Amstrad CPC Core

[PhantombrainM]

Hey Sorgelig,

thank you for the CPC Core. I'm having a lot of fun with this little Core!

Since the last update I've got a strange behaviour. Sometimes when I mount a disk the first time I get "Disc is missing", unknow, retry, abort etc. when typing CAT.

After mounting it again it always works. (Edit: not always but most time). It seems random.

It's the first time from Core 20180711 on and didn't ever happen before.

Anyway, love it!

regards,
PhantombrainM

Edit: I tracked it down. It's a minor bug. If you rename a file in the same folder or add something via FTP while Amstrad Core is in use no files will be mounted anymore. If you CTRL+ALT+DEL then it works again. I think this is a new behaviour?

[Sorgelig]

If you add/delete something from dir while core is running, then you need simply go to upper dir and enter it again to re-read it.
If you don't do this then displayed dir list will be not in sync with real dir.
I know about this issue, but currently have no solution yet. This issue exists since the first MiSTer release.
Consider it as a minor issue as it happens only if you actively add/remove files through network and open them in core at the same time.

This is true for ALL cores, not only for Amstrad.

[PhantombrainM]

You are right Sorgelig. That's war I used to do but it's not working anymore.

Even If i ADD a file its not possible to click on ".." (simply nothing happens).
In previous releases I could go out and back in and everything was okay. Now nothing happens until I reload the Core or sometimes reset.
Haven't investigated further or checked other cores yet. Its also not so important because I'm not changing files all the time.

I was just testing protected stuff, checking and renaming because it was fun and I wanted to test your core changes

All the best,
PhantombrainM

[hubersn]

Also a big "thank you" from me to Sorgelig for the Amstrad CPC core. On MIST, Archie and Amstrad CPC were my main interests and I am very happy to see them both alive and well on the MISTer.

The nice thing about the Amstrad CPC core is that I exactly understand the things Sorgelig writes as "changes" when he improves the core. I have not yet tested the compatibility with the more "interesting" software like recent demos which employ a lot of hardware tricks - I got stuck when "playtesting" Bomb Jack and BMX Simulator, two of my all time favourites...

So again, thanks for porting this core and improving it! If you need suggestions on what extensions you should spend your time, I think the only widely used hardware expansion for the CPC was the dk'tronics RAM extension - 256 KiB "main RAM" and 256 KiB "Silicon Disc". A cool thing would be to provide SYMBiFACE II emulation, but that would only be useful to run SymbOS in a MISTer context.

Have fun
hubersn

[Sorgelig]

Core has 576KB RAM.

[hubersn]

Core has 576KB RAM.

Thanks for the info. Have I missed the option in the core's menu? Ah, found some info on the core's page. It is linked to the CPC6128 model. Strange, but probably not a problem (although I seem to remember there was certain game with a defective detection routine that worked on a plain 6128 but not on a RAM-extended 6128). I will experiment with SymbOS and Discology if everything works as expected.

There would also be a reason to support the CPC464 as a dedicated model, there was (very few!) software that only worked on the 464, including BASIC stuff (because of an annoying bug in the BASIC 1.0 that was 464 exclusive). But I guess building a boot ROM with the 464 ROMs instead of the 664 ROMs it would "just work".

Did you have a specific reason to bundle all the ROMs into one file? Most emulators use separate files.

Thanks
hubersn

[Sorgelig]

If you don't plan to use CPC464 permanently instead of CPC664, then instead of boot rom, you can make expansion rom containing OS&BASIC as explained in readme. And then load it from OSD when you need.

[breiztiger]

Hi

464 as another diff from 6128 and 664, it hasn’t floppy connected physicaly

Some games detect that, also if amsdos is not présent in rom 7

An option to deconnect upd765 can resolve that

Thanks a lot for this core

[Sorgelig]

Then you won't be able to load anything. Well, except the expansion ROMs.
I believe those games are already patched to remove strange check for FDD.

