Games behaving differently on the Next

[TheSMoG]

I connect via Scart, the games work.

And that's exactly what happens with the Next as well.

I connect my Next to my TV via HDMI, the games don’t work. I don’t see how that’s even comparable?

It's not comparable which is the point of this entire conversation. Comparing Apples to Apples point for point the Next does exactly what your 2b does. And please remember if you somehow could time your 2b to 60Hz, these games wouldn't work while they will on the Next

If you read above (and I'll sincerely appreciate it if you do) you'll see that even for something that the Spectrum was never designed to do, there is a solution with the Next. It works with minimum involvement for MOST games but for special games with precision timing effects you need something a bit different if you wish to use an HDMI display and that's a core without the extra Next features but with a full frame buffer for HDMI displays. And as a matter of fact in the extra cores repository there is RIGHT NOW a core that does exactly what you wish. So there's no argument point here. The only argument that can be made is that it's not exactly plug-and-play easy without some typing. And it's a valid argument. But as I said we're working on it. And the answer to all the games that may have had some issues is as always: We'll fix them and we have.

Pardon my ignorance, can I ask what your involvement in the Next team is?

I wrote the manual as stated above.

[TheSMoG]

When I get my VGA cable I reckon I'll have exactly what I'm after. Seriously, I'm "on-side" with this.

As mentioned previously there is a core RIGHT NOW that does exactly what you want and it's being enhanced as we speak. Go to https://gitlab.com/victor.trucco/zx-spe ... ster/Cores to get it. An older version is in the System/Next (TBBLUE) repo and a "official" one is being worked on with full bells and whistles

[Alcoholics Anonymous]

But if the Next is more compatible than those extended variants, why is it I can play the games mentioned in this thread as not working correctly on the Next perfectly fine on my Spectrum +2b with DivMMC, which is notorious for compatibility issues?

Please make sure these things are reported to the team directly as they may not be seen if they are only reported in various forums. The problem is going to be in how the snapshot is loaded rather than any compatibility issue and I will make sure Garry knows about it.

Like it’s been said in this thread, the disappointing thing is that the response seems to be very defensive/argumentative instead of admitting there’s an issue and trying to resolve it. All I wanted was a Spectrum that supported HDMI, played games from SD card and was compatible with the Spectrum’s library. All of those things were promised in the Kickstarter and it would be nice knowing that if a list of incompatible games were published - even if it was over HDMI - the response would be “we’ll fix it” instead of trying to put the blame on the people who actually funded making the Next.

It goes both ways. For example, this HDMI issue has been widely discussed for a year and I have personally made sure people were aware of it whenever they asked about HDMI in discussions I have seen, which must have been dozens of times. It's also been widely discussed that the Next hardware is not finished (the hope is to finish for the second kickstarter) and that this HDMI issue is on the list to be tackled. So when you say that no one's admitting a problem, it's a true wtf moment for me and others

As far as what the KS promised, back then the pi was going to deliver hdmi video. The pi would be operating in the same way as the zxhd does for the spectrum. That's no longer possible as you'd need a full on emulator to generate Next video and a pi zero is not up to it. However, the Next can do something else and that is deliver its own digital RGB signal to the pi for processing. Things have moved far since the KS and using the pi as an hdmi solution would hurt the usefulness of the pi as a co-processor so it's something we don't really want to do.

I think the same way, but instead of getting an answer to that question, we get tons of technical essays on why hdmi is a bad boy.
Someone had to do a reality check first and not promise the HDMI feature at all, if it didn't work properly.
Or maybe we just expect too much from people, who haven't been able to fix the Next keyboard for three years.
Fortunately, we still have the right to be disappointed, until further notice.

You got a technical answer so that it can help you understand the problem and explain why VGA / RGB works and HDMI does not.

