Announcement

Collapse

Forum Rules and Etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.


Rule 1: Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.


Rule 2: Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.



Rule 3: Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.


Rule 4: "PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.


Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Rule 5: Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.


Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.


New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.


Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Multisync monitor option in early VGA cards

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Multisync monitor option in early VGA cards

    I have this early 8-bit VGA card called Paradise Pvga. It contains dip switch settings for:

    - Switch 1 Monitor Type. ON: Multi frequency, OFF: Standard VGA
    - Switch 2 VGA Mode Switching Style. ON: PS/2 Style - All modes available on all monitors, OFF: PC/AT Style - color on color, mono on mono
    - Switch 3 Not used - Set to OFF
    - Switch 4 (Not VGA Plus) 8bit vs 16bit AutoSense. ON: Auto sense 8/16bit BIOS access, OFF: Force 8bit BIOS access


    I know that in early days when VGA just came, they manufactured several multisync monitors in order to be fully compatible with all the available options from digital rgbi to analog vga to handle varying setup changes.

    I have 14" multisync CRT hence I'm tempted to use the Multisync option in the card but since there's no documents available about what it actually does, I am all the time wondering: What is the actual signal (vertical & horizontal sync amount) it outputs? Also are there any benefits to use multisync option instead of standard 31Khz VGA? I mean, if multisync monitors like mine can handle standard VGA, then why to include such option in first place?

    I have also seen multisync monitor option in Tseng ET3000AX combo cards and many other early cards and I wonder does their multisync signal differ from each other?


    Also, in paradise card the second switch says " ON: PS/2 Style - All modes available on all monitors, OFF: PC/AT Style - color on color, mono on mono". What does this actually mean???

    #2
    The multisync modes can get you higher than VGA resolutions like 800x600 and even 1024x768 (if the monitor allows) plus some crazy 132 column text modes. Don't bother with the latter; those text modes are hard to read.

    Some Paradise cards came with a program to fake other display types more accurately.

    IIRC, PS/2 systems could run color VGA displays in monochrome grey styles which the AT VGA adapter didn't do. I am not sure if Paradise was using terminology to reflect this.

    Comment


      #3
      Your card is most likely Paradise VGA Plus, with PVGA1A chipset and 256 KB of RAM.
      It supports one super VGA mode: 58h, ie. 800x600x16, and for this needs a multisync monitor.
      I suspect that with SW1 set to standard VGA that mode is unavailable.

      Comment


        #4
        Originally posted by Xacalite View Post
        Your card is most likely Paradise VGA Plus, with PVGA1A chipset and 256 KB of RAM.
        It supports one super VGA mode: 58h, ie. 800x600x16, and for this needs a multisync monitor.
        I suspect that with SW1 set to standard VGA that mode is unavailable.
        I concur. In this context "multi frequency" refers to a monitor that can do VGA plus SuperVGA. At that time there were a lot of fixed-frequency VGA monitors that could only handle 640x480, and attempting to run those at another frequency risked causing damage to them. So this switch would have blocked the card from generating frequencies your monitor couldn't handle (i.e. you had to specifically identify your monitor as "800x600 capable" using this switch).

        Eventually higher resolutions like 800x600 and 1024x768 became so common and expected that all VGA monitors were expected to be multi-frequency, but it's easy to forget that this wasn't always the case.

        Comment


          #5
          Originally posted by Xacalite View Post
          Your card is most likely Paradise VGA Plus, with PVGA1A chipset and 256 KB of RAM.
          It supports one super VGA mode: 58h, ie. 800x600x16, and for this needs a multisync monitor.
          I suspect that with SW1 set to standard VGA that mode is unavailable.
          I recall that's not true. I was using standard VGA setting and I was still able to put SVGA in Windows 3.1. I could test this later to confirm.

          Comment


            #6
            Any mode with more than 480 lines requires a "multisync"/SVGA monitor. So either the SVGA mode you were using in Windows 3.1 was 640x480, or the Windows driver is ignoring whatever the DIP switch setting is (if you had it set to standard VGA).
            Offering a bounty for:
            - A working Sanyo MBC-775 or Logabax 1600
            - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

            Comment


              #7
              Originally posted by Trixter View Post
              Any mode with more than 480 lines requires a "multisync"/SVGA monitor. So either the SVGA mode you were using in Windows 3.1 was 640x480, or the Windows driver is ignoring whatever the DIP switch setting is (if you had it set to standard VGA).
              Under Windows 3.0 I vaguely recall getting a special hacked driver so I could display 800x560 using my standard VGA equipment.

              Seemed to work, not sure why it wasn’t the full 600 lines though.
              but the image on screen seemed tall and squished

              Comment


                #8
                Originally posted by rmay635703 View Post
                Under Windows 3.0 I vaguely recall getting a special hacked driver so I could display 800x560 using my standard VGA equipment.

                Seemed to work, not sure why it wasn’t the full 600 lines though.
                but the image on screen seemed tall and squished
                Maybe the refresh rate was lowered to accomodate higher vertical resolution. That's where the hacking came in. It was probably 560 lines because the original NEC M* and M* II was only rated up to 560 lines. Iirc Sony was the very next company to release a m* and there's could do 600 lines.

