Funny enough, don’t I recall pentium pro had a poor 16-bit performance? So a mmx200 might be faster?

Sphere478 wrote on 2024-06-01, 22:23:

Funny enough, don’t I recall pentium pro had a poor 16-bit performance? So a mmx200 might be faster?

MMX processors also have double the L1 cache.

Sphere478 wrote on 2024-06-01, 22:23:

Funny enough, don’t I recall pentium pro had a poor 16-bit performance? So a mmx200 might be faster?

Yes, it is faster as long as the code isn't optimal for the Pentium Pro.

Gmlb256 wrote on 2024-06-01, 15:59:

AlessandroB wrote on 2024-05-31, 19:52:

I can find a nice SBC with Pentium Pro 200 to fit in my amiga 2000, the inly problem is that the only graphic card i can fir will be a ISA card… that make the Pentium Pro inusable in mid DOS gaming??

Not unusable for DOS gaming but the experience isn't ideal because of the bottleneck of an ISA video card (especially with SVGA/VESA video modes) and performance hit that the Pentium Pro has with 16-bit and mixed codes where partial registers usage are common.

This is the correct answer. Ignore all the handwaving, this is a case for simple math. 320x200x16 colors updated 30 times per second is already hitting the max bandwidth of the ISA bus.

Using a PPro it would be advisable to also employ a properly speedy graphics card as the cpu supports write combining which may result in dandy speedups in some titles.
The 16bit code issue may be rather inane as old software is either not that demanding or newer (protected mode) titles, at least in DOS, often employ custom code(via a protected mode host) instead of slow(er) 16bit based BIOS procedures. No guarantees though - testing is always recommended.

Also maybe watch this well made comparison of the PPro & PMMX(both clocked at 233mhz)
https://www.youtube.com/watch?v=IzX1aLVRcrQ

kingcake wrote on 2024-06-02, 03:18:

Gmlb256 wrote on 2024-06-01, 15:59:

AlessandroB wrote on 2024-05-31, 19:52:

I can find a nice SBC with Pentium Pro 200 to fit in my amiga 2000, the inly problem is that the only graphic card i can fir will be a ISA card… that make the Pentium Pro inusable in mid DOS gaming??

Not unusable for DOS gaming but the experience isn't ideal because of the bottleneck of an ISA video card (especially with SVGA/VESA video modes) and performance hit that the Pentium Pro has with 16-bit and mixed codes where partial registers usage are common.

This is the correct answer. Ignore all the handwaving, this is a case for simple math. 320x200x16 colors updated 30 times per second is already hitting the max bandwidth of the ISA bus.

It depends. At ~8 MHz, maybe. After the Gang of Nine had standardized things ("ISA bus").

Before this happened, the bus ran at up to 12 MHz, depending on the AT clones:
There had been high-end ATs circa '87/'88 running at high clock speed.

Some ran at 20 MHz, even, though probably with bus/CPU being decoupled by chipset.

Memory boards by Bocca, AST or Quadram had 10 or 12 MHz being mentioned in their manuals.

In the 90s, AT owners had run ISA bus at up to 16 MHz..

At speeds past ~10 MHz, at 0WS, ISA becomes less and less of a pain.

PS: The reason why ISA was defined at 8 MHz was because it oriented itself on the IBM AT and its bus.
And there were just two models of the Model 5170: 6 MHz and 8 MHz.
Whether or not IBM had a technical reason to not release a faster AT after this is another story. 🤷‍♂️

Pentium boards you often find them locked to reference/2, what's that 14.318/2 or something, 7 and a bit, so yeah, ISA can be particularly dire on Pentium up, it's crippled.

BitWrangler wrote on 2024-06-02, 16:51:

Pentium boards you often find them locked to reference/2, what's that 14.318/2 or something, 7 and a bit, so yeah, ISA can be particularly dire on Pentium up, it's crippled.

The ISA bus clock on most motherboards from that era and later are usually generated from the PCI one, PCICLK/4 is often used when the FSB is set to 66 MHz (PCICLK = 66 MHz / 2 = 33 MHz).