ZX-UNO 65 --- a ZX Uno port for the MEGA65

Zitat von adtbm

PSS: out of interest, did you try the ZXuno on the MEGA65 already ? How do you come along ? Do you have Soectrum experience ?

Yes, and yes! Although my first computer experiences were on a Commodore PET, I grew up with mainly Sinclair and Acorn machines, and I'm a great Spectrum fan.

I haven't had a lot of time to spend with the new ZX-Uno core because I'm pretty busy with work at present, so my free time is limited. Nevertheless, I've installed the ZX-Uno core and tested it to some extent, and first impressions are very positive.

In particular, I'm impressed with the amount of thought that's been put into the Spectrum-to-MEGA65 keyboard mapping. That's been really well thought through and works very nicely. Yes, it does mean that you need to read the documentation first, so it's not 'quite' plug-and-play… but that's always going to be true in terms of finding out how a non-Sinclair keyboard works when used with a Spectrum. The couple of minutes it takes to read about this is time well spent.

I haven't had time to try out much software yet, but what I've tested works fine.

The first and most useful thing I did was to replace the standard esxDOS NMI menu with Bob Fossil's Browse for esxDOS and ZX-Uno, which provides a much superior file browser with long filename support. This vastly improves the usability of the SD card browser software, and should almost certainly be preinstalled (or, at least, recommended as part of the setup procedure).

I'll spend more time actually testing the core later, but so far it seems to be working well.

I think the worst current limitation is the VGA-only restriction. I do understand that in order to get accurate timings it's necessary to output at 50Hz and adapting the display for HDMI is fraught with problems. I'm lucky in that my monitor has two inputs and supports 50Hz, so I've got both inputs attached to my MEGA65, and if I use the Spectrum core I can just switch inputs and see the picture. So it's only a minor inconvenience for me at present, but for some users it could easily be a show-stopper. Maybe the issue could be resolved (without loss of timing accuracy) through use of a frame buffer? However it's done, getting the Spectrum core to output video (and, ideally, sound) through HDMI as well as VGA would be highly desirable.

But anyway, great work so far on this! It's very usable. As I've said before, I would have really liked it if this could have been a Spectrum Next core for the many extra features it provides, and for the overall easier 'automatic compatibility' – e.g. all that messing about with OUT commands to make certain old games work on the ZX-Uno (as discussed in the tutorial) isn't necessary on the Next. (And ironically, there IS already a Next core for use with an actual physical ZX-Uno…!) But I do understand why a Next port hasn't happened, and the ZX-Uno is certainly the next best option for widespread Spectrum compatibility. Bottom line is that this is a great core to have on the MEGA65, and I'm glad it's been done.

Zitat von adtbm

Hi Richard Hallas ,

these are great news, (i've already suspected that you're a huge Spectrum fan )

I am! Though I loved other systems too (notably the BBC). I like to think I was open-minded – I never had much patience with 'platform wars'. The different machines were all too interesting for that. I was particularly fond of the Spectrum, though, because it was such a fantastic compromise: it really exceeded the sum of its parts and could compete very well with anything else on the market (and for a long time, too).

Anyway, just a few points in response:

1. Concerning Browse by Bob Fossil… I was actually reminded of this by Andrew Owen, so I shouldn't really take credit for the lead. (It also means that your team should already be aware of it, I think…?) I'd actually looked at it previously, at a much earlier stage in its development, but I'd forgotten about it and Andrew reminded me. It's come a long way since I first looked at it and is now really useful.

It's not quite as nice as the Spectrum Next's browser, but it's the closest thing you can get for esxDOS and it's tremendously helpful.

2. Solution for digital video out – brilliant! I look forward to learning more about this. I'd say it's certainly the most important thing to address with this core at present.

3. If you'd like me to help with beta-testing or anything specific, feel free to contact me directly. I'd be happy to help if I can. (Email address is "Richard (at) Hallas.net".)

4. I'm glad you have plans to tackle the OUT command issue, too. That really is a pain. It affects machines other than just the ZX-Uno (e.g. I know it also affects the Omni Laptop, and maybe other Harlequin-based designs). But it didn't affect the original Spectrum, and it doesn't affect the Spectrum Next. It makes the Spectrum really unfriendly: users shouldn't be expected to have to remember those obscure numbers, or when they need to type the commands and when they don't. They should just be able to type LOAD "" (or occasionally LOAD ""CODE), as on an original Spectrum, and expect the game to load and work properly. So, if you've got some sort of solution in progress, that'd be really great.

Zitat von adtbm

To be honest, i laughed out loudly and told Andrew, it's amazing, how small the world is.

Very true!

Zitat von adtbm

what i imagine is a small NMI configuration menu, where you could easily select Speed, RAM size, configure/bind joysticks, etc.

That's an excellent idea. It could also include a handy way to enter POKEs directly, or even load a .pok file into memory, to cheat or apply a patch.

One other small idea that this menu could include…

On the Spectrum Next, when in native NextZXOS mode, if you bring up the NMI menu it contains a Keymap menu item, and choosing that displays the keyboard mappings for whatever ROM is currently loaded. For example, when the ZX80 and 81 emulators are loaded, it shows the keyboard layouts for those machines. (In fact, they have a choice of key mappings, and you can toggle between them here.) In Next mode it shows the NextBASIC command line keyboard layouts, including the special editing command keypresses that used to be only available on the Spectrum 128's separate keypad (which was only ever released in Spain, not in the UK!) – they've been remapped on the Next to be available through the main keyboard. It also toggles between that screen and another, showing an editor command summary in tabular form. And in 48K Spectrum mode, it shows a complete diagram with all the original keywords etc. on the keys.

I was responsible for creating these various screens on the Next. (They're standard Spectrum screens that are just loaded into screen memory on demand, for a quick reference.) It occurs to me that it might be possible, and indeed useful, to devise some sort of similar screen for the MEGA65's ZX-Uno core that shows a summary of the Spectrum-to-MEGA65 keyboard mapping in either graphical or tabular form. Then, when users are new to using the MEGA65 keyboard to access the Spectrum functions, they could just press the NMI button, call up the keyboard help screen, and see a quick, useful summary of how to access what they want.

I haven't thought this through yet (the idea's only just occurred to me), but if it sounds as though it might be a useful idea and you'd like me to come up with something, I'm pretty sure I'd be able to devise a suitable help screen.

Zitat von adtbm

So please, if you do further testing, report everything you notice. ideas, bugs, whatever.

All this is helpfull to make this ZX-UNO 65 core user friendly !

Will do!