Search found 1869 matches

by RobC
Tue Jan 23, 2018 9:53 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

I've put a video up showing SpectROM in action: https://youtu.be/ULzpLhT43ac

It's just me playing some games badly but it shows the current state of play. (The quality isn't great - I need to sort out how to do captures from my DVD-recorder again...)
by RobC
Tue Jan 23, 2018 7:09 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

I think you still can: you just reserve logical colour 8 for the border, and have the parasite translate all 'bright' blacks to logical colour 0 instead of 8...and assuming you're still doing a further lookup to your extended palette once you've got a logical colour number Yes - I think you're righ...
by RobC
Tue Jan 23, 2018 5:49 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

I've recently got hold of a Thomson MO6 and I think it has an attribute mode with exactly that format. I'll look at implementing the flashing stuff in software and see how it performs. (Sorry Dave!) Of course, the problem with implementing a true 4-bit/4-bit attribute mode is that it has 16 physica...
by RobC
Tue Jan 23, 2018 3:13 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Rob squeezed an extra attribute mode into the VideoNuLA. So bascially byte pairs form {attribute, 8 pixels at 8MHz/pixel}. The attribute is exactly in Spectrum format, including 1 bit each for BRIGHT and FLASH. It'd be nice if the attribute were simply 4 bits 'ink', 4 bits 'paper', but that'd make ...
by RobC
Tue Jan 23, 2018 3:10 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

So Rob, when are we going to see a video of this in action then? :) I'll try to put something up tonight. I've put in a fast whole-row transfer and have been using the border to watch how much of the frame is taken up with each type of video update. It's much better than it was but still not quick ...
by RobC
Tue Jan 23, 2018 10:10 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Or have I got completely the wrong end of this stick with the need for additional display memory? No - you're spot on. I'm using a 640x256 mode 0 so no tweaking of the 6845 anymore, just VDU 22,0. I'm then filling character rows 0-3 and 28-31 with 0x80. I'm also filling the first and last four char...
by RobC
Tue Jan 23, 2018 8:35 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Dave: I'm afraid that I've had to change the VHDL again to get the border in: The Spectrum display effectively has 17 logical colours (16+border) but only has 15 physical colours as bright and dark black are the same. Ideally, VideoNuLA would implement border control but it doesn't get the required ...
by RobC
Mon Jan 22, 2018 10:22 am
Forum: hardware
Topic: Files from modern PC to DFS disk....
Replies: 13
Views: 222

Re: Files from modern PC to DFS disk....

The only real objection I have to this is the licensing. Yes - I see your point. I've probably paid for a few copies of each now as I've upgraded laptops etc. Having said that, they work really well and ADFS Explorer's ability to read an ADFS hard disk image, instantly *compact it and then have it ...
by RobC
Mon Jan 22, 2018 9:22 am
Forum: hardware
Topic: Files from modern PC to DFS disk....
Replies: 13
Views: 222

Re: Files from modern PC to DFS disk....

sydney wrote:You can do it in beebem by creating a blank image then using one of the menus - edit I think - and use the import files option.

Possibly.

Yes, I've used this feature in the past. It's under Edit->Import files to Disc.
by RobC
Sun Jan 21, 2018 10:55 pm
Forum: hardware
Topic: Files from modern PC to DFS disk....
Replies: 13
Views: 222

Re: Files from modern PC to DFS disk....

I use DFS Explorer under Windows: https://www.g7jjf.com/dfs_explorer.htm

It's shareware and the registration cost is £5. I also use ADFS Explorer for doing the same thing with ADFS disks and hard disk images.
by RobC
Sun Jan 21, 2018 8:05 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Sorry for not testing this sooner Dave but it's my sister's birthday today and we've been doing some family stuff... I assumed the numbering of the logical colours follows the spectrum order, so that the emulator doesn't need to do any conversion. So normal blue would be colour 1 and normal red woul...
by RobC
Sat Jan 20, 2018 7:02 pm
Forum: hardware
Topic: Beeb FPGA
Replies: 476
Views: 28201

Re: Beeb FPGA

I've had a go at the Speccy mode now. Here's a sample screen I converted coming out of the VideoNuLA in BeebFpga: Great stuff =D> Rob, the only thing I wasn't sure about was the packing of the 4-bit foreground and background colour in the attribute byte. Which way around are they? At the moment, I'...
by RobC
Sat Jan 20, 2018 8:46 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

I have one of these for my Spectrum. And it is awesome - emulator quality output! I believe it works by ‘listening’ for writes to the screen RAM in order to produce its picture but am not 100% sure. http://www.fruitcake.plus.com/Sinclair/ ... erface.htm Thanks - I'd not seen that before. It's a gre...
by RobC
Fri Jan 19, 2018 9:46 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

The issue is that we want to ensure that actual screen writes on the host are done at the same raster position as emulated screen writes. My idea is to set up a free-run VIA timer set to interrupt every 4 scanlines (256us); all the interrupt does is increment a counter (which is reset on VSync). No...
by RobC
Thu Jan 18, 2018 9:47 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