As for disabling AMSDOS, you can create expansion ROM with 16KB of FF.

[breiztiger]

it 's when you make cdt (tape) loading ok

[Sorgelig]

Someone with real Amstrad CPC and ready to run some test would be really helpful!

[breiztiger]

I have 464 664 and 6128

if i can help ...

[Donald1705]

If needed i can help with my cpc 6128.

[Sorgelig]

please test this on real CPC (non-plus model):

plustest.zip

Test No 9: Interrupt Wait test
I need photos from screens of this test.

[Sorgelig]

I also need someone who inderstand how CPC works in detailed level. Like someone from demo scene.
For example there is a demo Backtro - i would like to know how they draw the screen. Original CRTC from Amstrad core has flaws, but this demo works OK. I've ported 6845 from BBC core which basically works more smooth but has some problems like this demo where screen is garbled. So i need hints what to look.

[hubersn]

I also need someone who inderstand how CPC works in detailed level. Like someone from demo scene.
For example there is a demo Backtro - i would like to know how they draw the screen. Original CRTC from Amstrad core has flaws, but this demo works OK. I've ported 6845 from BBC core which basically works more smooth but has some problems like this demo where screen is garbled. So i need hints what to look.

ISTR that Backtro uses the overscan technique, which reprograms the CRTC to make the screen "bigger" which then needs 32 KiB instead of 16 KiB for the screen.

You can find some details about the 6845 registers manipulated here:
http://www.cpcwiki.eu/index.php/Programming:Overscan

I don't have detailed CPC CRTC knowledge I'm afraid and the only knowledgeable CPC coder I know personally and have regular contact with is a fan of software stuff and never touches those strange CRTC registers...

Maybe it helps.
hubersn

[Sorgelig]

According to my exploration Backtro uses dynamic h_displayed to reprogram CRTC in the specific time. Most time it's 48 chars, but at the end if char raw it's 189 chars. So, I've caught original idea - need polish it.

Those well known places as cpcwiki are already explored. They are detailed, unfortunately. Datasheets aren't detailed either because not expected someone will exploit the CRTC work in unusual way. By datasheet there are almost no differences between CRTC types. But really differences are huge when you push the limits

[alexh]

The best person to talk to is Kevin Thacker. He wrote the first "demo quality" emulator for the Amstrad back in the day called A-PC on the Amiga and later Arnold on PC. He's very approachable. I think he created CPCWiki too.

http://www.cpctech.org.uk

[breiztiger]

hi

i have test plustest on my cpc 6128 stock

here are the Screenshot

https://mega.nz/fm/SiJynY4B

as you can see on last Screenshot the cpc freeze on ed codes (test two time)

[hubersn]

The best person to talk to is Kevin Thacker. He wrote the first "demo quality" emulator for the Amstrad back in the day called A-PC on the Amiga and later Arnold on PC. He's very approachable. I think he created CPCWiki too.

Richard Wilson of WinAPE fame is also someone to talk to for the finer details of CPC hardware features. I think WinAPE is currently the most precise emulation available.

http://www.winape.net/

Have fun
hubersn

[Sorgelig]

hi

i have test plustest on my cpc 6128 stock

here are the Screenshot

https://mega.nz/fm/SiJynY4B

as you can see on last Screenshot the cpc freeze on ed codes (test two time)

It seems the link is wrong. It transfers me to my own mega account.

[breiztiger]

https://wetransfer.com/downloads/d7945e ... 148/685225

[Sorgelig]

Thank you!

[PhantombrainM]

Bug report:

Turrican 1 does not work anymore.

Garbled Title Screen and flickering. Doesn't matter if original disc or scene one.

Amstrad_20180711 -> works
Amstrad_20180717 -> not working

RAM, CRTC Settings doesn't change it.

regards,
PhantombrainM

[Sorgelig]

Thanks for report.
I will check