I'm going to take this opportunity to undo a lot of falsehoods that people like to repeat:

1. The ZX Next project is not related to the UNO project which can be seen by anyone who looks at the fpga source code. When Victor transitioned from an Altera part to a Xilinx part (due to cost advantage), Antonio was a great help in getting him started. The pal timing module (that generates spectrum video timing) was taken from the UNO, as is allowed by the open source license, and due to bugs in this module, some display glitches that the UNO had were also evident in early videos of the Next in operation. From this, the UNO developers concluded everything was copied and withdrew their source code from being open. They had never seen the Next's source code and had no evidence that anything was copied.

2. The Radastan mode on the UNO was incorporated as lo-res in the Next. There is a credit in the source code that acknowledges this. Nothing was copied -- it is another implementation. It was deemed a useful feature and like many other useful features (divmmc, multiface, soundrive, turbosound, etc) it became part of the Next's design. It was not deliberately made incompatible. The lo-res mode was under-specced for the Next which has an 8-bit palette so it was extended to 8-bits per pixel initially. Since then lo-res in 4-bits, like Radastan, was added because it makes sense in the Next design. The scrolling that the UNO added to Radastan does not make sense in the Next design so the Next implementation scrolls that layer like every other of its layers. The Next goes much further in its display hardware and some of the things that were done with lo-res on the UNO just don't make sense in the Next context.

3. ULA+ was initially in the Next. However, it too is under-specced as the Next has 256-entry palettes and ULA+ can only do 64 entries. So another method was sought which turned into ULANext. Due to particular political nastiness concerning ULA+, it was removed for a while. It returned recently when public permission was given to put it in.

This dig:

Or maybe we just expect too much from people, who haven't been able to fix the Next keyboard for three years.

When you run a KS there is a fixed amount of funds available. If you run out of money, the project is dead: see Vega+. It was not known if it would be affordable to use the solution that eventually made it into the Next until the end when production was about to start.

The keyboard was envisioned as a 48k replacement keyboard. As such it was designed for the 8x5 membrane. Board compatibility with the 48k was also seen as a backup in case something went wrong with the case. The double layer membrane was found to be unacceptable as expectations for keyboards are higher in the modern day than back in 1982. So a single layer was attempted with the keyboard manufacturer confident that they could produce something that delivered keypress for two keys (a single compound key) within a reasonable time difference. That turned out not to be the case in the time given them. The keyboard manufacture was handled by a reputable manufacturer with many products in the marketplace. They have much more experience than Pegaz or any other back-seat designers in making keyboards.

The three year wait was not due solely to the keyboard. There were many other contributors, principally the loss of the first mold manufacturer who just decided one day they weren't going to do it anymore.

[DouglasReynholm]

"When Victor transitioned from an Altera part to a Xilinx part (due to cost advantage)"

Always Xilinx' M.O.

Forever buying business/projects from us back in the day by simply undercutting and not necessarily having the better technology.

I'm really not bitter about it.

[toot_toot]

I connect via Scart, the games work.

And that's exactly what happens with the Next as well.

I connect my Next to my TV via HDMI, the games don’t work. I don’t see how that’s even comparable?

It's not comparable which is the point of this entire conversation. Comparing Apples to Apples point for point the Next does exactly what your 2b does. And please remember if you somehow could time your 2b to 60Hz, these games wouldn't work while they will on the Next

My simple point of "I connect my Spectrum +2 to a TV via the two video outputs and the games work, but when I connect my Next to a TV with one of the supported TV outputs, HDMI, some games don't work" is now answered with an additional technical argument of "but the Next is better because of features". Personally, I don't care if the Next does 60Hz. I don't care if it has Timex or Pentagon support. I just wanted it to support the Spectrum library over HDMI as was stated in the Kickstarter Campaign. That was the big seller for me over just using a standard Spectrum. It was a reason to believe the Next was future proofed over my +2 because HDMI is the current standard going forward. Not VGA. I don't expect there will be many TVs with VGA in 10 years time, but they'll still have HDMI.

