Spectrum Computing

The original Pi1 will work however the author is having great difficulties keeping the first pi supported because of some limitations.
For instance you won't have sound over HDMI.
I think the PI2 is the best option.
It does have sound over HDMI and it's more than capable of running the emulator at full speed. A pi3/3B etc. is a bit overkill for just a spectrum.

Mbwum73 wrote: ↑Thu Jul 30, 2020 5:14 pm I think the PI2 is the best option.
It does have sound over HDMI and it's more than capable of running the emulator at full speed. A pi3/3B etc. is a bit overkill for just a spectrum.

The only one advantage from a better PI is a faster "fast loading".

The HDMI sound support needs more CPU than an ARMv6 based PI have. The Circle library uses a cooperative scheduler and the VC4 needs to be attended so frequently that isn't capable of execute the Spectrum emulation and send the needed sound data to the VC4. And more, in Circle all the interrupts are handled by the CPU-0, so the only one CPU present in first PI models isn't so fast to execute all the needed tasks (the USB handling needs many CPU time, the USB host on the PI is crap).

Anyway, I don't know what to do with ZXBaremulator. Develop a bare-metal emulator is a huge task and the user base is really tiny three years after the first release. Today, the people uses software emulators on PC and the alternative solution is a FPGA based board. Not many people have a PI board and many Pi users aren't interested on the ZX Spectrum. That looks as a dead end, my friend...

I agree.
Simply, time goes on, technology advances and people have more and more choices.
Small board computers are getting cheaper, including fpga multicore solutions, the raspberry pi 4 with latest price reduction and over 3 million units sold, it has already become a far better purchase than the old models.
The Spectrum user base is limited and dispersed, but the Baremulator certainly has its place.
I would just like to get rid of this buzzing sound, which we talked about earlier.
I don't know if you had time to investigate it, I just have this problem on each of my 3 pi models (2, 3, 3+) and I haven't been able to eliminate it, except using the old v2.0 version, which doesn't have a GPIO keyboard support.
However, BM has its advantages, such as precise emulation and the ability to easily connect the Spectrum keyboard and its also free.
I don't know which is the next equivalent variant, I guess ZX-Uno with twice the price than Pi, but also with greater potential for sure.
The new Next kickstarter is already around the corner, so everyone has something to choose for themselves...

Still zxbaremulator is the only cheap alternative with good hdmi support and I can use my ps4 controller with it.

Alternatives? MISTer FPGA is expensive, zxuno doesn't have hdmi and other software emulators require a complete OS resulting in long boot times. The Spectrum next is unavailable and still has a timing problem with HDMI. So maybe there will be a second run, but will they also fix the hdmi problems?

So I hope you consider working on the "easy" parts like that extra keyboard led and maybe a default machine option. I know your audience is small and time is limited, but talking for myself I am a very grateful guy for what you've achieved so far.

Maybe another option is to release the source code so maybe other enthousiast can continue. Unfortunately I'm not a very skilled programmer but maybe someone else is.

Pegaz wrote: ↑Fri Jul 31, 2020 1:33 pm
I would just like to get rid of this buzzing sound, which we talked about earlier.
I don't know if you had time to investigate it, I just have this problem on each of my 3 pi models (2, 3, 3+) and I haven't been able to eliminate it, except using the old v2.0 version, which doesn't have a GPIO keyboard support.
However, BM has its advantages, such as precise emulation and the ability to easily connect the Spectrum keyboard and its also free.
I don't know which is the next equivalent variant, I guess ZX-Uno with twice the price than Pi, but also with greater potential for sure.
The new Next kickstarter is already around the corner, so everyone has something to choose for themselves...

The problem with the buzzing sound is that I can't reproduce it on my TVs. Could be that some TVs aren't happy with the 32 kHz sampling rate I use.

