Palettemate / enhanced video ULA with 4096 colours

[Elminster]

As you can set the palette and then run any existing game, everything is supported.

The latest version of b-em supports it if you want to "try before you buy"

Yes indeed I had one of the first Nula’s.

But what I was looking for was a list of stuff people had actually enhanced, I was thinking of ideas for schools (to be posted in another post when I get around to it). And a videonula game machine sprung to mind. But due to limited time (same as most) I don’t want to either reinvent any wheels or put in lots of pallete changing effort.

So hence the question about a list, so I guess you and Rob have just started the list.

[Elminster]

Just to add to tricky's summary, I've modded Killer Gorilla, Hunchback and Dare Devil Denis to use 16 colours. Stewart (sbadger) modded Galaforce.

I've tried to put the demos and modded games in the support pack but it needs updating as it's missing Frogger and a couple of other demos.

So the list is in effect the demo pack at the moment + frogger. That could be enough for what I sort of hand in mind.

We need the videonula prince or persea

[RobC]

We need the videonula prince or persea

That would be awesome!

I have another demo/project on the go but it's in the very early stages. Feel free to PM me if you want more details

[RobC]

I've tried to put the demos and modded games in the support pack but it needs updating as it's missing Frogger and a couple of other demos.

I've finally got round to updating the support pack. I've included the MMC compatible versions of the Bitshifters gallery demos, the updated Spectrum emulator and tricky's NULA enhanced Frogger. The link is still: https://tinyurl.com/y75cmrxe

(Don't be put off by the February 2018 in the name - I kept it like that to ensure Dropbox preserved the link.)

[sbadger]

I've tried to put the demos and modded games in the support pack but it needs updating as it's missing Frogger and a couple of other demos.

I've finally got round to updating the support pack. I've included the MMC compatible versions of the Bitshifters gallery demos, the updated Spectrum emulator and tricky's NULA enhanced Frogger. The link is still: https://tinyurl.com/y75cmrxe

(Don't be put off by the February 2018 in the name - I kept it like that to ensure Dropbox preserved the link.)

Hi Rob, that's the old version of galaforce in the pack, there is a newer one with nula loading screen in the thread.
viewtopic.php?f=1&t=13762&p=186547
stew

[RobC]

that's the old version of galaforce in the pack, there is a newer one with nula loading screen in the thread.

Ah - sorry I missed that (and it's a great loading screen too!). I've now updated the pack to include the latest version.

It's available under the same link.

Thanks,

Rob

[Elminster]

Random thought.

If all the 'enhanced' features of videonula were hacked out, could you lose any of the hardware/reduce costs and would it be 100% backwards compatiable. What I am sort of saying is how hard/cost would it be to produce a VULA replacement as opposed to the endhance version.

Might have benn asked before, in which case I just asked again!

I was think about the idea behind Roland's Atom, and trying to keep parts as original as you can, for the Beeb equiv the best bet for realness would be to have a ROM slot that you could drop in a original ULA, and enhanced ULA or the middle ground a non enhanced ULA (CPLD).

Not sure if my rambling make sense, made sense in my head.

[RobC]

If all the 'enhanced' features of videonula were hacked out, could you lose any of the hardware/reduce costs and would it be 100% backwards compatiable.

I think it would probably only reduce the component count slightly as you would only really lose the 12 resistors from the DACs. It may be possible to use a slightly cheaper CPLD - I chose the EPM570 as I wanted space for the extra palette so didn't consider smaller designs. If the original ULA fits into something like the EPM240, it would knock a few pounds off the price.

However, about half the cost is in the time taken to build, test, clean and re-test the boards. This still takes a fair bit of time per board even though I've gradually got quicker at the soldering part!

On compatibility, it's possible to put the VideoNuLA in a fully-compatible mode by issuing *VNDISABLE ROM command (or by a simple poke if you don't have the ROM installed). This effectively tells the hardware to ignore writes to the additional registers so it behaves like the original ULA.

What I am sort of saying is how hard/cost would it be to produce a VULA replacement as opposed to the endhance version.

It wouldn't be that hard but I'm not sure there'd be enough of a price differential to make it worthwhile. If it's something that enough people are interested in, I'd be happy to look into it in more detail.

Not sure if my rambling make sense, made sense in my head.

Makes perfect sense

[dominicbeesley]

As rob says there's a lot goes into making these things. The tone testing, making the manual, developing the code and the tinge consuming process of assembly.

