Doom vs Heretic VGA performance difference

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Re: Doom vs Heretic VGA performance difference

Postby canthearu » 2019-1-12 @ 03:31

First things first, I have found that ISA video cards are somewhat slower in the pentium system than they are in my 386. Probably because the bus speed is fixed to the AT spec, rather than being programmable.

Test System:
Pentium MMX 233 (I overclocked a 200mhz CPU to match the OPs Processor)
Azza PT-5IT motherboard.
64meg RAM

I have copied the OP's benchmark settings to make results as comparable as possible.

OAK 067 SVGA - 512KB
Quake - 22.7 fps
Doom - 15.5 fps (2134 gameticks in 4816 realticks)
Vidspeed 4.0 (write) - 1026KB/s at 8-bit, 2044KB/s at 16-bit, 2431KB/s at 32-bit

Notes: This card is no match for the ET4000AX, but should be fast enough for early DOS systems. There are certainly a LOT worse, as you will see below.

Tseng ET4000AX SVGA - 1024KB
Quake - 30.4 fps
Doom - 26.2 fps (2134 gameticks in 2849 realticks)
Vidspeed 4.0 (write) - 1832KB/s at 8-bit, 3605KB/s at 16-bit, 4242KB/s at 32-bit

Notes: The ET4000AX is the real deal for ISA based systems. When tested on my 386, vidspeed reached 7772KB/s performance with 32bit transfers. This card, or cards that perform similarly are exactly what you want for fast 386 or ISA only 486 systems.

Trident TVGA 8800CS - 8 bit ISA - 256KB
Quake - 9.4 fps
Doom - 9.4 fps (2134 gameticks in 7953 realticks)
Vidspeed 4.0 (write) - 720KB/s at 8-bit, 730KB/s at 16-bit, 720KB/s at 32-bit

Notes: This card is VERY slow, but would work fine on an XT, and looks like it can take TTL monitors in addition to VGA monitors (not 100% sure, I don't have any to test)

HP D1180A - Paradise PVGA1A - 256KB - 8-bit mode
Quake - 13.5 fps
Doom - 11.9 fps (2134 gameticks in 6285 realticks)
Vidspeed 4.0 (write) - 847KB/s at 8-bit, 1047KB/s at 16-bit, 1130KB/s at 32-bit

Notes: This came from my Vectra CS, and the display is a little bit buggy when used in other computers, but it is a good example of an early VGA card. Definitely better than the trident

HP D1180A - Paradise PVGA1A - 256KB - 16-bit mode
Quake - 22.4 fps
Doom - 11.9 fps (2134 gameticks in 6287 realticks)
Vidspeed 4.0 (write) - 1005KB/s at 8-bit, 2001KB/s at 16-bit, 2306KB/s at 32-bit

Notes: Switching this to 16-bit mode, increases performance in quake a significant amount, but doom performance didn't shift. It looks like doom only uses 8-bit writes when writing frames to video memory.

Geforce 2-MX 400 PCI - 64MB Memory
Quake - 53.1 fps
Doom - 94.1 fps (2134 gameticks in 794 realticks)
Vidspeed 4.0 (write) - 13342KB/s at 8-bit, 33300KB/s at 16-bit, 89043KB/s at 32-bit

Notes: if you have a PCI system, you absolutely must use a PCI card in it. Even the worst PCI card beats the crap out of any ISA card on these systems.
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Re: Doom vs Heretic VGA performance difference

Postby BinaryDemon » 2019-1-12 @ 04:45

Interesting results.

That Tseng ET4000AX SVGA - 1024KB is straight up killing it.

Makes me want to see a Tseng ET4000AX vs various VLB cards showdown.
Check out DOSBox Distro:

https://sites.google.com/site/dosboxdistro/ [*]

a lightweight Linux distro (tinycore) which boots off a usb flash drive and goes straight to DOSBox.

