SPECTRA Advanced Graphics

[cheveron]

I have always stated that I would be interested to make a 128 compatible version if there was sufficient demand.

I distinctly recall you saying otherwise. If I am mistaken I apologize. It is not the same as people repeatedly making false statements about ULAplus and it is disingenuous of you to suggest otherwise.

The design isn't incompatible; the implementation is. Obtaining the Y signal from the RGB socket is viable (tried it).

You're the hardware guy, not me, but as I understand it the device is designed for a 48K machine. Yes the technique of hanging a video device off the bus will work on the 128, but for the existing device you'd either have to modify the Spectrum, or the device, no?

I certainly wouldn't want to deter anyone from coding for SPECTRA

I'm not hostile to SPECTRA

Its extended colour scheme is worse than ULAplus in every single respect.

Personally I think SPECTRA is a dead end and I wouldn't waste time developing for it.

Oh, Ok...

I'm entitled to my opinion. I've never presented it as anything other than an opinion. I've explained why I consider the extended color support to be inferior to ULAplus and why I woudn't develop for it. I don't see why that would put anyone off. It's not like anyone ever listens to anything I say.

• RGB SCART connectivity (with all necessary signalling voltages)
  No arguments there. Not many modern televisions can take the fake PAL signal from the Speccy but with SPECTRA they will work providing they provide a SCART input. Excellent job.
  
• Sound output via SCART
  Given that SCART provides an audio carrier I would expect this. If you added a virtual AY chip with stereo output it would be even neater.
  
• Additional colours and colour resolutions (32 modes in total)
  The Timex machines have been available since 1983 and include three screen modes. These machines were quite widely available yet in the last 30 years almost no software has been written to use them. In Russia they developed 16C mode with per-pixel colour. I think the total number of titles has recently exceeded single figures. I'm sure it was fun to do from a development point of view but I will be stunned if more than a handful of titles are ever released for one of these modes, let alone all 32. Until you get emulator support in a mainstream Windows-based emulator, developing for SPECTRA is a drag. And then you've got to fight against the "if it's not attribute clashy it's not a Speccy" crowd. I'm really not knocking what you've done, I'm just suggesting you should have realistic expectations about how much software support you're going to get.
  
  
• Additional border colours and effects
  As above.
  
• Screen buffering to avoid flicker (double screen buffers)
  There are other ways of avoiding screen flickering besides double buffering. In practice the double buffer on the Timex and the 128 didn't get used very often because the overhead of copying the screen to the buffer kills the frame rate.
  
  
• ZX Interface 1 compatible RS232 socket
  Certainly useful with your programmable IF2 carts, but I can't think of many other applications.
  
  
• Kempston compatible joystick socket
  Always a welcome addition. You can disable it though right? Having two Kempston interfaces daisy chained can cause problems, especially with DivIDE+.
  
  
• Optional onboard EPROM facility[/quote]
  I take it that' replicates the functionality of your programmable IF2 carts.
  
  
• Optional ZX Interface 2 compatible ROM cartridge socket
  A nice touch.
  
• ZX Interface 1 compatible ROM paging mechanism for use with the ROM facilities
  Handy if you've got some kind of IF1 file system support, but possibly not so much use with divIDE or Spectranet.
  
  
• Reset button
  
• Full width rear expansion bus with gold plated connections
  Very nice. ThHroughports are always appreciated.
  
• Configuration switches to ensure full I/O compatible with all existing Spectrum devices

Impossible. Even if you kill all of the I/O and pass all the signals out of the back without changing them, just by adding length to the lines you will render some interfaces unusable. That's not your fault of course. Unfortunately, software authors can't know what devices a user has plugged in, so will have to go through a series of diagnostics to determine if it is safe to enable various features, or just assume it is safe and risk not running on some configurations. That's why I came up with the ZXI standard. If you want to switch to using I/O in that range then it's not too late. There are plenty of spare ports. Just have a word with Guesser or one of the people that maintain it.

So ULA+ has 4x1 Attributes mode too?