The ZX-Uno is dead. I own one, sleeping in his box. Nobody develops cores for it. Now, you can choose a MiSTer, Mistica or SiDi. But don't exist a FPGA core that his behaviour will be so precise as many software emulators. And nobody have enough motivation to enhance the cores. The most important core for MiSTer is NeoGeo.

The Next isn't for me, for less money I can have a MisTer with 128MB, I can live without his pretty keyboard.

Mbwum73 wrote: ↑Fri Jul 31, 2020 10:26 pm
Maybe another option is to release the source code so maybe other enthousiast can continue. Unfortunately I'm not a very skilled programmer but maybe someone else is.

Some "smart" guys on eBay are selling ZXBaremulator and BMC64. I don't want to get any money from my emulator, but I don't want that another shameless guy get money from it. Create a commercial "ZX-Mini" could be really easy having the source code at hand. So, the only one solution is don't release the sources. That's the sad true.

ZX-Uno is kinda dead, but I thought its ZX core is pretty mature and doesn't really need any further work. It's the same with MiSTer's ZX core. Do you know of any significant differences which would need fixing? We can always open issue ticket and mention it on the forums. Of course, console cores get more attention, but microcomputer's also have a big following.

BM ZX on a Pi is a good idea for sure, since it's a much cheaper option than FPGAs. Does it help with lag though? When I was using ZX emulators on RetroPie + my RPi 3B+ they've felt very laggy.

Just so that you know, the main reason I have a 2012 Pi is because there were a couple on sale in CEX when I looked and I thought I'd buy the one with the case, just to experiment and see what it could do. If there was a "Big Book of Raspberry Pi Projects" published around 2013 that might be useful - but for now, seeing as I've at least made it work with a version of Raspbian from circa 2016 and some bits and pieces I had lying around, and don't intend to go a lot further, I'll explore ZXBaremulator as another option.

So as for the next question:

It is suggested that I need a minimum of 8 GB on the SD card to get even the first version of Raspbian to run properly. I've only got one of those, so that's what I've used for Raspbian. But I also have some 2 GB SD cards sitting idle - would they be OK to run ZXBaremulator from?

TMD2003 wrote: ↑Sat Aug 01, 2020 10:34 am I also have some 2 GB SD cards sitting idle - would they be OK to run ZXBaremulator from?

2 GB is fine for ZX Baremulator.

I have found no lag on either the Bmc64 emulator or the ZxBaremulator , They remind me of when I had the z80 emulator running in dos on the pc, just did what is needed to do and no windoze or operating system in the way.

Just great, Bmc64 allow you to save to a virtual disk , I would love to see tape saving to a virtual tape on the zx or snapshot function to save your game position .
i have included a pic of my 2 machines I resurrected out of a dead shell and a new case. And errr the C64 made out of a old case, these all have direct input to the original keyboards by the interfaces suggested on the website which i lovingly soldered together .

I tend to use the Pi3 a+ as its small and easy to cram in the original shell (and cheaper)









and the bmc64 built

zx81 wrote: ↑Sat Aug 01, 2020 9:11 am

Pegaz wrote: ↑Fri Jul 31, 2020 1:33 pm
I would just like to get rid of this buzzing sound, which we talked about earlier.
I don't know if you had time to investigate it, I just have this problem on each of my 3 pi models (2, 3, 3+) and I haven't been able to eliminate it, except using the old v2.0 version, which doesn't have a GPIO keyboard support.
However, BM has its advantages, such as precise emulation and the ability to easily connect the Spectrum keyboard and its also free.
I don't know which is the next equivalent variant, I guess ZX-Uno with twice the price than Pi, but also with greater potential for sure.
The new Next kickstarter is already around the corner, so everyone has something to choose for themselves...

The problem with the buzzing sound is that I can't reproduce it on my TVs. Could be that some TVs aren't happy with the 32 kHz sampling rate I use.

The ZX-Uno is dead. I own one, sleeping in his box. Nobody develops cores for it. Now, you can choose a MiSTer, Mistica or SiDi. But don't exist a FPGA core that his behaviour will be so precise as many software emulators. And nobody have enough motivation to enhance the cores. The most important core for MiSTer is NeoGeo.

