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Cloudschatze
March 30th, 2012, 12:49 PM
Does anyone have any benchmark stats or anecdotal information regarding the performance of 8/16-bit VGA cards in 8-bit slots? I've tested a number of such cards in an accelerated Tandy 1000 TL/2, and am hitting a bottleneck that seems to be no respecter of chipset. Cirrus Logic, Paradise, Trident, and Tseng-based cards have been tried, and all display the same number of frames per second, per the "3DBench" utility. Perhaps 8-bit VGA is simply slow, and that's all there is to it? Might it be worth trying additional chipsets (ATI)?

I will note that the Tseng and Cirrus Logic cards (the latter of which I am currently using) are the only ones of those tested that don't produce colored "snow" artifacts during fast palette-cycling effects.

Chuck(G)
March 30th, 2012, 01:19 PM
8 bit ISA is slow--adding the higher memory requirement of VGA (more lines, more colors, more pixels) is probably the big limitation.

Cloudschatze
March 31st, 2012, 11:44 AM
Thanks, Chuck. I figured as much.

RBARDY
April 1st, 2012, 06:31 PM
When it comes to video speed you can go crazy i saw a 16 bit isa vga card that was new but very cheap and was selling like hotcakes but the frame speed was slower than a old ega card on the other hand i tried a vga card with a tseng 4000 chip in a 486 board with the bus speed set at 8 mz giving 2200 fps at 10 mz bus speed 2800fps at 12.5 mz bus speed 3400fps that board went to 16mz but the scsi cont could not take it

Unknown_K
April 1st, 2012, 06:56 PM
8 bit ISA video cards (256K RAM) are preety slow for any gaming, you might as well just deal with CGA or EGA on an XT.

http://www.pcguide.com/ref/mbsys/buses/funcBandwidth-c.html

The whole 8 bit bus can move 7.9mb/sec (at 8mhz) in theory BEFORE wait states come into play reducing speed like a rock.

twolazy
April 2nd, 2012, 03:11 AM
Fastest card I have used on my 5150 is my Wyse ET4000AX 1mb. Its loads faster then my 2 trident cards. I only have a few video cards that can do 8 bit sadly. ATM I have the 5162's IBM CGA card in my 5150, the wyse is in my 5162. Its not exactly a common card though. It was mainly used for CAD and desktop publishing, but its a gaming monster!

michal
April 2nd, 2012, 05:49 AM
i tried a vga card with a tseng 4000 chip in a 486 board with the bus speed set at 8 mz giving 2200 fps

The question is: 2200 fps of what ? Surely not full frame updates (assuming the frame is a mode 13h bitmap @ 64KB the bus would need 137,5MB/s). Probably just some benchmark measuring x frames per second of whatever that benchmark is doing. Perhaps you are referring to the same "3dbench" benchmark as the OP ?

Cloudschatze
April 2nd, 2012, 11:23 AM
The question is: 2200 fps of what ? ... Perhaps you are referring to the same "3dbench" benchmark as the OP ?

Probably not. 3DBench reports 6.6 FPS with my Tandy setup. A score of 2200+ FPS with this utility would be nonsensical.

Chuck(G)
April 2nd, 2012, 11:35 AM
As long as we're not talking about using some fancy on-board acceleration, isn't the bog-plain Hercules mono card just about as fast as you can get? Yes, you can buffer screen frames with a VGA, but that doesn't help you with overall bandwidth.

Cloudschatze
May 5th, 2014, 11:15 AM
For whatever it's worth, by utilizing the DRAM-refresh-adjusting "SPEED.COM" utility, 3DBench now reports 7.4 FPS in the VGA-hosting Tandy, up from the 6.6 FPS mentioned earlier.

Now we're playing with power!

In all seriousness, it does make a difference.

dorkbert
May 5th, 2014, 08:24 PM
... went to 16mz but the scsi cont could not take itfor that kind of bus clock, you want an UltraStor card...

pearce_jj
May 6th, 2014, 11:22 AM
Just to mention, 8-bit ISA generally runs at about 4.77MHz equivalent. AT machines introduced 'ZWS' signal (on line B8 ) to enable 8MHz operation. Sadly the 1000TL doesn't have this signal.

Great Hierophant
May 6th, 2014, 08:30 PM
Just to mention, 8-bit ISA generally runs at about 4.77MHz equivalent. AT machines introduced 'ZWS' signal (on line B8 ) to enable 8MHz operation. Sadly the 1000TL doesn't have this signal.

