SuperMac Spectrum/24 Project

[MacOSMonkey]

As far as I know, there isn't any way to do 720p on that board. There are multiple factors at work.

Problem 1:
Regarding the Slot Manager, video cards on the Mac have to have sRecs for the target resolution/configuration. IIRC, the Spectrum/24 Series III supported resolutions of 1024x768 (Sony 60Hz Trinitron), 768x576 (PAL/MultiSync) and 640x480 (Apple/NTSC). Later ROMs added support for Apple/SuperMac 16" @ 832x624 and Apple 12" @ 512x384. There are also sRecs for the stock virtual desktops, including 2048x1536 and 4096x1536 (but within the context of 1024x768). Even with custom timing in SuperVideo, I think it still had to adhere to one of the stock resolutions. But, I will think about that one some more - it's from 30 years ago. IIRC, SuperVideo built and installed custom sRecs into slot PRAM, and I will try to play around here with some of my boards (if they still work) to see if I can recall anything else.

I think the oscillators for 16" mode were: 57.28Mhz (Apple/75Hz) and 55Mhz (SuperMac 16"/75Hz). The timings were slightly different (even though the monitors were the same). There was a philosophy of anti-mix-and-match.

Apple 12" mode was 15.67Mhz...I think (and I don't think virtual desktops worked on that monitor).

Problem 2:
As above, the default config for the original Spectrum/24 was 64Mhz 1024x768/60Hz and Spectrum/24 Series III was 80Mhz and 1024x768/75Hz (primary config). With custom mode, even if the oscillator already exists on the board, you still have to put a duplicate in the socket in order to use it with a custom config...and the board has to detect it. But, I don't think the board could detect custom oscillators beyond 64Mhz (or thereabouts). So, even if you were to install an 80Mhz oscillator in the extra socket, the board probably wouldn't detect it because it would be off the top end (even though there is one on the board already - not usable for custom). And, you can tell when detections fails -- the oscillator does not show up in the SuperVideo custom config screen.

Problem 3:
If you have a later ROM that adds 12" and 16" support, I don't think the later versions even supported custom configs via SuperVideo. They were too problematic. Now that I'm thinking of it, early versions of SuperVideo had a feature called "Lock Menubar," which eventually went away - maybe related. The point of Lock Menubar was to try to keep the menu on the screen while in Virtual Desktop mode, but it didn't work very well and also caused problems with custom configs. So, if you have an original/1.0 ROM, then custom configs probably still work. Otherwise, they won't.

Also, FYI, cable sense didn't work for every mode, which is why some of the SuperMac boards have a rotating startup config. If the board sees cable sense, it uses that -- especially on later boards with 1152x870. Failing that, The board will cycle and failing that, the user can choose the config in SuperVideo.

Anyway - that's the best I can do for now. I hope the additional detail helps. As above, I see what else I remember while experimenting with my boards.

 

[Trash80toHP_Mini]

OOPSIE!!!! Mistyped/mistook/half asleep: gave up on 720p as unsupportable. Target Resolutions are now:
854 x 480 WVGA AKA FWVGA spec'd on previous page
1024 x 600 WSVGA
720 x 480 480p which is not a VGA Standard IIRC

1024 x 600 might work on modern displays? Dunno, but that's the highest wide screen resolution I've found that might work. Have to check to see if it's supported as a pre-set on a couple of my displays.

854 x 480 sounds like the real deal if that's truly the resolution of progressive DVD. I'd thought it was 480p, but I've been proven to be very, very wrong on a lot things, very cool, new stuff learned that way.

I'll have to dig the IIfx out so I can test this card in the IIcx. Gotta replace the Tantalum TNT Charge in the pet IIfx before I fire that one up again!

 

[MacOSMonkey]

What version is your ROM? 1.0? Also, I will take a look at SuperVideo on my boards and try to remember some more about custom configs -- I think I have some spare oscillators around somewhere, but, again, I think you are restricted to choosing one of the stock resolutions, and only if you have the 1.0 ROM of Spectrum/24 Series III.

 

[Trash80toHP_Mini]

Yep. ROM 1.0 on board, at least according to what I posted when this thread was a new update of an older version of the topic. Will the Series III run from my first release Spectrum/24 1.0 ROM?

I had the impression that SuperMac was out to support UNIX workstation resolutions.

edit: wow, the ten year old link from p.1 is still up! That's the bundle I bought.

SuperMac Spectrum/24 Apple Mac NuBUS Video Card wManual | #171272057

SuperMac Spectrum/24 Apple Macintosh NuBUS Video Card w/ manual and SOFTWARE ! Here is a rare piece of Apple Macintosh History. The SuperMac Spectrum video display card was the first 24 bit, High reso

www.worthpoint.com

 

[MacOSMonkey]

Is that the only board you have, or do you also have a Spectrum/24 Series III? What is the date on the ROM?