The Next isn't for me, for less money I can have a MisTer with 128MB, I can live without his pretty keyboard.

Interesting, I didn’t know the situation with the zx-uno was so bad, I was just thinking of buying one.
In terms of emulation accuracy, what are the main differences between BM and ZX-Uno Spectrum core ?
Regarding buzzing sound, that remains as the only logical explanation, because I tried everything else (several Pi's, hdmi cables, power supplies) and it's always the same.
Is the sound part from v2.0 (including the sample rate you mention) the same or was it changed later, because I don't have a sound problem with this version.
I don't know much about that MisTer board, just noticed insane prices, say over $ 300.
Where do you find all that, cheaper than Next?
As for releasing source code, you are absolutely right.
There are too many thieves and dishonest people, who can't wait to take advantage of someone else's work.
For home use BM is quite good, as it is now.

I have the same annoyance with people reselling the mags I lovingly scanned, I have hopefully stolen their thunder as I have rescanned most at 600dpi and made them freely available.

I can understand people selling the interface boards for the baremetal emulators as they do take skill and time to make but not the software itself . At a push the complete machine with the software inside of it , but that is contentious with the amount being charged by some .

I have a few spare c64 interface boards as you have to buy a minimum from Pcbway . But would not resell the software.

To be honest I just love tinkering so making the machines keeps me sane in these uncertain times

Mort wrote: ↑Sat Aug 01, 2020 10:48 am I have found no lag on either the Bmc64 emulator or the ZxBaremulator , They remind me of when I had the z80 emulator running in dos on the pc, just did what is needed to do and no windoze or operating system in the way.

I have always loved such dedicated machines.
Recently I adapted my old Toshiba Portege laptop with RealSpectrum emulator and MB02+ interface, as a default.
It performs really great, with support of a real floppy disks and saved me several hundred dollars for MB02.
This old but still great emulator works best in pure DOS, I put it in the autoexec sequence and it boots up very quickly.
The biggest value of this emulator is full support for physical floppies, for almost all important Spectrum formats and interfaces.
It has full read/write support and I use it as an extremely valuable tool.

Problem with lag is that it needs proper measuring, because the differences are pretty subtle. And OS is not the only reason causing it so there definitely still is some.

You can get MiSTer + 32 SDRAM for ~ 170E. This will run 90% of the cores. ZX Uno is about half that price, but only good for ZX (other cores are half baked).

I never realized people steel from you by selling your hard work. In that case don't release the source code. I was only suggesting it because it could help development forward. It is very usable already though and I'm quite happy with it. I just hope you may find time and inspiration to continue the development. Even if the group of users is still small.

By the way... That buzzing sound I hear it too. After every boot for a few seconds. Didn't hear it 2.0 though.

Mbwum73 wrote: ↑Sat Aug 01, 2020 12:45 pmBy the way... That buzzing sound I hear it too. After every boot for a few seconds. Didn't hear it 2.0 though.

Thanks for the confirmation, although it seems minor, this is a pretty annoying problem to me.
Earlier in this thread, I tested in detail the most common ways this issue is triggered.
Obviously it doesn’t happen to everyone, which is the worst case scenario for bugfixes...

Pegaz wrote: ↑Sat Aug 01, 2020 10:55 am

zx81 wrote: ↑Sat Aug 01, 2020 9:11 am The problem with the buzzing sound is that I can't reproduce it on my TVs. Could be that some TVs aren't happy with the 32 kHz sampling rate I use.

The ZX-Uno is dead. I own one, sleeping in his box. Nobody develops cores for it. Now, you can choose a MiSTer, Mistica or SiDi. But don't exist a FPGA core that his behaviour will be so precise as many software emulators. And nobody have enough motivation to enhance the cores. The most important core for MiSTer is NeoGeo.

