Amstrad CPC Core

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Amstrad CPC Core

Postby soydemadrid » Sun May 10, 2020 8:00 pm

Today I tried the Amstrad CPC core from Victor Trucco's repo here:

I just wanted to start a thread here just to say it worked really well. Currently it seems to only use the VGA port and external PS/2 keyboard. Also reset doesn't work.

Other than that it is working nicely for the .dsk images provided in the file he provides.

Thanks for the great work Victor.

I hope you get chance to work on integrating the CPC to work with the next keyboard, hdmi and have more features.

Also just some quick instructions to help others:

To get the cpc core to work you have to add the Amstrad CPC6128.bit file to your /machines/cpc/ folder and rename it CORE.BIT

Then extract the provided to the root of your Next SD Card so that the game .dsk images and the ROM files are on there with all your normal Next files.

Then slow power reset the Next and hold C on boot to get the Alternative Cores menu, then you can add the CPC core to a free slot there.

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Re: Amstrad CPC Core

Postby Odin » Tue Jul 20, 2021 9:56 am

i can't get the Amstrad CPC core working. I did exactly what you described here (including configuring the Alternative Cores menu entry) but on one monitor (connected via VGA) i get no picture at all and on another monitor i get a pattern of grey and black lines but no blue background with yellow text as supposed to be. I put the ROM files from the in the /machines/cpc/ folder and also in the root folder of my Next SD card.

After that not working i also created a core.cfg file in the /machines/cpc/ folder with "resource=OS6128.ROM,0" and "resource=BASIC1-1.ROM,1" (and so on) but this also didn't work. I think the Amstrad's OS Rom is at $0000 and Basic at $4000, so i took pages 0 and 1 for OS and BASIC. The Amsdos will be paged in as needed (also at $4000 i think).

Can anyone tell me what's wrong? Thanks a lot!

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Re: Amstrad CPC Core

Postby Odin » Wed Jul 21, 2021 1:35 pm

Maybe it has to do with the used SD card size and format. I got the MSX core working with an 1 GB SD card with FAT (FAT16) format with 16 kb block size. I have read somewhere that the FPGAmstrad needs a 4 GB SD card formatted with FAT32 and 4096 bytes block size, but this didn't work.

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Re: Amstrad CPC Core

Postby chris » Mon Jul 26, 2021 11:16 am

Are you using the latest firmware from the repo? Most alternative cores don't work with this as the memory layout has changed and the cores need modifying to work again. Unfortunately this was brought in around a year ago and no sign of an official release yet, which is when the cores are likely to be modified.

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Re: Amstrad CPC Core

Postby JoelKind » Tue Jul 27, 2021 9:53 am



YES! It work's, JUST! You say.

I have try it too. :-)

But copy the ROM's and .dsk-Files too,
to root Dir of the SD_Card, and it RUNS!

RESET! Can be done by pressing PageUP Button, nice! :-)

Now I have 2in1 8-Bit Computer, and of cause,
with more Cores! A lot of more!!! :-)))

Maybe ALL! Of the 8-Bit Computer, ever MADE! Why not!?
BUT! I'am NOT! A Ingenieur, to DO! That, sorry.

And YOU! Have of cause, MODERN! Hardware too,
with more SPEED! And RAM/ROM, then ever before,

What else?

And I hope too, with Rpi-Zero POWER! Maybe LINUX! Too,
with FULL! Support for any USB-Device, like Mice, Keyboards,
PLEASE! With RGB_Light too, over PS/2 my (RGB_Color)
USB/PS/2 Adapter keyboard DON'T ! Work, I think, to much POWER! (5V/1A) need.
And HDMI second Monitor output, or like I say, LINUX too,

Then I have, 3in1, even BETTER! For me. :-)))

And NO! I don't have a ORIGINAL ZX-Next,
But a N-GO ZX-Next, almost the same. :-)))

Like I have say it, I LIKE! My "New" ZX-Next,
and my FIRST! Home computer was a CPC6128.

=> ATTENTION!!!!! Help NEED!!!!!!!! <=
=> PLEASE! Make every keyboard WORK! <=
=> LIKE! Windows DO! (UK or US or DE or FR...)
=> Keyboard LAYOUT! Switch over "Driver", maybe or BIOS(ROM) !!!
=> And over USB! Too (Rpi_Zero) OK!? Understand me!?!