Make your dos retrogaming experience portable!
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Re: Doom vs Heretic VGA performance difference

Postby canthearu » 2019-1-13 @ 09:52

My VLB system isn't a particularly great example, but just for reference with vidspeed:

System Specs:
486DX-66
8meg RAM
S3 805 1Meg VLB Graphics card

Vidspeed L:
8-bit Transfers: 8325KB/s
16-bit Transfers: 16650KB/s
32-bit Transfers: 11100KB/s

8 and 16 bit transfers are as fast as normal memory writes on this system.
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Re: Doom vs Heretic VGA performance difference

Postby silikone » 2019-1-14 @ 15:11

Not a single ISA card that handles Doom better than Quake? Ouch.
Things should look really nasty for the latter with vid_mode 1, though.
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Re: Doom vs Heretic VGA performance difference

Postby Scali » 2019-1-17 @ 20:14

It's an interesting find, and reminds me of accelerated Amiga 1200 machines.
What we see here is that the 'clever' stuff of Mode X/Y only holds for slower machines. The big win of these modes is that you do not need a backbuffer in system memory, and copy it to the screen every frame. You can just render to a backbuffer in video memory, and flip the display.
That is all fine and good, because you save a lot of bandwidth writing to system memory, at the cost of a little extra overhead for having to toggle the bitplane registers a few times.
However, if you use a very fast machine, writing to system memory becomes a lot cheaper, so you no longer save time there, and the overhead for the bitplane operations remains, and starts working against you.

On Amiga you have a similar issue, because the Amiga uses a memory layout with true bitplanes, up to 8 bitplanes for 256 colour modes. Updating a single pixel requires writing to 8 individual positions in memory.
So instead, what you do is to write to a 'chunky' buffer in system memory, where the pixel bits are grouped together in bytes, just like mode 13h on VGA. You can read and write individual pixels very efficiently in that buffer. Once you're done rendering, you use the CPU to convert the buffer to 8 bitplanes on-the-fly, a process known as chunky-to-planar.
On slow Amigas, this chunky-to-planar was very costly, so generally you'd try to use graphics routines that would map well to the bitmap layout, and where you could use the blitter to accelerate drawing to the bitplanes. But on fast Amigas, doing advanced effects with textures and such was generally faster with chunky-to-planar.

Wolfenstein 3D and DOOM are similar in the sense that they try to exploit the Mode X/Y advantages of the hardware, and the game is specifically designed for that. Quake just 'bruteforces' things, but on the faster hardware, that balanced out better.
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Re: Doom vs Heretic VGA performance difference

Postby Scali » 2019-1-17 @ 20:23

canthearu wrote:Notes: Switching this to 16-bit mode, increases performance in quake a significant amount, but doom performance didn't shift. It looks like doom only uses 8-bit writes when writing frames to video memory.


Yes, good observation.
Wolfenstein 3D and DOOM render the screen in vertical columns of 1 pixel wide, because of the way the raycasting algorithm works.
A single pixel is 1 byte, so yes, it only writes bytes.
Quake probably copies the whole framebuffer from system memory to video memory with a bruteforce memcpy() routine like rep movsd or a similar clever thing that uses 32-bit or even 64-bit transfers (on Pentium you have a 64-bit data bus, the most efficient memcpy() there was to read and write with the FPU).
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Re: Doom vs Heretic VGA performance difference

Postby The Serpent Rider » 2019-1-18 @ 02:33

Wolfenstein 3D and DOOM render the screen in vertical columns of 1 pixel wide, because of the way the raycasting algorithm works.

Doom is not raycaster though.
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Re: Doom vs Heretic VGA performance difference

Postby Scali » 2019-1-18 @ 09:55

The Serpent Rider wrote:Doom is not raycaster though.


It is. It's basically Wolf3D with an added trick to add ceilings and floors, and walls at any angle. It casts rays through a 2D BSP tree.

Edit: actually, this seems to be a very contested issue, and it depends on who you ask.
Bottom line anyway: it renders in vertical columns, similar to Wolf3D, because of the limitations of the rendering algorithm.
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Re: Doom vs Heretic VGA performance difference

Postby The Serpent Rider » 2019-1-19 @ 15:16

I wonder if ISA bus overclocking can improve Doom performance significantly. Surely some cards can work at 16mhz.
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Re: Doom vs Heretic VGA performance difference

Postby Tiido » 2019-1-19 @ 16:04

Overclocked ISA significantly improves performance, but you'll have to be careful with some stuff like AWE64 which sooner or later get their PnP EEPROM corrupt (happened to be at 12MHz ISA). I was using a TVGA8900D, it also ran at 16MHz but occasionally showed corrupt graphics so not completely usable then.
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Re: Doom vs Heretic VGA performance difference

Postby Baoran » 2019-2-05 @ 11:25

Anyone knows if it actually matters what ram speed Tseng ET4000AX card has? I have seen cards with 80ns, 70ns and 60ns ram and I always wondered if it actually matters when it comes to performance.
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Re: Doom vs Heretic VGA performance difference

Postby The Serpent Rider » 2019-2-05 @ 12:04

Probably none or negligible.
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