 

[Trash80toHP_Mini]

ROM's 1.0 (c)1989, I think this is the only SuperMac board I have, I'm pretty much a Radius collector, Macs are hosts. First one was an SE/Radius16/CoPro for CAD/CAM production in my sign business. Second was IIx/Rocket, first color TPD was Radius and the VidCard would almost certainly have been as well, but don't recall that offhand.

Figured Spectrum/24 was intended to support CAD, which was just coming to Micros and the UNIX workstations that ran it. My read of the docs led me to believe the card would output custom resolutions, limited to the the capabilities of RAMDAC of course.

Theory would be that the marketing and hardware folks didn't know what new resolutions and freqs would be appearing in DTP/CAD workstations and CRT technology development that SuperMac might employ over the next year or two?

 

[Phipli]

I'm a little surprised because if I was writing a manual for a card that could only do custom timings for 5 or so resolutions, I'd list them in the manual as such. It doesn't say you're limited to those resolutions. And given you write the resolutions and timings to the card then restart why wouldn't the declaration ROM just look up what resolutions were written to it?

 

[Phipli]

My bad, it does say "select the resolution".

Ah well.

 

[Trash80toHP_Mini]

Context? Page/paragraph for that in the manual?

User manual info and presentation would be the tail trying to keep up with the moof. Manual might not reflect limitations that come up for the shipping product or reflect back doors that might have been left ajar into features outlined in project development.

Biggest question here would be where the custom resolution config setup is stored? WAG would be on disk for lookup or as a System folder Init? I'd almost bet a shiny nickle on it being uploaded to the likes of PRAM on the card acting as an extension to DeclROM? IIRC there's no trickle power on NuBus to retain a PRAM setup on card?

If nothing else there should be a backup copy on disk for the situation that a card is removed and replaced?

 

[Phipli]

Context? Page/paragraph for that in the manual?

From your photos of the Spectrum 24 manual. I was paraphrasing the listbox in saying select a resolution sorry, to be clear.

 

[Trash80toHP_Mini]

My take on that would be that what you're seeing a list of stock resolutions and any custom configs already present. Input parameters for adding to that list via Save As would be a reasonable interpretation of that graphic, no?

edit: yep, see steps 2 & 7, had that a bit backwards. Modification of an existing resolution and saving it to a new entry to the list would be procedure for doing a custom resolution?

 

[Trash80toHP_Mini]

@MacOSMonkey I think all the info I have on this card is in the first post of the thread.

If nothing else, we should be able to do standard resolutions tweaked for 60Hz output on current displays, no? Still holding out hope for a custom, wide screen, auto-scaling preset output for a 1080p display.

 

[MacOSMonkey]

I think the resolutions are going to be tied to the default sRec resolutions in the ROM. You can create custom timings for the stock resolutions, but depending on the resolution you choose in SuperVideo for the custom config, there will probably be some amount of H or V screen clipping on monitors that have different resolution requirements.

 

[Trash80toHP_Mini]

Drivers for custom resolutions can be loaded from disk at startup, no? DeclROM is required to contain baseline drivers for a Nubus VidCard to act as the "startup screen" for the Macintosh II series, but additional drivers and resolutions can be loaded from disk. Baseline resolutions would be usable under the Monitors Control Panel. As I understand it, replacements for "Monitors" that shipped with VidCards like SuperVideo appended new capabilities outside the limitations of the baseline resolutions supported by the Monitors Control Panel. Custom resolutions for Spectrum/24 would fit into that category.

I'm going off vague recollections from my reading of documentation in the "Designing Cards and Drivers" series for DeclROM here. The critical point would be where the "My Monitor" custom configuration is stored, from where and how it is loaded into System. If extensions are installed at boot, the CPU can load anything required from PRAM contents into a VidCard's frame buffer, no? I see no reason whatsoever for SuperMac to block non-standard resolution output to RAMDAC within its capabilities in firmware or how such might even be done?

Drivers expand upon capabilities defined in DeclROM, which exists primarily for detection under the Slot Manager and to bring cards up to where drivers can be loaded from disk.

No expert, but I don't see any limitation from the software side that would preclude ignoring DeclROM entirely in terms of driver support. This would be similar to VidCards for the SE PDS. As there's no DeclROM in SE non/pre- "Slot Manager" architecture. Drivers are loaded from disk as Inits/Extensions enabling the CPU to load a VidCard's frame buffer for the external display at startup.

ISTR there being mention of a single NuBus card requiring drivers loaded from disk for basic function?

I might add the double-boot requirement for Rocket function to that. However that has to more to do with necessity for copying system ROM into RAM on the Rocket per Radius licensing for its use.