If you read above (and I'll sincerely appreciate it if you do) you'll see that even for something that the Spectrum was never designed to do, there is a solution with the Next. It works with minimum involvement for MOST games but for special games with precision timing effects you need something a bit different if you wish to use an HDMI display and that's a core without the extra Next features but with a full frame buffer for HDMI displays. And as a matter of fact in the extra cores repository there is RIGHT NOW a core that does exactly what you wish. So there's no argument point here. The only argument that can be made is that it's not exactly plug-and-play easy without some typing. And it's a valid argument. But as I said we're working on it. And the answer to all the games that may have had some issues is as always: We'll fix them and we have.

You've said there is no argument point here because there's a solution RIGHT NOW for the HDMI problem. But the solution involves compromises which involves installing a core that a) isn't easy for a non-technical user - which I'm sure will be eventually addressed b) is stated on the site as "Cores "almost" ready too use" which I'm sure are safe, but I'm not going to risk it until it's 100% official and more importantly c) removes "the extra Next features". So to get a Next that's "fully compatible" with software over HDMI, the solution actually removes some of the other promised features. I'm sure there's very technical reasons as to why this has to be done, but it's disappointing that the response doesn't acknowledge that compromises are being made in order to deliver what I'd imagine many feel is basic functionality of the Next, a fully supported library over HDMI. Basic functionality that was promised in the Kickstarter and as I said above, with TVs unlikely to have VGA support in the future, that's the biggest reason to get the Next fully working over HDMI.

How you've answered my post really makes me feel why there's negative feeling towards the "official" response on issues with the Next. This thread has highlighted issues with games that currently don't behave as expected on the Next. People are disappointed with the HDMI support not being as originally promised. But it feels like the whole issue of HDMI support has a response of there's a solution RIGHT NOW but involves a solution that is not just highly technical, it isn't in the official distribution and removes other features.

I do really appreciate all the work the Next team have put into it and there seems to be a feeling from the Next team that the HDMI issues are widely known, but this topic shows that clearly isn't the case and it's still a thorny issue. It would be nice to have this topic listing games that aren't currently supported with the standard core install, including HDMI issues. As a Next owner, I'd be more than happy to put up some games that aren't working correctly, although it will have the caveat of them going via HDMI as I have no other option. Maybe the Next team could take that list of games and use that list to make improvements to the Next and we'll all be happy.

[akeley]

There is a lot of info in this thread already but it might get lost amidst our rambles and bickerings, and also some of it is a bit too in-depth and technical for mere mortals. It'd be nice to see it collected in one place and in concise form.

Some questions then:
-is there any sort of Next wiki we could put this info in, or read about it already?
-what are the current HDMI compatibility problems/solutions?
-what are some other current compatibility problems/solutions?
-which games/soft are affected?

No takers, ok. I guess it's easier to just turtle up and go on long rambles, using some completely irrelevant tangents, often in response to imaginary slights, and using a snarky/patronizing tone. There seems to be some psychological effect present in relation to all these retro-projects, which makes otherwise reasonable people to behave like cult members, who will perceive even a simplest query as an attack on their idol.

I also do not like the tone of this thread, for other reasons than Mr Reynholm perhaps, so I'll bow out now. I'll get the Next most likely anyway - because like I've always said (and still think) it is an amazing device - but I'll make sure to steer clear of conversations related to it.

[toot_toot]

There is a lot of info in this thread already but it might get lost amidst our rambles and bickerings, and also some of it is a bit too in-depth and technical for mere mortals. It'd be nice to see it collected in one place and in concise form.

Some questions then:
-is there any sort of Next wiki we could put this info in, or read about it already?
-what are the current HDMI compatibility problems/solutions?
-what are some other current compatibility problems/solutions?
-which games/soft are affected?

No takers, ok. I guess it's easier to just turtle up and go on long rambles, using some completely irrelevant tangents, often in response to imaginary slights, and using a snarky/patronizing tone. There seems to be some psychological effect present in relation to all these retro-projects, which makes otherwise reasonable people to behave like cult members, who will perceive even a simplest query as an attack on their idol.

