info about asic of GX4000

[emilen72]

hi to all, i have a simply question but don't find a clear response... can you tell me if the asic chip inside th GX4000 include the drive interface? If not how can I connect a diskdrive to the GX4000?


many thanks to all

[TotO]

No, the Floppy Disk Controller was another chip.
Sure, you have better to buy a 6128+.

[steve]

If you cannot find a 6128+ then there were instructions printed in one of the amstrad magazines showing how to install the components necessary to add a disk drive to a 464+.
There were other articles showing how to add a tape interface to a 6128+ and add 64KB extra ram to a 464+.
This was possible because both the 464+ and the 6128+ use the same PCB with fewer components fitted according to whether it was a 464+ or 6128+.

[TFM]

Any links for that?

[MiguelSky]

It was at Craigster page Amstech Services, but it is not online anymore...

[steve]

I do not have the issues to hand now, but looking at the front pages in the wiki, I think it might have been amstrad action mar-may 1993, but that is pure guesswork.

[Cpcmaniaco]

http://members.multimania.co.uk/Craigster/

http://members.multimania.co.uk/Craigster/Craigster/464plusDISC.html

[Spirantho]

While I'm by no means an expert on Amstrad stuff, I'm pretty sure that to hack a GX4000 into a 6128+ is a very tough job, as some parts of it like the keyboard aren't connected anywhere, they're grounded (I think). And if you can't use a keyboard, you'll find it difficult to use BASIC to load from disc.


Fraid you really need a proper 6128 I think.  You can indeed hack a 464 plus though too.

[steve]

If you search this site you will see that Badstar has converted a gx4000 to a computer, maybe he will respond and tell just how hard it was to do.

There are a couple of threads here which detail some of the difficulties.

[emilen72]

ok I now have the right scenario... many thanks to all

[TFM]

http://members.multimania.co.uk/Craigster/

http://members.multimania.co.uk/Craigster/Craigster/464plusDISC.html

Thanks' a lot!!!

[MiguelSky]

http://members.multimania.co.uk/Craigster/

http://members.multimania.co.uk/Craigster/Craigster/464plusDISC.html

Thanks, Rafa. I though we missed this page for ever Btw, the list of the components for the Disk Drive for the 464 is missing but I have it overthere...

[Badstarr]

Hi all, just noticed this thread so I thought I would chime in. Well as far as me modding the GX4000 to a full CPC I have a nice tidied up version at the minute with keyboard attached and a Basic/Burnin Rubber cart basically the project is 85% complete but I've been a little side tracked recently with other stuff (mostly car related lol). I have been having a few problems with the disc interface. It seems to work randomly, or sometimes not at all hence there is no YouTube video of the GX4000 loading from disc as yet, just some bugs to iron out I guess, I'll get back to it next week hopefully.


Anyway as for what you need to do to make a GX4000 into a CPC it can be a bit of a headache: You will need a keyboard from a preferably dead CPC, you will need to solder quite a few wires from the ASIC and the AY Sound Generator. That takes care of the Keyboard. Then you will most likely want to solder in a couple of RAM ICs to bring the memory up to 128kb. This will involve more soldering to the ASIC. There are a couple more bits to solder on the ASIC to make it work as a CPC these thankfully are fairly easy. Now building and adding your own disk interface is relatively straight forward provided you can follow the CPC 6128 Plus schematics on the main Wiki, and you can find the correct Data Separator and Floppy Disk Controller ICs. However you will need to solder around 9-10 wires to the ASIC and a few more to the Z80, this is all before you even add an expansion port or even a printer port if you want them. Also right now, I think that the random functionality of my disk interface may mean that I have to re-solder some of the connections I currently have on the Z80 to the ASIC instead (this is just a hunch really). There are a few capacitors and resistors to solder in and some NAND GATEs and a Hex Invertor IC that are use in the disc interface that may take some effort to track down.


Phew...! Anyway, I wouldn't want to put you off attempting to convert your GX4000, there is a lot of work involved and some fiddly soldering, you need to take your time with it. If you have never soldered before, I wouldn't recommend this project, it would be better to try and track down a 464 Plus and solder in the components needed to make it into a disc capable machine as its a lot more straight forward. There is a good guide on how to do this in Amstrad Action Issue No. 91. There should be a PDF copy floating around if you google for it.


If your solder skills are up to the task then you can find most of the info you need in the Cranium's guide How To Make a Real Plus Out of a GX-4000! However, in this guide, the idea is that you use a DDI-1 interface via the expansion port to get disk access. If you have one of these then you are good to go. If not then you can build your own based on the schematics on the wiki or alternatively wait until I have mine all up and running properly and follow the guide I will be writing. Should be fairly soon fingers crossed! 

[TFM]

Good luck!!!