it may be enough.

As for writing 4 different versions of games, ain't going to happen.

it is optional depending on the needs of the program.

It requires enough (unpaid) time and effort to do one version. Realistically I think most devs these days should just assume a 128K system is a fair baseline, with or without plus functionality.

In other words, ignore 464 owners and let the 6128plus hardware go to waste.

[andycadley]

But you can accomplish all that without creating wierd categories, you just say 'this game needs a 464+' or '64K disc only' or whatever. And I can assure you, as a programmer, that a 6MHz CPU in a standard CPC isn't going to give you the muscle necessary to pixel shift the screen at 50fps with hardware-like sprites. And that's before you think about things like the extra colours and interrupt functionality only present on the plus range.

As far as cartridges go, I'd love to see some 512K carts. I also think it'd be decidely odd to do so without making them compatible with the GX/464+, since the benefits of the extra 64K ram and disc drive of the 6128+ are basically negligable at that point.

[redbox]

As far as cartridges go, I'd love to see some 512K carts. I also think it'd be decidely odd to do so without making them compatible with the GX/464+, since the benefits of the extra 64K ram and disc drive of the 6128+ are basically negligable at that point.

I've always thought this too.  Only draw back is the extra 64kb is RAM where as on a cartridge it would be ROM.  Apart from that, cartridges work easily as well with 128kb as they do 64kb.

[andycadley]

I've always thought this too.  Only draw back is the extra 64kb is RAM where as on a cartridge it would be ROM.  Apart from that, cartridges work easily as well with 128kb as they do 64kb.

You don't generally require all that much ram, since it's really only being used for variables (and the display), rather than storing large amounts of code/static data like a normal tape/disc game.

[steve]

But you can accomplish all that without creating wierd categories, you just say 'this game needs a 464+' or '64K disc only'

Since the introduction of the DDI-1 there have been two categories, cassette and disk, I am merely suggesting that the software be tailored to suit the needs of the machine, i.e, don't try to load a 128k program that expects disks into an unexpanded 464 simply because it came on cassette.
And I am suggesting two new categories for the 6128plus,  if you don't write software that uses the plus hardware to it's fullest, then these two new categories can be ignored.

And I can assure you, as a programmer, that a 6MHz CPU in a standard CPC isn't going to give you the muscle necessary to pixel shift the screen at 50fps with hardware-like sprites. And that's before you think about things like the extra colours and interrupt functionality only present on the plus range.

Obviously a CPC will never display a 4096 colour palette, but the CPC can shift sprites already so a 50% speed increase should help a lot, but if you really do push the 6128plus then the CPC simply will not run it and there is nothing that can be done about it, however, in many cases a 50% increase in speed will be enough.

As far as cartridges go, I'd love to see some 512K carts. I also think it'd be decidely odd to do so without making them compatible with the GX/464+, since the benefits of the extra 64K ram and disc drive of the 6128+ are basically negligable at that point.

As I said, the cartridges will be EXCLUSIVE to the plus range and obviously use the all the hardware features.
Maybe one day there will be a cartridge that will need to access data from disk and use 128k ram or more to process that data, maybe a paint program, database application or music creation program.

Yes, these jobs could be done on a PC, but it would be so much better to make the PLUS do it.

[redbox]

Obviously a CPC will never display a 4096 colour palette

Has already been done 

Yes, these jobs could be done on a PC, but it would be so much better to make the PLUS do it.

I agree.  I know others write PC programs for their development, but when I want to do something with the Plus/CPC in mind, I usually end up writing the utility for the actual Plus[nb]Might just be because I'm crap at PC programming though[/nb].

[Ghost]

4096 on plus... It's easy to make that...


An exemple ? http://www.cpc-power.com/cpcdemos/index.php?page=detail&num=9


@Redbox: i hope you will make great CPC plus demo soon. I want to make gfx for you

[redbox]

@Redbox: i hope you will make great CPC plus demo soon. I want to make gfx for you

Working on it - got an idea, just need to see if I can make it happen 

[steve]

4096 on plus... It's easy to make that...

The CPC only has a palette of 27 colours and will never be able to display 4096 colours, the Amstrad 464plus and 6128plus can display 4096 colours but are not CPCs.

[MacDeath]

The sad thing with the Plus is to have some shitty 64k models...

You can't do anything in case of GX4000... but 464+ and 6128+ actually have the same Motherboard, too bad none of them are really complete...

6128+ lacks the Tape stuff while 464+ lacks a lot of stuff : Ram, Disk...


BTW :
=good little game : 464-664 config can be good enough, but don't expect a thing with lot of content......
=Good great game : don't expect to use anything else but a 6128...(disk + extra Ram)

For the Plus...well...
=Cartridge : better to get them using of course 512K Rom, but 64K is good as it enables GX4000...

=Cartridges+Disks : I wish it were already done... would be great for applications. to me the 6128+ lacks a proper OS...on a 512K cartridge... and a set of good applications : Graphics, Musics...
Concerning games, I can mostly see the potential for a great RPG style game...

=Disks and tapes : tapes are...well... I hate those...
But disks are great with Plus... cheap and reliable, sort of.

[andycadley]

Obviously a CPC will never display a 4096 colour palette, but the CPC can shift sprites already so a 50% speed increase should help a lot, but if you really do push the 6128plus then the CPC simply will not run it and there is nothing that can be done about it, however, in many cases a 50% increase in speed will be enough.

Yes a 6Mhz CPC would be able to push a bit more data around, but it isn't going to compete with 50fps pixel perfect hardware scrolling, which is hardly pushing the plus machines at all. And yet you want to call those '6128plus' games. How does that make any sense at all? Now you might, in the case of a game that needed a 6Mhz CPC, be able to substitute some of the routines with plus enhanced ones to keep it running at full speed on a standard plus, but that would be extremely dependent upon the game. How would your 'categories' describe a game that needs a 6Mhz CPU regardless of whether it's a plus or not?

I just think you're massively overcomplicating something that is actually very simple in an attempt to solve some problem that I don't think actually exists.

[steve]

OK then, forget about trying to run 6128plus software on a CPC 6128.

[redbox]

The CPC only has a palette of 27 colours and will never be able to display 4096 colours, the Amstrad 464plus and 6128plus can display 4096 colours but are not CPCs.

That's why he said "4096 on plus" not "4096 on CPC". 

[steve]

a CPC will never display a 4096 colour palette

Has already been done 

4096 on plus... It's easy to make that...

The CPC only has a palette of 27 colours and will never be able to display 4096 colours, the Amstrad 464plus and 6128plus can display 4096 colours but are not CPCs.

That's why he said "4096 on plus" not "4096 on CPC". 

This sequence of exchanges was about whether a CPC can or will ever display 4096 colours and the answer is no.

[redbox]

This sequence of exchanges was about whether a CPC can or will ever display 4096 colours and the answer is no.

Ok, ok, you win - have a cookie.