I also do not like the tone of this thread, for other reasons than Mr Reynholm perhaps, so I'll bow out now. I'll get the Next most likely anyway - because like I've always said (and still think) it is an amazing device - but I'll make sure to steer clear of conversations related to it.

Unfortunately I don't think there's a Next wiki listing the games that have differences, which is probably why this thread was started!

But from my own personal experience, I can maybe give you some information.

When it comes to games over HDMI, the big problem is Nirvana+ games which have mixed results on the Next. Some games are still playable but the graphics aren't great. Some games are unplayable because the graphics are so badly corrupted or the graphics affect the gameplay.

I've also experienced games that have a garbled status area on the screen, but I'm not sure if this is down to the individual snapshot. An example is Imagine's Ping Pong, which works fine on my +2b but has a garbled status area and crowd when playing it on the Next. The game is still playable, however, a different snapshot seems to work fine on the Next.

Some games suffer from eventual slowdown which are fixed if you carry out a soft reset on the Next, I mentioned Zynaps and Exolon earlier. Again, I don't know if this is down to the snapshot or if it's something else.

Football Manager Revisited 2018 displays a "Nonsense in Basic" error when you press a key to start, the snapshot works fine on my +2b. I can't find a working snapshot and there isn't a tap file to see if the problem is fixed by selecting a specific machine from the Next menu.

There are sometimes issues with just loading a snapshot and the game itself doesn't work typically freezing on the main screen. This could be down to a bad snapshot, but the same image typically works on my +2b.

These are all from memory but like I said, I'd be happy to do a bit of work in building a list of issues and post them on here if it would help.

[Spud]

Just a side note, anyone who is sufficiently disappointed with their Next should feel absolutely free to sell it to me at cost value

[Lethargeek]

I've also experienced games that have a garbled status area on the screen, but I'm not sure if this is down to the individual snapshot. An example is Imagine's Ping Pong, which works fine on my +2b but has a garbled status area and crowd when playing it on the Next. The game is still playable, however, a different snapshot seems to work fine on the Next.

Some games suffer from eventual slowdown which are fixed if you carry out a soft reset on the Next, I mentioned Zynaps and Exolon earlier. Again, I don't know if this is down to the snapshot or if it's something else.

Football Manager Revisited 2018 displays a "Nonsense in Basic" error when you press a key to start, the snapshot works fine on my +2b. I can't find a working snapshot and there isn't a tap file to see if the problem is fixed by selecting a specific machine from the Next menu.

There are sometimes issues with just loading a snapshot and the game itself doesn't work typically freezing on the main screen. This could be down to a bad snapshot, but the same image typically works on my +2b.

could you please PM me links to these problem snapshots? (no relation to Next, i just want to try in my emulator)

[TheSMoG]

Some questions then:
-is there any sort of Next wiki we could put this info in, or read about it already?
-what are the current HDMI compatibility problems/solutions?
-what are some other current compatibility problems/solutions?
-which games/soft are affected?

No takers, ok. I guess it's easier to just turtle up and go on long rambles, using some completely irrelevant tangents, often in response to imaginary slights, and using a snarky/patronizing tone. There seems to be some psychological effect present in relation to all these retro-projects, which makes otherwise reasonable people to behave like cult members, who will perceive even a simplest query as an attack on their idol.

Sorry I missed this amidst all the noise. The official wiki is at: https://wiki.specnext.dev
There is a section under Refresh Rates which I'll make sure is expanded and the issue discussed.
As for a games list, it's a generic issue affecting a whole class of programs (see elsewhere) so if one is fixed then ALL are fixed. Individual issues with individual games need to be reported to the team (via the official forum, the FB official group and System/Next-TBBLUE git repository Issue reporting) and they're usually tackled in the next version of the distribution as these are usually software problems and not hardware problems.