 

[Trash80toHP_Mini]

Had yet another flood in the apartment. One good thing has come of it though, Spectrum/24/1.0 now resides in the NuBus Adapter of a recapped IIsi for some quality playtime!

The quest for scalable widescreen output continues . . . maybe.

Now to find the VGA Association's resolution/timings spreadsheet. Meanwhile, scoured Wikipedia for some possibilities:

720 x 480 480p not a VGA Standard, lower res and not particularly widescreen, so not targeted, last resorted?

854 × 480 (FWVGA)
FWVGA is an abbreviation for Full Wide Video Graphics Array which refers to a display resolution of 854 × 480 pixels. 854 × 480 is approximately the 16:9 aspect ratio of anamorphically "un-squeezed" NTSC DVD widescreen video and is considered a "safe" resolution that does not crop any of the image. It is called Full WVGA to distinguish it from other, narrower WVGA resolutions which require cropping 16:9 aspect ratio high-definition video (i.e. it is full width, albeit with a considerable reduction in size).

The 854 pixel width is rounded up from 853.3:
480 × 16⁄9 = 7680⁄9 = 8531⁄3.
Since a pixel must be a whole number, rounding up to 854 ensures inclusion of the entire image.[75]

960 × 540 (qHD) Note: qHD is quarter HD; QHD is quad HD
qHD is a display resolution of 960 × 540 pixels, which is exactly one-quarter of a Full HD (1080p) frame, in a 16:9 aspect ratio.

1024 × 576, 1024 × 600 (WSVGA)
The wide version of SVGA is known as WSVGA (Wide Super VGA or Wide SVGA), featured on Ultra-Mobile PCs, netbooks, and tablet computers. The resolution is either 1024 × 576 (aspect ratio 16:9) or 1024 × 600 (128:75) with screen sizes normally ranging from 7 to 10 inches. It has full XGA width of 1024 pixels. Although digital broadcast content in former PAL/SECAM regions has 576 active lines, several mobile TV sets with a DVB-T2 tuner use the 600-line variant with a diameter of 7, 9 or 10 inches (18 to 26 cm).

Lets see if I can get this to work on the first rev. card. Sure hope the setup can be wrung out and imported into the later versions. Crystal spec calculated by SuperVideo would be worth a try. ROM manipulation just might be possible.

 

[MacOSMonkey]

As above, I don't think you can use custom resolutions and are limited to the ones currently provided by the card. You can use custom timings with those built-in resolutions, but you can't change the H & V settings. The configuration process starts by selecting an existing resolution to customize. You will also not be able to use any configuration that has a custom oscillator higher than about 64Mhz, and if you want to create a custom config that uses the same frequency as a built-in oscillator, you will have to put that same frequency oscillator in the custom socket.

 

[Trash80toHP_Mini]

I don't read it that way at all, the manual clearly states differently:



I think the misunderstanding here stems entirely from SuperMac's unfortunate decision to use their stock 19" resolution/timings in illustrating the card's capabilities for Defining a Custom Monitor Configuration per the title of the section.

The very first thing defined is the custom resolution in pixels wide x pixels vertical and everything else follows from there per the formulas as detailed.

Page 60 states that the reference crystal can be as high as 104Mhz, with a Pixel Rate Divider factor of 16.

This should be fun, we'll see what happens.

 

[MacOSMonkey]

I don't think the card detects oscillators above ~64Mhz (but it might go slightly higher as a slop factor). And, if the card doesn't detect the oscillator, configs that use it won't work - maybe similar to the issue of not having a custom oscillator installed (black screen).

In terms of resolution, SuperVideo lets you choose an existing sRec for the OS screen resolution and you can set custom timing parameters for that configuration, assuming the extra socket has a custom oscillator within the range of max detection.



These are my best recollections from 30 years ago.

 

[Phipli]

Come on folks, would someone just test it? My rig isn't working atm due to a poorly PSU, but this is just going around in circles. It isn't going to be solved by discussion. I have a watch on this thread because I'm interested in the topic, but I've had two weeks of notifications that are just a hypothetical argument.

I also note people are switching between talking about the original spectrum/24 and the "Series III" without missing a beat. Take care to be specific given I read the Spectrum/8 Series III manual as excluding custom setups. It is only mentioned wrt what seems to be legacy support in the driver for older cards. We have two manuals for not the right card and are arguing over which is less wrong.

 

[LaPorta]

I’ll throw my hat in the ring: glad I found this thread since I have a Spectrum/24 card in my IIfx, and I didn’t even know there were drivers! I installed one, and now I can change resolutions. I thought it would only output 640x480.

There really are no markings on the card; how do I identify which one I have?