Dumb question -- does adding VRAM to a Nubus video card or Mac onboard video make video rendering faster? Or does it just give you more colors and larger screen support?
VRAM - more speed, or just more colors?
- Thread starter misterg33
- Start date
I have not done the testing in practice.
In theory, it depends on the card. While one would expect it to just give one more capacity and therefore more colors and screen size/resolution, there is a way it could improve performance.
If the added memory actually widens the data bus (goes from 32 bits wide to 64 bits wide, e.g.) there are some fancy muxing/demuxing tricks that video cards can do with memory to gain performance.
I don't know whether any of them behave that way in practice. It makes the design more complicated, and for un-upgraded cards, the mux/demux circuitry is just sitting there (expense) doing nothing unless the upgrade is installed.
In theory, it depends on the card. While one would expect it to just give one more capacity and therefore more colors and screen size/resolution, there is a way it could improve performance.
If the added memory actually widens the data bus (goes from 32 bits wide to 64 bits wide, e.g.) there are some fancy muxing/demuxing tricks that video cards can do with memory to gain performance.
I don't know whether any of them behave that way in practice. It makes the design more complicated, and for un-upgraded cards, the mux/demux circuitry is just sitting there (expense) doing nothing unless the upgrade is installed.
No increase in rendering/blitting performance that I know of. Just increased resolution and color depth.
More pixels/greater workspace = better user efficiency in task performance = higher speed.
So yes, indirectly, I'd say adding VRAM increases workflow efficiency . . . or it just looks prettier.
So yes, indirectly, I'd say adding VRAM increases workflow efficiency . . . or it just looks prettier.
Normally, adding more VRAM will enable higher resolutions and/or bit depths. But in my experience with vintage Macs, a switch to higher bit depths like from B&W to 8-bit (256 colors), or from 8-bit to 16 or 24, tends to reduce machine performance. The same is true for the switch to higher resolutions.
IF you add more VRAM but make no changes to bit depth or resolution, I’ve not seen any noticeable performance boost myself.
Also note that even the fastest NuBus video card is not a speedy as Quadra onboard video.
IF you add more VRAM but make no changes to bit depth or resolution, I’ve not seen any noticeable performance boost myself.
Also note that even the fastest NuBus video card is not a speedy as Quadra onboard video.
AFAIK, the only NuBus Card to ever outperform onboard video (which is the rough equivalent of PDS video) would be the bit bangin' monster that @Melkhior developed.
NuBus Cards, VRAM, high resolutions and color depths ARE NOT for greater speed out of a computer, ever. High resolution and color depth make the system work harder to fill the larger, deeper color frame buffers. But there are handsome tradeoffs involved.
The gain in performance would be at the user level's I/O, interacting with hardware and software. The user would be the ultimate limiting factor when it comes to performance of a SYSTEM outside of things like rendering when that became a thing. Performance improvement is seen in the user working faster/more efficiently within many applications, where larger amounts of information on screen interacts with the Mk.1 eyeball. Some such would include:
- Graphics programs of course, less time scrolling across a large document speeds things up very nicely, color depth needed as well
- Desktop Publishing, where the performance hit of filling a full or two page display's frame buffer pays off tremendously, even 1bit on 128K
- Spreadsheets as well are much faster to use when more cells are visible, especially if two related cells can't be seen without scrolling.
- Database - same deal, putting a larger data set onscreen pays big dividends
Can't think of incremental or even great improvements or deficits in the inner workings of a SYSTEM. The rubber meets the road at the user level.
p.s. When folks talk about accelerated graphics cards, they fail to realize that it's QuickDraw that's accelerated. Users of the apps above throw acceleration right out the window when they press the spacebar and use the hand too to scroll. Page navigation keys and manipulating the scroll bars themselves are accelerated in QuickDraw. The hand tool is not.
NuBus Cards, VRAM, high resolutions and color depths ARE NOT for greater speed out of a computer, ever. High resolution and color depth make the system work harder to fill the larger, deeper color frame buffers. But there are handsome tradeoffs involved.
The gain in performance would be at the user level's I/O, interacting with hardware and software. The user would be the ultimate limiting factor when it comes to performance of a SYSTEM outside of things like rendering when that became a thing. Performance improvement is seen in the user working faster/more efficiently within many applications, where larger amounts of information on screen interacts with the Mk.1 eyeball. Some such would include:
- Graphics programs of course, less time scrolling across a large document speeds things up very nicely, color depth needed as well
- Desktop Publishing, where the performance hit of filling a full or two page display's frame buffer pays off tremendously, even 1bit on 128K
- Spreadsheets as well are much faster to use when more cells are visible, especially if two related cells can't be seen without scrolling.
- Database - same deal, putting a larger data set onscreen pays big dividends
Can't think of incremental or even great improvements or deficits in the inner workings of a SYSTEM. The rubber meets the road at the user level.
p.s. When folks talk about accelerated graphics cards, they fail to realize that it's QuickDraw that's accelerated. Users of the apps above throw acceleration right out the window when they press the spacebar and use the hand too to scroll. Page navigation keys and manipulating the scroll bars themselves are accelerated in QuickDraw. The hand tool is not.
Last edited:
NuBusFPGA: HDMI on NuBus Macs
Hello, I've mentioned my crazy project of interfacing a FPGA (board) with a NuBus Mac in another thread. I'm opening a new dedicated thread as there is a significant update now: This show the naked PCB on the left, the populated version without the required daughterboard in the middle, and the...
68kmla.org
As everyone has mentioned so far, adding VRAM generally increases the maximum number of colors and resolution only. However, on accelerated NuBus/PCI/AGP cards, adding VRAM can speed up graphics. For example, the Apple 8*24 GC card can vastly speed up offscreen graphics with additional VRAM.
"When a drawing operation that involves a GWorld occurs, GC QuickDraw immediately caches the complete GWorld structure in the card's memory if the structure has not yet been cached and if sufficient memory is available. (The card's optional DRAM kit is an important addition for applications that work with large GWorlds.) When CopyBits is called to display the results, the transfer of pixels to the screen driven by the 8*24 GC card is therefore really fast because there is no NuBus transfer. Even displaying the image into other monitors benefits, especially when the other cards can accept block transfers. Drawing operations to and from GWorlds can be executed in parallel. This is not the case when drawing to or from old-style offscreens"
"When a drawing operation that involves a GWorld occurs, GC QuickDraw immediately caches the complete GWorld structure in the card's memory if the structure has not yet been cached and if sufficient memory is available. (The card's optional DRAM kit is an important addition for applications that work with large GWorlds.) When CopyBits is called to display the results, the transfer of pixels to the screen driven by the 8*24 GC card is therefore really fast because there is no NuBus transfer. Even displaying the image into other monitors benefits, especially when the other cards can accept block transfers. Drawing operations to and from GWorlds can be executed in parallel. This is not the case when drawing to or from old-style offscreens"