I also do not like the tone of this thread, for other reasons than Mr Reynholm perhaps, so I'll bow out now. I'll get the Next most likely anyway - because like I've always said (and still think) it is an amazing device - but I'll make sure to steer clear of conversations related to it.

Conversations tend to get heated when you've got clashing philosophies but that's the nature of the web sadly. As for getting a Next since KS2 hasn't started yet, there's an option in the ZX DOS hardware with an extra "Next specific" hat provided by Antonio Villena and a downloadable Next core that follows the developments of the (open source) Next core and thus it's a complete Next minus RTC/PI/ESP/HDMI

[TheSMoG]

Some games suffer from eventual slowdown which are fixed if you carry out a soft reset on the Next, I mentioned Zynaps and Exolon earlier. Again, I don't know if this is down to the snapshot or if it's something else.

This was covered earlier in the thread.

Football Manager Revisited 2018 displays a "Nonsense in Basic" error when you press a key to start, the snapshot works fine on my +2b. I can't find a working snapshot and there isn't a tap file to see if the problem is fixed by selecting a specific machine from the Next menu.

I believe this issue has been resolved in the latest distribution (currently git only) but I'll have a look shortly

There are sometimes issues with just loading a snapshot and the game itself doesn't work typically freezing on the main screen. This could be down to a bad snapshot, but the same image typically works on my +2b.

Such issues may require user interaction via the loader module options. It's most likely down to a feature of the next clashing with badly written software that (usually but not always) sends OUTs to wide range of ports; something that requires disabling of hardware not present in your machine (ergo it wouldn't have any effect there). The suggested (in the FAQ) solution is to try the options in the loader module but if that doesn't work, submit the game (and a copy of it) to the team via the git issues section (registration required) in order to be looked at. Here I'll also suggest that a wiki page with the appropriate settings for said game will be recorded by the user once he/she finds the proper setting for this game. It's a wiki AND a community effort so I don't think this would be a lot to ask. It's practically impossible for the team to test EVERY SINGLE game out there, but with all the users at hand contributing to such a wiki page this can be tackled quite fast and effectively

These are all from memory but like I said, I'd be happy to do a bit of work in building a list of issues and post them on here if it would help.

I do recommend the official FAQ page as a startup place here: https://wiki.specnext.dev/FAQ
(I've added sections about games not working and the HDMI behavior re: multicolour/border effects games)

[Alcoholics Anonymous]

Football Manager Revisited 2018 displays a "Nonsense in Basic" error when you press a key to start, the snapshot works fine on my +2b. I can't find a working snapshot and there isn't a tap file to see if the problem is fixed by selecting a specific machine from the Next menu.

There are sometimes issues with just loading a snapshot and the game itself doesn't work typically freezing on the main screen. This could be down to a bad snapshot, but the same image typically works on my +2b.

toot_toot did you make these snapshots yourself? The problem with them is that they only work on a +2 as they require the +2 roms. They will not work on a standard 128k spectrum. Nextzxos wasn't intepretting the +2 flag in the z80 loader so it put a 128k rom in place for the game. This flag is an extension that was added to the z80 format by some emulators.

It would be much better to snapshot these games in a standard 128k mode instead. The reason is if you ask the next to save another snapshot, it's going to save as SNA which contains no information about what rom is in place and then next time the SNA is loaded it will put the 128k rom there. If you are unlucky, the same sort of thing will happen with the snapshot. If you need to save, saving via tape would be best (the nmi menu will let you mount a tap output file). I will see about how difficult it is to change the snapshot saving to z80 from sna.

The z80 loader has now been fixed and you can update your system to make it work:

https://gitlab.com/thesmog358/tbblue/-/ ... master.zip

1. Make a backup of your entire sd card contents onto a pc
2. Extract the zip's files on top of your sd card allowing everything to overwrite
3. Restore your machines/next/config.ini from your backup by copying this to the same place on your sd card. This will keep your settings including display choice.
4. Power up your next while holding U. This will begin a core update. Let that finish.
5. Pull plug on next, pull out hdmi, wait 10 seconds
6. Plug in hdmi, plug in next. The update is done.

