VideoNuLA boards

[1024MAK]

Given the price for a 28pin one of these, I think you're best off just getting some more NuLAs.... http://www.ebay.co.uk/itm/172803690952

d.

I prefer Farnell's price

Mark

[MartinB]

If I'm reading Toby's page correctly, you can get 28-pin headers a lot cheaper - £0.60 for one + VAT + £3.95 postage as far as I can see?

https://www.toby.co.uk/content/catalogu ... =606-xx-R1

[danielj]

Phew!

Clearly searching for the wrong thing

d.

[RobC]

I prefer Farnell's price

I've found out where I bought mine from: Unicorn Electronics

[RobC]

I've made another batch of boards in preparation for the RISC OS London Show.

If you're coming to the show, you'll be able to see VideoNuLA in action and have a play with it. If you want to purchase one (or more!), I'll have units available to buy on the day. I'm also giving a talk on its development for those who want to find out more.

For those who want one but aren't coming to the show, just PM me or express your interest in this thread.

Price is £50 per unit (plus £2.50 P&P for UK delivery). I can get postage quotes for those living overseas.

[mattyj]

Hi Rob
Could I purchase one of these boards please?
Kind regards
Matt

[jgharston]

Writing to &FE23 toggles between writing index*16+red and writing green*16+blue. Is there some way of resetting the toggle to a known state so that you know that your next write to &FE23 is going to be, eg, the index*16+red ?

Edit: the manual says writing &4x to the control register reset nULA to its default state, then lists these default states, but the &FE23 toggle is not listed in that list.

(I'm getting weird deja vu, I'm sure I've asked this before....)

ta.

[RobC]

Edit: the manual says writing &4x to the control register reset nULA to its default state, then lists these default states, but the &FE23 toggle is not listed in that list.

The reset command (?&FE22=&4x or *VNRESET) also resets the toggle state so that the next poke to &FE23 sets the index and red component. I'll add this to the manual.

Also, following Lardo Boffin's "SpectROM" suggestion, I've recently revised the VHDL to make a little extra room in the CPLD and have added another attribute mode which can replicate the Spectrum's display (it's actually closer to the Thomson TO7 as attributes affect an 8x1 pixel block).

I'm currently working on a Spectrum emulator for the Pi copro to go alongside it. It's in its early stages so I'm not sure how useful it'll be but, if it does turn out to be of use, I'll upgrade existing boards for free.

Also, if anyone wants a board, I still have a few bare PCBs that I can make up over the holidays. There are still some listed on eBay but they are more expensive to cover the eBay fees...

[jgharston]

Edit: the manual says writing &4x to the control register reset nULA to its default state, then lists these default states, but the &FE23 toggle is not listed in that list.

The reset command (?&FE22=&4x or *VNRESET) also resets the toggle state so that the next poke to &FE23 sets the index and red component. I'll add this to the manual.

Thanks. A suggestion: put a "parameter" column in the auxilary register summary table on on page 28 as an aide memoir, something like:
code | function | parameter
1 | set palette mode | physical/logical mapping
2 | set horizontal | offset offset
3 | set left blanking size | size
4 | reset | none
etc.

It turns out the reason I tearing my hair out was that I was programming the physical pallette using logical mapping. (I've programmed colours 0-3, why is the blue still blue???? Oh, that's physical colour 4....)

Also, if anyone wants a board, I still have a few bare PCBs that I can make up over the holidays. There are still some listed on eBay but they are more expensive to cover the eBay fees...

Yes please! I've currently been testing code with the beta B-Em - which fights with AVG over control of my machine.

[RobC]

Thanks. A suggestion: put a "parameter" column in the auxilary register summary table on on page 28 as an aide memoir, something like:
code | function | parameter
1 | set palette mode | physical/logical mapping
2 | set horizontal | offset offset
3 | set left blanking size | size
4 | reset | none
etc.

