Prevue Guide Forums

I remembered something about the later versions of Prevue Channel and TVGC for Amiga that may be interesting to find out.

At the 1:48 mark in the video from YT below
http://www.youtube.com/watch?v=D-pBiMD9aCY

Something interesting happens to the grid. The grid shrinks down to two listings, instead of the usual 3. I remember, way back when, that this started after the 1998 revamp of the channel. This continued through its days on TV Guide as well.

One of the commands that are missing from the Wiki may be the code that tells the software to shrink down to two listings and another code to return it to the 3 listings.

What do you think?

Steven

nwgatwcfan wrote:One of the commands that are missing from the Wiki may be the code that tells the software to shrink down to two listings and another code to return it to the 3 listings.

Yep - I'm pretty sure I noted somewhere before on this forum that the "PrevueSport" variable that shows up when you hit one of the diagnostic keys probably refers to this capability. Also, note that we are missing a LOT of commands from the wiki, not just a couple, since we don't know a lot of the Amiga-specific ones

One thing I think we are missing that probably IS already on the list in the wiki is a command for both Amiga and Atari to edit the attributes of an ad - enabled, and amount of lines. tin, any thoughts?

Hard to say at the moment. Maybe in command L. I have finally got back into the Atari disassembly (although it will be slow, I don't have the time to devote that I had earlier this year) so I may learn some more soon. Command N is the only other Atari command that I currently have no idea what it does.

Regard the scroll down, I am sure that will be one of the 110 baud commands we're currently investigating as it's related to the content broadcast on the top half. I really want to post about the 110 baud reverse engineering but I'm not sure where to start. I think I'll tidy up the scripts and put them on here for people to try. I also found I think PG is not compatible with PAL Amigas so I am screwed for trying it on real hardware (and have pointlessly purchased several A2000s!!!)

I also note in the video you can see the satellite delivered guide just behind the local version (on the left) and it doesn't scroll back down, instead immediately moving to the lower position. This makes me wonder if there was a slightly different central prevue guide software.....

Tin,

You know, I never noticed it before, but you're right. The background satellite listings do drop extremely fast compared to the cable listings. Considering at that time the A3000/A4000 computers were being used in some instances, I'm wondering if they used the satellite listings as a test of the newer systems?

Steven

tin wrote:Hard to say at the moment. Maybe in command L. I have finally got back into the Atari disassembly (although it will be slow, I don't have the time to devote that I had earlier this year) so I may learn some more soon. Command N is the only other Atari command that I currently have no idea what it does.

Regard the scroll down, I am sure that will be one of the 110 baud commands we're currently investigating as it's related to the content broadcast on the top half. I really want to post about the 110 baud reverse engineering but I'm not sure where to start. I think I'll tidy up the scripts and put them on here for people to try. I also found I think PG is not compatible with PAL Amigas so I am screwed for trying it on real hardware (and have pointlessly purchased several A2000s!!!)

I also note in the video you can see the satellite delivered guide just behind the local version (on the left) and it doesn't scroll back down, instead immediately moving to the lower position. This makes me wonder if there was a slightly different central prevue guide software.....

Ah, okay. Do you know what the O and E commands do though? Also, you must be right about the PrevueSport command, it's probably with the 110-baud commands. I was planning on posting about that stuff if/when I get more information from the person who implemented it, but we'll see when that happens.

I had noticed that the guide in the background shrinks instantly instead of gradually - maybe their timing system was somewhat approximate, and they wanted to make sure that the background guide was definitely gone by the time the foreground guide had shrunk. Maybe even an older version of the foreground guide shrunk instantly like the background one, and they kept the background one as jumping instantly to support machines that were running older software, or maybe they just hadn't updated the background one. I don't know, but I feel like there's a million reasons they could have done this, and we probably won't ever find out I think they probably are running some sort of different software on the C-band guide though...

nwgatwcfan wrote:ou know, I never noticed it before, but you're right. The background satellite listings do drop extremely fast compared to the cable listings. Considering at that time the A3000/A4000 computers were being used in some instances, I'm wondering if they used the satellite listings as a test of the newer systems?

Not convinced that's the reason... If A3000/A4000 computers were being used, they shouldn't necessarily run a different version of the software (they could certainly build a version that could run on A2000/A3000/A4000 if they wanted to). Plus, it doesn't make too much sense that they would use a test version in the central office, since if the test version crashed, it would send gurus to every Amiga through the satellite (unless, of course, they genlocked it differently, which is certainly possible). Still, I think you get what I mean when I say that they would probably want a more stable version running if it's the heart of every Prevue Channel installation.

To be honest (and yeah we are all speculating and my speculation has been wrong in the past) I think the scroll was done by the PG machine for the nice look - and it probably was always like that, because the ability to scroll the position of the guide had been in PG since at least the prevue list versions. Look at some of the youtube vids when the menus are used or it boots up, it scrolls right down from the top. Plus I figure it's using one of the lovely features of Amiga hardware, the screens (AFAIK the earliest implementation of virtual desktops) where the guide portion is actually a full screen, scrolled halfway down the viewable area. This also figures in that the upper part can be an different screen resolution to the lower half, and that when one presses shift-D for example, there are still approximately another 1/2 screen's worth of listings that were off the viewable area that come onto screen before it stops and restarts the listings.

I guess the use of an immediate move at the central for c-band listings was just so, as AriX speculates, it would be out of the way before the local PG box began their scroll. I presume the low speed of the 110-baud stuff also made 100% accurate timing a problem.

@nwgatwcfan - like AriX says, the difference at central won't be due to speed of the computer, rather it's done on purpose in the code.

In terms of genlocking, I guess it's probably actually done the same way at Prevue central, except of course the version of code there did not ever generate overlays on the top half, and had tweaks such as this to get the listings out of the way immediately when the control code came through. I guess this only because it seems to me to be the most obvious way to keep everything in sync, but maybe a more professional composition was done at the centre.