If you don't feel comfortable doing this but you want to do the update, ask so that a time can be set up when someone can walk you through it. It's preferable to use fb messenger for this sort of thing as that's how we commonly do it.

[Alcoholics Anonymous]

There is a lot of info in this thread already but it might get lost amidst our rambles and bickerings, and also some of it is a bit too in-depth and technical for mere mortals. It'd be nice to see it collected in one place and in concise form.

Some questions then:
-is there any sort of Next wiki we could put this info in, or read about it already?
-what are the current HDMI compatibility problems/solutions?
-what are some other current compatibility problems/solutions?
-which games/soft are affected?

No takers, ok. I guess it's easier to just turtle up and go on long rambles, using some completely irrelevant tangents

2. The next must modify its video timing to generate the HDMI signal. This means programs that depend on precise timing relationships will not display correctly. Principally this means multi-colour won't display properly and some demos won't display properly. If programs take an almost entire full frame for computation and then execute a HALT to sync with the raster, this could show up as slowdown on hdmi. The reason is hdmi has fewer T per frame. If you see this I would suggest trying to speed up the machine to 7MHz to see if that solves the problem (hold nmi, tap 8 to cycle through cpu speeds; if you haven't updated yet then make sure nmi is held at least one second)

3. The +3 contention is not quite correct. There are no other known compatibility issues except for tests that check irrelevant undocumented flag behaviour. There is one outstanding program that doesn't seem to work: the recent tiratok demo which runs fine under pentagon or +3 loading but not 128 loading. It's not known why yet.

4. On HDMI you will see multi-colour games affected and games that rely on border timing. Aquaplane, Pietro Bros, Old Tower, etc.


The "extra long ramblings" are to help you understand the HDMI issue. Most people like to know the why as once things understood, it's no longer seemingly random and therefore frustrating.

The tangents are there because some in this thread are not here to discuss honestly, sorry, that doesn't apply to you. There is a history that you probably don't know about.

[ZxSpence]

Fascinating, but when you think about it 50/60Hz issue was always going to be a problem. Great explanation as well.

[PeterJ]

[mention]Alcoholics Anonymous[/mention]

Thank you for explaining the issue in a not overly technical manner. It's appreciated.

[Pegaz]

Related to this hdmi issue, is it possible to use this device on Next?
https://www.youtube.com/watch?v=nN9bXtiDmxg
It needs Pi Zero to work and the image looks very good, far better than various composite/hdmi converters.
And a very interesting text to read, with lots of details:
https://www.bytedelight.com/?page_id=1849

[TheSMoG]

Related to this hdmi issue, is it possible to use this device on Next?
https://www.youtube.com/watch?v=nN9bXtiDmxg
It needs Pi Zero to work and the image looks very good, far better than various composite/hdmi converters.
And a very interesting text to read, with lots of details:
https://www.bytedelight.com/?page_id=1849

As mentioned above it is possible to use the ZXHD on the Next with the following caveats: Only ULA modes are supported and only 3.5MHz is supported. You will need to fiddle with the autoexec.bas to enable it because if that's your only output then you'll be booting blind as the Next disables the expansion bus by default. I'm thinking the above may not be an issue for standard Spectrum games if you don't wish to accelerate them. In my opinion what many Pentagon and ZX Evo users are utilizing as well as many other retro platform users (ie the OSSC) is a much better solution as it's almost infinitely more flexible and can support ALL ZX Spectrum Next graphics modes (setup IS required and it's complicated but once you get it working it's just perfect)

[Pegaz]

You're right, I've seen also some people hooked up the ZX-Evo over a converter like this, but I honestly like this ZX-HD more.