No, because that mode takes too much RAM and too much CPU to make much use of.

Too much RAM for what application? Too much CPU for what functionality? So even for a graphics editor or a word processor it wouldn't be useful? Too much for a game perhaps? Then use the 4x2, or the 4x4, or the 4x8, or 8x4, or the 8x2, or the 8x1, all either using standard colours or the enhanced colour palette. An application can pick its preferred trade off between number of colours, colour resolution and RAM usage.

I'd be shocked to see a new graphics editor or word processor released for the Spectrum. On the other hand if you're writing one then good luck.

People haven't even begun to scrape the surface of what's possible with ULAplus. For instance 24 color backdrops with no CPU overhead, palette cycling, and I'm sure there are others

I know what you mean. For instance, the double screen buffer mechanism of the SPECTRA interface allows a simple interrupt routine (consisting of little more than an OUT instruction) to toggle between the two screens every frame and when used on an LCD/LED TV (which most are these days) can produce a 512 line display in any of the new display modes with very little CPU effort.

Not a 384 line display? How does that work on a 720p or 1080p display?

And of course a CPU routine could be used to switch between the display modes midway through each TV frame to generate a hybrid mode display.

Yeah, did that on the Timex over a decade ago:

And the ROM facilities coupled with the ZX Interface 1 compatible paging mechanism provide a convenient persistent way to extend BASIC, allowing the potential for new BASIC commands to control all of the enhanced display modes (some can already be controlled using standard BASIC).

You have to be careful with that when using devices like Spectranet, or other things which also use a shadow ROM. Basically if you want to work with modern storage you're limited to a single BIOS ROM. Although of course you could write SPECTRA commands for esxDOS or Spectranet. Or just use Boriel's ZX BASIC.

SPECTRA really doesn't support existing software without a rewrite

SPECTRA supports all existing software to reproduce them in their original colours in clarity not generally seen from a 48K Spectrum. It will not recolour existing games if that is what you meant but did not actually write.

It's a forum. I don't spend hours composing my posts. I thought it was implicit.

How many Timex Software tilles are using Hires colour mode, apart from some demos?

More than there are SPECTRA titles.

Nice dodge of the question there.

Oh please. It wasn't a dodge. I just don't have the figures to hand. If you want to go check out the Timex archive at WoS and count them yourself be my guest. My point was that the availability of a video mode doesn't translate into software releases.

The problem is that even after you deliver new hardware, it's insanely difficult to get anyone to write anything to support it.

Indeed. I wonder if it helps having people go out of their way to belittle new interfaces?

Oh please. I have not gone out of my way to belittle SPECTRA. When you released it I expressed my disappointment that you had not included support for ULAplus, which you certainly could have done if you'd wanted. This is the first time since then that I recall writing anything about it, and only because I was annoyed at LCDs description of SPECTRA as being "better" than ULAplus. To my mind they are different things. ULAplus is the defacto standard for enhanced video. Even in Russia where they prefer to come up with their own solutions they are building clones which support it. SPECTRA is a neat interface. It just doesn't interest me personally.

And then there is always the Windows based emulator with SPECTRA support I have been designing... (well if you want something done, do it yourself I say)

That's a smart move on your part. I look forward to trying it out.

I am sorry that people have been waiting for it for so long, but that's not something I had any control over

Well you could do what I did and learn the necessary technologies, put a lot of time and effort in and be prepared to spend a fair amount of money on the development and production costs...

As I pointed out the last time you said that, I have already spent a lot of time (thousands of man hours) and money (hundreds of pounds) on developing for the Spectrum and it's up to me how I use my time and money. I'm not pushing ULAplus on anyone, I'm just trying to correct some common misconceptions. ULAplus is available in hardware, and it is good for more than recolouring old games.

I still think SPECTRA would have had a bigger market if you'd supported the ULAplus standard. That's my only criticism of the device. Nothing I've said was intended as a criticism of you. It's your time and money, spend it doing whatever you find the most rewarding.