                Nothing is absolutely etched in stone. Everything has some variability. Back in the day people were hacking CGA monitors to accept EGA signals. Not every monitor could do it though.

                Comment


                  #9
                  Originally posted by Trixter View Post
                  Any mode with more than 480 lines requires a "multisync"/SVGA monitor. So either the SVGA mode you were using in Windows 3.1 was 640x480, or the Windows driver is ignoring whatever the DIP switch setting is (if you had it set to standard VGA).

                  Oh, I forgot to mention the main thing. I am not actually bothered about the SVGA thing in windows but in dos, when multisync option is set, none of my semi-modern VGA screens are able to view that signal even though they can go lower than 60hz refresh rate hence this makes me wondering what kind of weird non-standard resolution multisync is producing here.

                  Comment


                    #10
                    I have a similar card - 8-bit, based on PVGA1A, with FCC id: DBM5UEPS2V00001, apparently Philips OEM variant.
                    Connected it to a typical SVGA monitor, and did some tests...

                    SW1 set to "standard VGA" - all modes work as expected, except for 58h (800x600x16) where monitor goes into power saving mode

                    SW1 set to "multifrequency":
                    - text mode - monitor gets out of sync, measures the frequencies as 27.9 kHz / 62 Hz
                    - 200-line graphics modes - 31.5 kHz / 62 Hz
                    - 350-line graphics modes - 31.5 kHz / 62 Hz
                    - 480-line graphics modes - 31.5 kHz / 60 Hz

                    I don't understand it... perhaps this way it's supposed to be more compatible with CGA/EGA? You know, they are 60 Hz, and VGA displays 200- and 350-line modes at 70 Hz, causing problems with some timing-sensitive software.
                    But why such a weird frequency for text mode?

                    Comment


                      #11
                      Originally posted by 2icebitn View Post
                      Maybe the refresh rate was lowered to accomodate higher vertical resolution. That's where the hacking came in.
                      Exactly.
                      Search for "svgabg55.zip", run VGADEMO.EXE -> Tweak16 -> 800x600x16
                      Yes, even a plain VGA can be tweaked into 800x600, but the frequencies are 29.3 kHz / 45 Hz, making it pretty much useless.

                      Comment


                        #12
                        Originally posted by Xacalite View Post
                        I have a similar card - 8-bit, based on PVGA1A, with FCC id: DBM5UEPS2V00001, apparently Philips OEM variant.
                        Connected it to a typical SVGA monitor, and did some tests...

                        SW1 set to "standard VGA" - all modes work as expected, except for 58h (800x600x16) where monitor goes into power saving mode

                        SW1 set to "multifrequency":
                        - text mode - monitor gets out of sync, measures the frequencies as 27.9 kHz / 62 Hz
                        - 200-line graphics modes - 31.5 kHz / 62 Hz
                        - 350-line graphics modes - 31.5 kHz / 62 Hz
                        - 480-line graphics modes - 31.5 kHz / 60 Hz

                        I don't understand it... perhaps this way it's supposed to be more compatible with CGA/EGA? You know, they are 60 Hz, and VGA displays 200- and 350-line modes at 70 Hz, causing problems with some timing-sensitive software.
                        But why such a weird frequency for text mode?
                        But CGA or 200-line EGA is 15.7 Khz and 350-line EGA is 21.8 kHz so I don't think EGA monitor could stretch into 27Khz

                        Comment


                          #13
                          Originally posted by musicforlife View Post
                          But CGA or 200-line EGA is 15.7 Khz and 350-line EGA is 21.8 kHz so I don't think EGA monitor could stretch into 27Khz
                          ATI EGA Wonder would output 640 by 480 graphics modes and also had text formats with many, many columns. Needs a multi-sync monitor and I presume a higher kHz. I can't find a source detailing the signal specifics for this.

                          Comment


                            #14
                            Originally posted by musicforlife View Post
                            But CGA or 200-line EGA is 15.7 Khz and 350-line EGA is 21.8 kHz so I don't think EGA monitor could stretch into 27Khz
                            Exactly.
                            It would be logical for the card to output 15.7 kHz for 200-line modes, 21.8 for 350-line, and 31.5 for 480-line. And 27.9 kHz might be logical for 400-line, ie. VGA text modes.
                            But this card doesn't behave this way.

                            BTW: you mentioned some success with the 800x600 mode - what kind of monitor were you using?

                            Comment


                              #15
                              Originally posted by Xacalite View Post
                              Exactly.
                              It would be logical for the card to output 15.7 kHz for 200-line modes, 21.8 for 350-line, and 31.5 for 480-line. And 27.9 kHz might be logical for 400-line, ie. VGA text modes.
                              But this card doesn't behave this way.

                              BTW: you mentioned some success with the 800x600 mode - what kind of monitor were you using?
                              Under Windows 3 I used an old plain VGA Tandy VGM monitor with 800x560 using a generic VGA card

                              I never noticed any real flicker and used the screen several years after we sold our name brand machine to get a generic tower.

                              Comment

                              Working...
                              X