The Next isn't for me, for less money I can have a MisTer with 128MB, I can live without his pretty keyboard.

Interesting, I didn’t know the situation with the zx-uno was so bad, I was just thinking of buying one.
In terms of emulation accuracy, what are the main differences between BM and ZX-Uno Spectrum core ?
Regarding buzzing sound, that remains as the only logical explanation, because I tried everything else (several Pi's, hdmi cables, power supplies) and it's always the same.
Is the sound part from v2.0 (including the sample rate you mention) the same or was it changed later, because I don't have a sound problem with this version.
I don't know much about that MisTer board, just noticed insane prices, say over $ 300.
Where do you find all that, cheaper than Next?
As for releasing source code, you are absolutely right.
There are too many thieves and dishonest people, who can't wait to take advantage of someone else's work.
For home use BM is quite good, as it is now.

The ZX-Uno's Spectrum 48k core is basically correct, but the contended memory timings is wrong on all cores, all FPGA's I know. The 128k core isn't complete and the FPGA PLL can't generate the needed CPU freq. for the model (is off by 8 kHz). The +2a is the same core than 128k with the +2a ROMS. Anyway, the image quality is very poor, IMHO. Three years ago, could be that ZX-Uno was an option. Today, is obsolete.

All the ZXB versions uses the 32 kHz sampling rate. All my PIs runs correctly (B+, 2, 3, 3B+), so is a hard problem to debug. And change the sampling rate to 44.1 or 48 kHz isn't trivial.

zx81 wrote: ↑Sat Aug 01, 2020 3:27 pm The ZX-Uno's Spectrum 48k core is basically correct, but the contended memory timings is wrong on all cores, all FPGA's I know. The 128k core isn't complete and the FPGA PLL can't generate the needed CPU freq. for the model (is off by 8 kHz). The +2a is the same core than 128k with the +2a ROMS.

How do contended memory timings affect accuracy? Could you give examples of software which does not work becasue of that?

It's the same for the 128K core, if they are meant in regard to MiSTer. I'm interested in perfecting these cores, so can ask questions about it but need some concrete examples of reproducible errors.

zx81 wrote: ↑Sat Aug 01, 2020 3:27 pm Anyway, the image quality is very poor, IMHO.

Both ZX Uno and MiSTer's IQ is 1:1 perfect when compared to my real ZX Spectrums - tried it side by side on CRT TVs. Could you be more specific?

[mention]zx81[/mention]

Just to be sure, I re-tested BM v3.2 today, on all three of my Pi's (2, 3, 3+) with small speakers connected to Pi and without any connection to the TV.
In all three cases, the buzzing sound is still there, which tells me that TV is not the cause of this problem after all.
So I think there is some change somewhere, starting with version v3.0, which is causing this sound issue.
The main “problem” is, that you haven’t experienced that issue and then it’s very hard to detect it.
However, if you get an idea, you can send a test version here, I'm sure some of us will gladly test and give full feedback...

I have sent you the link for the C64 baremetal as this explains a lot . Especially as its from the author, and he also made Baremetal emulators to run from the same sd card for the Pet, Vic and C16.


https://www.youtube.com/watch?v=wTCKtOAm9Uo

Well, it's working, even if I'm limited to using composite video (as I don't have any external speakers that aren't being used for something else, which I'd need if using HDMI). Marvellous! I will test it further, soon enough.

I might also need to not use a Mac keyboard, seeing as it doesn't have a Break key on it...

akeley wrote: ↑Sat Aug 01, 2020 3:44 pm

zx81 wrote: ↑Sat Aug 01, 2020 3:27 pm The ZX-Uno's Spectrum 48k core is basically correct, but the contended memory timings is wrong on all cores, all FPGA's I know. The 128k core isn't complete and the FPGA PLL can't generate the needed CPU freq. for the model (is off by 8 kHz). The +2a is the same core than 128k with the +2a ROMS.

