Post by Vyper68 on Sept 17, 2019 8:31:29 GMT
As you may have seen in our puddykat thread ( atari.boards.net/post/23803 ) I have just obtained a new modern and greatly enhanced Video ULA for my BBC Micro ( herefore A.K.A "The Beeb" ) So now I have had a chance to play around with it I thought I would share some of my thoughts on this little PCB.
So to start let's get a bit of background on what the Beeb can output as it stands ( this also applies to the BBC B+, Master & Master Compact as well ) The Beeb has several screen modes and some are text only, one is Teletext only and the others are text/graphics and come in various resolutions and available colours. So here are the two most commonly used graphics modes based on the games I have played.
Mode 0 - 640 x 256 with 2 colours from the available 16
Mode 1 - 320 x 256 with 4 colours from the available 16
Mode 2 - 160 x 256 with 16 colours from the available 16
Moving onto the colours available 16 sounds not too bad, maybe like a C64 or Amstrad but you would be wrong. The BBC was designed a lot earlier and the colours are a bit more limited. The colours 0 - 7 are normal colours and are the same as available on a ZX Spectrum ( Black,White,Red,Magenta,Blue,Cyan,Green and finally Yellow ) the remaining colours 8 to 15 are flashing ( oo-errr ) versions of the first 8 so you would get Blue/Yellow or Cyan/Magenta. So in reality you only have 8 useful colours for games. Which goes to explain why Beeb games have a very "Primary" colour palette. Hardware scrolling is available in the Beebs ULA but it is still quite "jumpy". So it's safe to say it is not in the same league as the A8's in it's standard form.
Enter the VideoNuLa..
This is a drop in replacement for the standard Acorn ULA and fits all BBC Models ( No Electron version sadly - given the ULA in the Elk contains more than just Video ) so if you have a Model B,B+ or the Master series you can fit it fairly easily. I say fairly as some models have the ULA soldered to the Motherboard and you would need to remove the old ULA, fit a socket and then fit the ULA. Most Beebs have the ULA socketed so that makes life a lot easier. Once fitted into the socket previously occupied by the old ULA you then connect a single flylead to Pin 37 on the System 6522 ( IC3 ) and fit the support EPROM into a spare sideways ROM socket. Power on and provided there are no problems you will be greeted with the normal welcome screen.
The support ROM has some utilities to redefine the 16 colours available to any one of the 4096 available instead of the default colours as mentioned above. You can then save that palette and load it back in whenever you want to. There are also some presets available to load for some of the more popular games on the BBC. So it's a case of load the palette and then load the game. The new ULA also supports much smoother hardware scrolling as well so that is an added bonus.
Along with the extra colours there are new Modes which again allow for better resolutions and more colours than the standard Beeb, in addition to the high level utilities on the ROM you are also able to write directly to the ULA or by the normal *FX or VDU commands.
As an added bonus if you have a Raspberry Pi and a Co-Processor Header PCB you can run the NuLA in a native ARM environment ( I have a +3B so in my case 1.4Ghz ). This opens up more options like a CPC emulator - So you can play CPC464 Games on your BBC Micro! ( 64K only at present - but still an amazing feat ) there is also a ZX Spectrum emulator as well.
There is a working version of Doom as well but sadly I cannot play it as you need an IDE interface and some kind of Mass storage to stream the data into the Beeb. The screenshot shown previously gives an idea on what it looks like.
So first impressions are really positive and it gives the BBC a real boost in terms of graphical ability, there are some reworked versions of classic games ( the NuLa version of Frogger is pretty much arcade perfect ) So this is one upgrade I would really recommend.