The TL has Wait State cycle setup options for Internal Memory, External Memory (Expanded Memory), CPU I/O Cycle, DMA Cycle, 16-bit Video. The defaults are 0, 3, 3, 1,1. Could the CPU I/O Cycle time be the equilavent?

pearce_jj
May 6th, 2014, 11:08 PM
The TL has Wait State cycle setup options for Internal Memory, External Memory (Expanded Memory), CPU I/O Cycle, DMA Cycle, 16-bit Video. The defaults are 0, 3, 3, 1,1. Could the CPU I/O Cycle time be the equivalent?

That's interesting: I read that as

0 - System board RAM (full 8MHz)
3 - ISA bus connected memory cycle (VGA, EMS, peripherals providing memory-mapped IO) - approx 4.5MHz equivalent
3 - ISA bus connected IO cycle (IO devices like HDD, FDD, serial etc) - approx 4.5MHz equivalent
1 - Not sure on this as the DMA controller always runs at 4.7MHz is my understanding, and usually doesn't support compressed timing (without the wait state)
1 - Wait-state for on-board video RAM

If that is correct, so changing 'External Memory' (if you can) should see an improvement in performance, since video is memory-mapped.

Cloudschatze
May 6th, 2014, 11:31 PM
I've spent a significant amount of time testing those settings, and have seen absolutely no change or improvement with them. Jeffrey Hayes mentioned something to the same effect decades ago. Furthermore, these settings are neither mentioned in, nor correspond to, anything in the Technical Reference manual. They might serve as additional wait states to those mentioned in the tech ref., assuming the settings really do anything at all.

In any event, here's a video that demonstrates the VGA frame-rate of my TL/2 system fairly well. I'm pretty biased, but all things considered, it's a remarkable feat. :)


https://www.youtube.com/watch?v=yVREcM4xUOs

sergey
May 20th, 2014, 10:10 PM
8 bit ISA video cards (256K RAM) are preety slow for any gaming, you might as well just deal with CGA or EGA on an XT.



Depends on the game. Many late 80's early 90's games didn't require fast graphics. Most of them would not redraw the entire screen for every frame, some will (e.g. Doom), but they would use low resolution modes, and some other tricks.




http://www.pcguide.com/ref/mbsys/buses/funcBandwidth-c.html

The whole 8 bit bus can move 7.9mb/sec (at 8mhz) in theory BEFORE wait states come into play reducing speed like a rock.

Don't trust that table. These guys apparently were trying to be smart and divided 8,000,000 Hz by 1024 something, or were trying to take memory refresh into account.... They could have been even smarter and could try dividing 8,000,000 Hz by 1048576 bytes, and still it won't be correct. Not even close to be correct.

8 MHz ISA bus frequency refers to 8 MHz 80286 processor controlling that bus (original IBM AT is the reference for ISA). Now each bus cycle on 80286 takes at least 4 CPU clock cycles.

With 16-bit ISA the transfer rates will potentially get close to 4 MT/s (MT/s for mega transfers per second), or about 3.8 MB/sec. That is if we don't count 1 wait state which gets inserted by default (unless the card asserts /0WS).

8-bit ISA number (7.9 MB/sec) is even more wrong. Most (if not all) 8-bit cards will have a mandatory 4 wait states inserted. So that it will take 8 CPU clock cycles for a single bus cycle. That is 1 MT/s.

Edit: With that being said, many Turbo XT clones, especially early ERSO ones and similar didn't bother inserting more wait states when board was working in Turbo mode. (Some boards had jumpers that allowed selecting 2, 3, or 4 wait states, instead of the default 1, but that regardless of Turbo mode). With such Turbo XT 8 MHz board you could actually get close to 2 MT/s (less memory refresh penalty). Many newer 8-bit cards will work just fine in such systems. My 8-bit Paradise VGA and Trident VGA are pretty stable even at 13.333 MHz.

Chuck(G)
May 20th, 2014, 10:18 PM
You can easily see this in some 9-track tape controller boards. Many formatters can transfer at 1MB/sec and there's not an 8 or 16 bit ISA card that can keep up with this without using private memory. Thank heavens for IRGs.

I was working on one and wanted to see if there was a way around bottleneck. Nope--DMA is even worse.