[Seven.FFF]

I have that RGB-SCART to HDMI convertor, and it works great on the Next. It can render the full set of Next layers not just the ULA screen, and it can resync when the Next changes model timings on the fly during game loading.

Bus-watching like ZX-HD and TKPie do is an impressive feat, but it’s inherently limited to reading video RAM from what’s currently paged in and visible on the bus. I think the ZX-HD firmware could theoretically be enhanced to make it aware of Timex modes and ULAplus, but i don’t think it can access all the Next video RAM or the internal settings that govern how the layers are composited.

[uglifruit]

Could I just say a massive thanks to @Seven.FFF and @Alcoholics Anonymous for acting as the Next tech support on this forum.

I'll second this. I'm super impressed with my Next, and the HDMI thing has been explained (and looks like there will be a way to make that work, with dedicated cores). I'm using mine over RGB Scart, and am super impressed with it, both as a functional device and as a physical object.

[TheSMoG]

I think the ZX-HD firmware could theoretically be enhanced to make it aware of Timex modes and ULAplus, but i don’t think it can access all the Next video RAM or the internal settings that govern how the layers are composited.

ZX-HD does ULA+ (as stated on Ben Versteeg's site) but cannot do Timex modes AFAIK yet

[1024MAK]

For the love of (insert the name of whatever you pray to here), HDMI is sh!t. Look who was involved in it’s design. For Europe, it’s all a big fudge. See here. Please do tell me where the big mainstream European broadcasters are in this...

HDMI is promoted in order to extract money out you by flogging you new more expensive TVs. Not because it’s the best standard. And HDMI is not an open standard, it’s a closed proprietary system.

The ZX Spectrum WAS NEVER fully compliant to ANY broadcast standard. Sinclair cheated. As did many other home computer manufacturers.

Everything CPU related in a ZX Spectrum runs from the same timing system as the clock signal used by the ULA / custom logic chip. In a U.K. ZX Spectrum, this is designed to drive a PAL-I CRT TV set (625 line, 50Hz vertical / field, 15625Hz horizontal / line rate). An analogue CRT TV is VERY forgiving, hence why Sinclair were able to get a reasonable picture while taking liberties with the broadcast standard. It’s actually remarkable how many LCD TVs a real ZX Spectrum will work with.

A HDMI TV does not have to comply with a 50Hz refresh in all modes. If a TV does not provide a suitable 50Hz mode, then a ZX Spectrum producing a 50Hz HDMI output is incompatible with that TV.

About Z80 CPUs. There are at least four NMOS versions: Zilog’s original version and the official licensed versions by other manufacturers (such as Synertek, Mostek [MK3880] and SGS [Z8400]). It was reverse engineered and ‘copies’ produced by several Japanese, East European [U880] and Soviet manufacturers [T34BM1, КР1858ВМ1]. Indeed, the NEC version [µPD780] found in most Sinclair made ZX Spectrum computers is an “illegal” (as in, not officially licensed) reverse engineered version.

Later a CMOS version [Z84C00] was developed, and a version of this is still manufactured. This is what is likely to be used if your machine is repaired.

Undocumented or illegal opcodes, and effects on registers have various effects, some of which are useful. However, as they are not part of the formal definition of the instruction set, different implementations of the Z80 are not guaranteed to work the same way for every undocumented opcode.

Mark

[1024MAK]

Not to derail the thread, but as the Kickstarter campaign says

Here is our answer: The Spectrum Next - an updated and enhanced version of the ZX Spectrum totally compatible with the original, featuring the major hardware developments of the past many years packed inside a simple (and beautiful) design by the original designer, Rick Dickinson, inspired by his seminal work at Sinclair Research.

Spectrum Next is an expanded and updated version of the ZX Spectrum, fully compatible (software and hardware) with the original. You can play any games, demos, use original hardware, you name it. And it also runs new software created more recently to make use of expanded hardware, including new graphics modes and faster processor speeds.