Will do. I should have some time to revise the manual and support pack over Christmas alongside the Spectrum emulator work...

Also, if anyone wants a board, I still have a few bare PCBs that I can make up over the holidays. There are still some listed on eBay but they are more expensive to cover the eBay fees...

Yes please! I've currently been testing code with the beta B-Em - which fights with AVG over control of my machine.

Great - I'll PM you the payment/PayPal details (cost is £52.50 including UK P&P).

[jgharston]

I missed getting a nULA at ABUG, so have been experimenting with the implementation in the current beta of B-Em.

I decided to update my screen saving/loading tools to add support for 12-bit palettes. I started with my *ScrSave/*ScrLoad commands, but they store the palette in the load/exec addresses, and you need 192 bits to store the 12-bit pallet, so would have to look at including the palette data in the data stream itself.

So, I went back to the Acorn User LDPIC/SVPIC which do store the palette in the data stream, and have added support for the 12-bit nULA palette in a manner where old *LDPIC will still load new files with a 12-bit palette, and new *LDPIC will still load old files without a 12-bit palette. The palette is simply added at the end of the compressed data as 48 x 4-bit entries.

NULATEST.SSD is a couple of screen files with 12-bit palette and one with no 12-bit palette. The actual colours are a bit bleah as I just twiddled to get something as a demo.

I've been attached to ScrLoad/ScrSave as I wrote them, but LDPIC/SVPIC crunch about 10% better, and it's been easier to add the 12-bit palette, so I'm tempted to rebuild my pictures disks using LDPIC/SVPIC.

[jgharston]

The post on Spectrum attirbute mode reminds me of a discussion I was having with RobC earlier.

The VideoNuLA support ROM allows to select the extended display features with MODE/VDU 22. It currently uses MODEs &60-&68 as a straight sequence of numbers. I mentioned that it would match the native MODE numbering sequence to have the mode numbers logically numbers based the mode number they were based on, giving the sequence:

Code: Select all

MODE text clrs mem  MODE text clrs mem           MODE text clrs mem
 0  80x32   2  20K  &60 80x32   5  20K MODE 0+4  &68  80x32  9  20K MODE 0+8
 1  40x32   4  20K  &61 40x32  13  20K MODE 1+4
 2  20x32  16  20K
 3  80x25   2  16K  &62 80x25   5  16K MODE 3+4  &6B  80x25  9  16K MODE 3+8
 4  40x32   2  10K  &63 40x32   5  10K MODE 4+4  &6C  40x32  9  10K MODE 4+8
 5  20x32   4  10K
 6  40x25   2   8K  &64 40x25   5   8K MODE 6+4  &6E  40x25  9   8K MODE 6+8
 7  40x25   8   1K

That is, MODE &60+n is MODE n with 4 extra colours, MODE &68+n is MODE n with 8 extra colours, in the same way that MODE 8+n is MODE n with twice the colours.

MODE &60 and MODE &61 are the same as the straight &60-&68 numbering.

So, the question is, has anybody used the VideoNuLA Support ROM to produce code that they have released using MODE or VDU 22 with mode numbers other than &60 and &61? Of the demos I've seen they all seem to be done with direct hardware manipulation, without using the VideoNuLA support ROM, and the code I've seen using the Support ROM have only used MODE &60, I think the multi-colour text terminal (can't remember the name at the mo). I think the shuffling would also allow the Spectrum screen mode to have a number that slots in logically as well.

[jgharston]

Has anybody used the nULA board in a Master Compact? I have a floppy drive mounted internally in my Compact, before I look for my soldering iron, is the board likely to fit?

[RobC]

Has anybody used the nULA board in a Master Compact?

I have one in my Compact and it fits without any problems as long as you don't have an Econet module fitted. However, mine doesn't have a floppy inside the case so I don't know if it'll fit in yours.

I keep meaning to try putting VideoNuLA at the end of a 28-way ribbon cable - I've made up the cable but I keep getting distracted by other projects!