One thing I'd be interested if you've considered, Rob, is the pcb assembly facilities offered by the likes of pcbway. You send them the design and a parts list and they put it together. You can either send them the components or they can source them. I've never built anything production ready but I'm strongly considering it for my next batch of board as they may well involve BGA parts which i don't want to tackle by hand. I've never tried setting up a proper BOM or placement files I'd like to learn more though....

[Elminster]

Doesnt sound like it is worth doing a cut down version then.

If you wanted 100% compatability at power on, then is the only way to fudge the MOS to poke VideoNula as soon as it can?, i.e. no user intervention.

[Elminster]

As rob says there's a lot goes into making these things. The tone testing, making the manual, developing the code and the tinge consuming process of assembly.

I am sure the code is already there, and the manual would be just the fitting bit. It was more whether any saving in the BOM could offset the extra effort, and hassle of mantaining 2 different products. Aware of the issues as I am developing a board for something else (although not nearly as complicated as Videonula as it has no CPLD, just logic).

[RobC]

One thing I'd be interested if you've considered, Rob, is the pcb assembly facilities offered by the likes of pcbway.

I did look into it a bit at the outset but decided it wasn't worth it as I wasn't sure how many boards would sell and, partly down to the kind encouragement I got from you and others, I wanted to challenge myself to learn how to solder SMD parts!

I've tended to make them up in small batches to minimise my risk/outlay but, in hindsight, it might have been worth it if I'd got a large batch made up at the start.

If you wanted 100% compatability at power on, then is the only way to fudge the MOS to poke VideoNula as soon as it can?, i.e. no user intervention.

The simplest thing to do would be to just connect the A1 input/fly-lead to GND. I could produce a nobbled build for the CPLD but it would mean having to reprogram the board if you wanted to go back to full functionality.

To be honest, I've not found any original software that writes to &FE22 or &FE23 when intending to write to the original ULA and so there shouldn't be any compatibility problems. The soft disable mechanism was only added as a "nice to have" just in case something turns up.

[Elminster]

Useful info thanks.

Of course the otherway to get ULAs is to get everyone to upgrade to videonula and then buy there old working ULAs off them

[RobC]

Of course the otherway to get ULAs is to get everyone to upgrade to videonula and then buy there old working ULAs off them

Yes - unsurprisingly, I have a few spares

[KenLowe]

Hi Rob. I noticed a while ago that the mode 3 & 6 cursor on my main beeb was thinner than I remembered. I never really gave this much thought until today when I fired up another beeb and was presented with the fatter cursor in modes 3 & 6. My main beeb has a VideoNula installed, whereas the other beeb hasn't, and I suspect this may be the reason for the difference. Had a very quick look through this tread, and the user manual, but couldn't find anything relating to this observation. Is this a side effect of using VideoNula, or do I have another problem with my main beeb? It's no problem if it is a side effect. It was really just an observation.

[RobC]

Hi Ken,

It's not something I've noticed but I'll take a look at it. It could be a slight defect in my cursor emulation but I'll have to check it out to be sure.

Cheers,

Rob

[RobC]

Is this a side effect of using VideoNula, or do I have another problem with my main beeb? It's no problem if it is a side effect. It was really just an observation.

Hi Ken,

Just took a quick look at this and it looks like it's a problem with my cursor emulation in VideoNuLA. At a guess I'd say that I'm not producing the cursor when the display enable signal (DISEN) is false. If you do VDU 19,0,4,0,0,0 in mode 6 on a standard Beeb or emulator, you'll see that most of the cursor sits in the black lines below the character row. It looks like I'm not producing the cursor in that area and I suspect this is because DISEN is off and that's overriding my cursor generation. I'll check this by going through my VHDL later.

I'm really sorry about this and am really disappointed that I didn't spot this. I'll try to put together a fix today but I'm a bit worried that the CPLD is completely full after I crammed the Spectrum stuff in. If I can get a fix working, it'll then be a matter of updating the firmware.

[RobC]

So, my suspicions were correct and DISEN was overriding the cursor output.

I've now got a version of the firmware that fixes the problem. I'll obviously use this on any new boards but previous boards will need to have their CPLD updated.

If you're able to program Altera CPLDs (MAX II) then drop me a line and I'll send the new .pof file (and instructions if needed). If not, feel free to return your boards to me and I'll do the upgrade and cover return postage. I only need the VideoNuLA board (not the ROM etc.) but please do remember to enclose your address so I know who sent it to me!