I would think that your flicker is mostly caused by not syncing VSyncs on the host with your emulated HALT on the parasite. I would expect most games to use that to avoid flicker as much as possible, even those which have to present the back buffer via the SP or unrolled LDI techniques (as this can...
by RobC
Thu Jan 18, 2018 9:12 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Thanks Rich - that's really useful. I've read a little bit on Spectrum games but don't really do Z80 so it's all new to me. At the moment, I'm just running a set number of t-states per frame (~70,000) and then doing the host stuff with wait for vsync in the screen refresh. So, the Z80 core is effect...
by RobC
Thu Jan 18, 2018 8:34 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Which issue is that? The only difference is that the Master keyboard has 16* columns to the Beeb's 10 columns. (*ok, technically 13 columns) The Master always returns the lowest key found provided it's greater than the start key given in X (as described in the Master reference manual). So, I was ch...
by RobC
Thu Jan 18, 2018 7:25 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Hi Dave, Is there any possibility you could save a sample screen of a game running on the emulator? Sure - I'll just have to add a function to dump out the video memory and attributes. It'll probably not be until tomorrow though as I'm looking at speeding up the keyboard handling tonight. (Annoyingl...
by RobC
Thu Jan 18, 2018 4:15 pm
Forum: hardware
Topic: Large project box
Replies: 5
Views: 253

Re: Large project box

in the early days you had ( it think it was from sideway) a metal box , with open space for flatcable to beec what was covered with a half metal box with holes for two drisk drives. maybe they are still around in uk ? or make something like that. from metal ? I think I've got a couple of these some...
by RobC
Thu Jan 18, 2018 10:04 am
Forum: hardware
Topic: Acorn Z80 manuals
Replies: 1
Views: 135

Re: Acorn Z80 manuals

Thanks for this - it's great to have them scanned.
by RobC
Thu Jan 18, 2018 8:44 am
Forum: hardware
Topic: Newbie question regarding first machine
Replies: 16
Views: 460

Re: Newbie question regarding first machine

I'd go for a B or a Master as a first machine. The B+ and Compact tend to be much harder to find and so are more expensive. From an interface/peripheral perspective, the B, B+ and Master are very similar (apart from the speech chip and cartridge port) so you could try running the different machines ...
by RobC
Tue Jan 16, 2018 8:42 am
Forum: for sale / freebies
Topic: VideoNuLA boards
Replies: 43
Views: 3920

Re: VideoNuLA boards

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...
by RobC
Sun Jan 14, 2018 9:57 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Batman the movie Beach buggy simulator More tea vicar (lots of particles) Repton 1 and 2 ported by Gil who wrote Jeltron with me in the 80s. No scrolling, but what does bomb Jack look like ;) Thanks tricky. Haven't tried Bomb Jack yet but I played the Spectrum version on an emulator when I was look...
by RobC
Sun Jan 14, 2018 7:18 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

A good *test* would be running z80 BBC basic for the spectrum on it. Great idea - I'll try it as soon as I can. The emulator can only load snapshots at the moment but I can add ROM loading. This looks really cool! Waiting patiently for the release. Can we update VideoNula ourselves, or do we have t...
by RobC
Sun Jan 14, 2018 4:32 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

mlouka wrote:When trying out your ZX81 emulator, I ended up using a real ZX81 as a "keystrip"!

Good idea :D I've now setup my Spectrum next to the Beeb!
by RobC
Sun Jan 14, 2018 10:25 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Wow, wow and wow! From pun to reality in a very short period of time. Amazing! Thanks - the idea was all yours though :) . Progressing from the ZX81->Jupiter Ace->Spectrum helped. When will I be able to play Bards Tale? I'm going to try to get something usable out in the next week or so. I'm also h...
by RobC
Sat Jan 13, 2018 10:16 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

This looks really cool. Thanks Dave - it wouldn't be possible without the Pi co-pro :D It's a lot of fun running a Spectrum on my Beeb but I'd forgotten just how many keywords were crammed onto the keys and it's really hard when the keys only have the letters on them. However, my six-year-old daugh...
by RobC
Sat Jan 13, 2018 6:11 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

crj wrote:If you're writing to the tube from emulated hardware, i.e. directly within the PiTubeDirect code, maybe you can be certain of keeping the FIFO from becoming empty? If so, you could go a little faster by not polling the status register.

Good point - I'll give it a go...
by RobC
Sat Jan 13, 2018 5:54 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

If you are going to hack around in OSWRCH, isn't it more efficient to keep a copy of screen memory on the Parasite and send actual values rather than values to EOR, by the way? This is how I do it with my emulators (ZX81, Ace and Spectrum). I've now implemented the equivalent of hoglet's OSWRCH mec...
by RobC
Sat Jan 13, 2018 4:34 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 74
Views: 1718

Re: SpectROM - Speccy emulator for the Pi co-pro

Isn't the defined - and quickest - way to do this stuff for the Parasite to provoke the Host into initiating a memory transfer? 256-byte blocks can be transmitted at the rate of 100Kbytes per second, because of the reduced handshaking overheads. And the Beeb end can do what it wants with each byte ...

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