The Next Kickstarter campaign was launched as a machine that was "totally compatible with the original" and "fully compatible" with software. As this thread is showing, the Next isn't "totally compatible" with the original, there are many games that don't work. Maybe those issue will be fixed, but it was pointed out that the base hardware had been released for 2 years before the cased Next was released, I'm surprised those issues weren't identified or fixed because they should have been part of the basic design specification.

My issue is that post launch it's now being said that was never meant to be compatible, especially over HDMI, but I backed it and I imagine many people did, fully believing they were getting a machine that supported old and new software. The Kickstarter campaign page even has this:

The Spectrum Next is much more than just a renewed trip down the memory lane: there’s a world of new software out there that requires upgraded hardware to run -- from games to music and video players, from operational systems to ultra demos -- stuff that has been made for specific expanded hardware that most ZX Spectrum lovers never tried before, and can be quite difficult to find or install.

But now we're finding out that the Next doesn't actually support a lot of new games and demos, especially over HDMI. Again, hopefully this will be fixed.

Hopefully by listing games that are not compatible or behaving as normal, we can see fixes being implemented in the Next. Saying that the Next was never meant to be compatible with the original Spectrum is wrong, as is clearly stated on the Kickstarter page and it shouldn't be given as an excuse.

Please show me a Sinclair or Amstrad made ZX Spectrum that has HDMI video outputs...

Was the ZX Spectrum 128K fully compatible with the 48K model? No. Was the Amstrad produced +2A, +2B, +3 and +3B fully compatible with any of the earlier machines? No.

If you guys don’t want your Next, just sell it to someone who does want one.

Mark

[1024MAK]

But if the Next is more compatible than those extended variants, why is it I can play the games mentioned in this thread as not working correctly on the Next perfectly fine on my Spectrum +2b with DivMMC, which is notorious for compatibility issues?

Like it’s been said in this thread, the disappointing thing is that the response seems to be very defensive/argumentative instead of admitting there’s an issue and trying to resolve it. All I wanted was a Spectrum that supported HDMI, played games from SD card and was compatible with the Spectrum’s library. All of those things were promised in the Kickstarter and it would be nice knowing that if a list of incompatible games were published - even if it was over HDMI - the response would be “we’ll fix it” instead of trying to put the blame on the people who actually funded making the Next.

The explanations are always going to be a bit technical, because the problem is a technical one.

It’s similar to trying to get a part manufactured to metric dimensions to fit in place of a part manufactured to imperial dimensions. Sometimes it’s possible, other times it’s not.

Using analogue video, the Next is very compatible with a ZX Spectrum. You can see that a lot of effort has gone into making this the case.

People also wanted HDMI so they could connect their brand new Next to their new (or new-ish) TV. However, it’s not easy producing HDMI signals, especially when there are such a huge number of TVs that are “HDMI” but which do not support a suitable 50Hz refresh rate. Hence in order for the Next to be useable with as many HDMI TVs as possible, there had to be a compromise.

The overriding problem here, is that HDMI was not really designed for devices with strict 50Hz timing. The timing that the ZX Spectrum existing software depends on. There are work arounds, but they either require different compromises or more hardware.

The developers have already said that they are still working on the problem. Do you not want after sales service?

Mark

[1024MAK]

The 128k was instigated in Spain and picked up by Sinclair. It was not a large improvement.

WHAAAT!??!?
128 k?
AY chip?
Pagined RAM?
48k "compability"?



(Joke)

Edit: https://medium.com/@uto_dev/the-awakeni ... 32c7377788

But do note that:
80K internal RAM was already available (top 32K paged),
Plug in AY music expansions were available (they were also available for the ZX81),
Serial interfaces were available (in addition to the Sinclair Interface 1 bit bashed port).

The 128K machine should have included at least one joystick port, but...
The 128K machine should have had more flexibility in what screen RAM was paged in and where, but...

Mark