How do contended memory timings affect accuracy? Could you give examples of software which does not work becasue of that?

It's the same for the 128K core, if they are meant in regard to MiSTer. I'm interested in perfecting these cores, so can ask questions about it but need some concrete examples of reproducible errors.

zx81 wrote: ↑Sat Aug 01, 2020 3:27 pm Anyway, the image quality is very poor, IMHO.

Both ZX Uno and MiSTer's IQ is 1:1 perfect when compared to my real ZX Spectrums - tried it side by side on CRT TVs. Could you be more specific?

The IR_Contention test don't runs correctly on any FPGA (excluded the Next, I know nothing about it). Many 128k cores runs at a lower speed freq (the ZX-Uno runs at 3.5 Mhz, not 3.5469 Mhz). Many demos (Paralactika, Mescaline, Tiratok, etc) runs bad or fails badly. I own a ZX-Uno, and I know the status on others FPGAs by users, not by my own tests. The Spectrum 48k implementation is a bit better, but far from perfect, IMHO.

zx81 wrote: ↑Sat Aug 01, 2020 9:11 am

Pegaz wrote: ↑Fri Jul 31, 2020 1:33 pm
I would just like to get rid of this buzzing sound, which we talked about earlier.
I don't know if you had time to investigate it, I just have this problem on each of my 3 pi models (2, 3, 3+) and I haven't been able to eliminate it, except using the old v2.0 version, which doesn't have a GPIO keyboard support.
However, BM has its advantages, such as precise emulation and the ability to easily connect the Spectrum keyboard and its also free.
I don't know which is the next equivalent variant, I guess ZX-Uno with twice the price than Pi, but also with greater potential for sure.
The new Next kickstarter is already around the corner, so everyone has something to choose for themselves...

The problem with the buzzing sound is that I can't reproduce it on my TVs. Could be that some TVs aren't happy with the 32 kHz sampling rate I use.

The ZX-Uno is dead. I own one, sleeping in his box. Nobody develops cores for it. Now, you can choose a MiSTer, Mistica or SiDi. But don't exist a FPGA core that his behaviour will be so precise as many software emulators. And nobody have enough motivation to enhance the cores. The most important core for MiSTer is NeoGeo.

The Next isn't for me, for less money I can have a MisTer with 128MB, I can live without his pretty keyboard.

Pegaz, not sure if I'm hearing the same buzzing sound as you, but I have a feeling it's something different. It's more of a few clicks that I sometimes hear after loading a tape. In some cases the virtual tape doesn't stop after the game has loaded and I have to press F8 to stop the tape. This doesn't bother me because you would have to stop a real tape connected to a real Spectrum anyway.
This was more prevalent on my Pi 2 than it is on the Pi 3 B+ that I'm using now. In fact now it so rarely happens that I don't notice it.

I agree with zx81 on halting development although I am admittedly disappointed. At the same time I do feel ZXBaremulator is "complete" in it's current state and offers a great and true to life emulation experience. I plan to continue using it as my main emulator.

TMD2003 wrote: ↑Sat Aug 01, 2020 6:27 pm Well, it's working, even if I'm limited to using composite video (as I don't have any external speakers that aren't being used for something else, which I'd need if using HDMI). Marvellous! I will test it further, soon enough.

I might also need to not use a Mac keyboard, seeing as it doesn't have a Break key on it...

I got lucky on a pair of laptop speakers that plug straight into the Pi's 3.5 in socket, with the USB plugging into the Pi for power. They sound great on ZXBaremulator and are solidly constructed and can easily clip onto a small display. It also has volume control. I paid $15 on Amazon.
Here's the link if you're curious:
https://www.amazon.com/gp/product/B01EH ... UTF8&psc=1

[mention]cmal[/mention]

Unfortunately, it’s a little worse than that.
In my case, it's an unpleasant buzzing sound of about five seconds each time I enter the F1 menu and go back to the emulation.
I have described this in more detail on page 3, in this thread.