Sorry again for any inconvenience.

[KenLowe]

Many thanks for looking at this, and for such a quick turn-around. Much appreciated, for what was just a minor niggle.

I should be able to do the update myself. I just need to dig out the programming hardware, and the instructions you gave me last time round. I'll drop you a PM with my email address again, so you can send through the updated .pof file. I'll then try the update this evening.

[VectorEyes]

So, my suspicions were correct and DISEN was overriding the cursor output.

I've now got a version of the firmware that fixes the problem. I'll obviously use this on any new boards but previous boards will need to have their CPLD updated.

If you're able to program Altera CPLDs (MAX II) then drop me a line and I'll send the new .pof file (and instructions if needed). If not, feel free to return your boards to me and I'll do the upgrade and cover return postage. I only need the VideoNuLA board (not the ROM etc.) but please do remember to enclose your address so I know who sent it to me!

Sorry again for any inconvenience.

Out of curiousity, are you able to reprogram boards while they're still inside a BBC Master with the power turned off, or do they need to be removed from the machine? I'm tempted to wait until an ABUG meeting where we're both in the same room and request a cheeky re-flash then, but if it needs to be removed from the machine anyway then I'll send it off now. Or perhaps just wait until I actually need a proper fat cursor in the screen modes I never use anyway.

[KenLowe]

Or perhaps just wait until I actually need a proper fat cursor in the screen modes I never use anyway.

Indeed. The only reason I picked it up is because the Level 9 graphic adventure games (which I'm using to test my new IntegraB boards) have split screen, and the bottom text section uses those screen modes!

[RobC]

Out of curiousity, are you able to reprogram boards while they're still inside a BBC Master with the power turned off, or do they need to be removed from the machine?

I usually program them inside a machine as that's the most convenient way to power them when doing the programming.

As another member has pointed out to me, I usually have my programmer and laptop with me at RISC OS shows and ABUGs that I attend in case anyone has missed out on the Spectrum update. So, if you see me at any of the events, I can do the upgrade while you wait - it only takes a few minutes.

[marcusjambler]

I usually have my programmer and laptop with me at RISC OS shows and ABUGs

I'll bring my 2 boards to wakefield for their yearly update

Marcus

[KenLowe]

I've now got a version of the firmware that fixes the problem. I'll obviously use this on any new boards but previous boards will need to have their CPLD updated.

That fixed it. Thank you again for your very prompt response.

[andrewvideo]

Hi Can some point to the enhanced video ULA . I am looking to buy one for my BBC thank you.

[simonm]

These CLPD thingies seem like moonshine magic to a software guy like me! Amazing what you guys can do with them.

[maniacminer]

Are you still making the VideoNuLA boards? I bought one a long time ago and returned it due to the snow I was getting in MODE7, I have solved that problem, so would like to buy another and try again I think I bought mine via eBay I know returned it in January 2018 (I had the horizontal snow storm coming off the characters) I never heard back whether the board was faulty or it was just my computer having a worse that the usual-terrible-bodge clock.

[RobC]

Hi,

I am still making them but usually to order and as time allows. Lack of time has meant that I'm not making as many as I used to so I've not sold any on eBay for a while but I'm always happy to make them up for folks on here. Unfortunately, I don't have any in stock at the moment but I am planning on making some on the weekend ahead of the RISC OS SW Show.

Sorry for not getting back to you - I thought we'd agreed that I'd come back if I could diagnose the problem. I didn't see the behaviour you described from your board in any of my machines so it was hard for me to give a definitive answer. However, I suspect you are right and the 6MHz clock was the cause of the problem.

I did add a 6MHz clock output to one of the jumper pads on the board as it was easy to derive from VideoNuLA's on-board 48MHz oscillator (which replaces the Beeb's 16MHz clock). The pad is physically close to a point where it can be injected into the teletext chip on the model B but you do need to cut a pin on one IC.

This should give a more stable 6MHz clock but I've not hooked it up on my machines as I haven't really seen the problem. This has been in the last couple of VideoNuLA builds but I haven't advertised it as I couldn't really see a significant improvement.

EDIT: I've just caught up with the thread about the mod you've done to generate your own 6MHz clock - it's very interesting. It might be worth us having a chat via PM.