And what I have learned, from emulators and
Other 8-Bit computers, that the most PROBLEM!
Is the KEYBOARD! By typing words! And I get
"wrong" or other letter, for each diffrent Computer,
=> PLEASE! Correct THIS! Very IMPORTANT! For "me" (US!!!) Ok???

And the other Problem is, to few MANUALS!!!
THIS! Is a very BIG! Problem too. YES! For sure.

Or YOU! Want to make programming Computer
MAYBE! A "big" SECRET!? => VERY! STUPID!!!! For me.

Everbody HAVE! To LEARN! Everything!!!!!!!!!

And the whole LIFE! Of a HUMAN! Is just LIKE!

Three HOURS! Yes, ONLY! Like 3h, understand me???

JUST! Read the HOLY! Bible, then YOU! Know,
That's ALL! I have to say, about FAITH! => Finish, I HAVE! Yes, Amen.

=> PLEASE! Don't hate me NOW! Because I Have SAY!
=> Something about JESUS! The LORD! Amen, YES! Amen.
=> BUT! For me, the BEST! Advice to every creatures, YES! For sure, END!!!

Hm, I hope, some HUMANS! Will program

NOW! "Great" SOFTWARE! For the ZX-NEXT
With more WISDOM! And PEACE! And Freedom, YES! Amen, END!

That's ALL! I have to SAY! For NOW!

GREETINGS! From Germany

Joel Kind
(Krasnica Stepanovic)

PS: Have FUN! And LOVE! The GOOD! => Always,
But NEVER! Ever the BAD! Or wrong "THINGS!" Amen.

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Re: Amstrad CPC Core

Postby Odin » Wed Jul 28, 2021 8:11 am

thanks for your answers. I'm using the Next firmware "sn-complete-v.1.3.2" (which is the latest i guess) and i have put all ROMs and DSK files in the root of the SD card but it still doesn't work. What SD card size (in GB) and format do you use? FAT, FAT32 and which block size?

As chris said the cause is a changed memory layout. Is it difficult to adapt and re-compile a core? I have never done VHDL, is it difficult?


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Re: Amstrad CPC Core

Postby Odin » Wed Jul 28, 2021 9:11 am

In the "nextzxos-changelog.txt" there is an entry for "v2.05 2020-02-20": "Major internal reorganisation to free up space for fixes and new features." - i guess you mean that, chris?

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Re: Amstrad CPC Core

Postby JoelKind » Wed Jul 28, 2021 9:14 am

I have 16GB SD card, and "normal" format, FAT32, block size, by default from Win10.

READ! The Manual from ZX-Next, or from the DOCS folder, how to get work a core!

If you DO! Like the manual, it should WORK!


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Re: Amstrad CPC Core

Postby Odin » Wed Jul 28, 2021 12:18 pm

Ok thanks i will try!

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Re: Amstrad CPC Core

Postby Alcoholics Anonymous » Thu Jul 29, 2021 2:25 am

The change occurred in version 3.01.06 of the zx next core:

MULTI-CORE : Physical SRAM address pins A10 and A18 were swapped to place FPGA configuration pin HSWAPEN on A18. This restricts SRAM corruption to odd multiples of 256K between core boots. Core sram initialization can safely be done in even multiples of 256K and the initialization program running in standard spectrum memory does not reside in the safe areas so that it does not reduce the amount of initialized sram available to cores. Nextreg 0x04 ram bank has been expanded to seven bits from five so that the entire 2MB of memory is reachable for the sram initializer, making half the zx next's memory accessible to initialization for cores.

There is up to 2MB of ram memory in the zx next. The zx next can initialize that ram with whatever is needed by a core including rom data (amstrad cpc in this case) and then the fpga loads the amstrad hardware with sram contents intact and that will block off parts of the sram as read-only to make the rom portion of the system.

Modifications to the older cores to make it work with the current zx next cores is fairly simple, amounting to swapping a couple of bits around on the address sent out to sram. As far as I know, only the BBC cores have been updated as it was the BBC core designer who identified the sram corruption issue.

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