Re: CpuSpd - A Hardware Based CPU Speed Control Utility for DOS/Win9X Retro Gaming

Posted on 2024-05-14, 18:59

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Has anyone got any examples of cpuspd and the available slowdown settings on say a MMX CPU from anywhere in the region of 166 to 233? Current setup is a Cyrix 5x86-120, and with the ability to drop the multiplier to 1x and disable L1 cache, it is broadly equivalent to a 386dx-40. Can cpuspd drop an …

---

Re: what was it like watching the death of 3dfx post voodoo 3 (late 1999-2000)?

Posted on 2024-05-13, 19:47

by

by megatron-uk

in Milliways

in Milliways

I actually think 3dfx were doomed from the outset. Their architecture gave them a massive boost early on and an easy way to scale performance.... to a point . But to make any radical changes and add features to more fully support what were becoming the defacto 3d gaming APIs (OpenGL and direct3d) …

---

Re: [SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-13, 06:54

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

IOCHRDY means "Input Output Channel Ready" and can be used a short cut to make PIO transfers efficient. The hard drive issues IOCHRDY when it's ready to send or receive data. If the BIOS knows about this, it doesn't have to poll quite as much. Shows up more with VLB controllers. It's on PIN 27, yes …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-13, 06:46

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

I'm wondering if the issue is actually something related to the VIA chipset DMA implementation. Yes sounds like something is messing with it - are there any interesting options in the BIOS to fiddle with around the ISA bus? I can also recommend the Crystal based ISA cards - some of them are super …

---

Re: [SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-12, 22:09

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've just encountered this signal/bus setting on my socket 3 single board computer setup. I was having major digital audio playback issues - popping, clicking etc, regardless of ISA card used, and changing this IOCHREADY option the bios from a default of "disabled" to "enabled" has resolved all …

---

Re: Is the Pentium 4 underrated for retro computing?

Posted on 2024-05-12, 16:36

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I don't disagree - if you have a need for the fastest possible system with fully working ISA, then the P4 is your best option. I have one myself (ibase mb800) purely for hosting an ancient Transputer interface card in a (relatively) modern system with a current version of Linux. It worked well for …

---

Re: Is the Pentium 4 underrated for retro computing?

Posted on 2024-05-11, 22:54

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There's quite a difference to getting things working under Windows with its audio compatibility layers and natively in DOS. Even with a real ISA soundcard in real DOS you will never get 100% compatibility. Of the 290 titles I have tested on my most recent system I probably have somewhere in the …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-11, 15:17

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

Weird that the BIOS allowed or even defaulted such an important ISA signal to be turned off, haven't seen that before... 🤔 The only thing I can think of is that it is something specific to being an industrial SBC board, and not a general purposes design. Perhaps it's there to guarantee the bus …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-11, 14:18

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

So I think I have finally gotten to the bottom of the digital audio crackle / popping issues. Whilst playing around with BIOS options to tweak the recently installed Cyrix cpu, I went hunting to see if there was anything related to DMA settings, latency, timers etc. There wasn't anything, but there …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-11, 10:35

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

For an all-in-one, exclusively Dos system, I think this makes the Cyrix chip a more flexible option than the AMD.

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-11, 10:12

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

Reran selected benchmarks with the Cyrix 586-120 set to various slowdown states: cyrix-slowdown.png With purely software settings via SETMUL, I can get approximately the following speeds: - Native - 486DX2-66 (multiplier set to 1x) - 386DX-40 / 486DLC-40 (multiplier set to 1x, L1 cache disabled) …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-10, 19:59

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

No I didn't. The Cyrix was an opportunity to increase speeds a little, but the primary goal was to have something that was more configurable than the AMD. I suspect that at 160MHz it would be ahead of the 120mhz Cyrix again a little in certain tests, if the Ultimate 486 benchmark thread is anything …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-10, 16:34

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

Comparison of AMD X5 133MHz vs Cyrix 5x86 100 (3x33) and 120 (3x40) performance on the Tiny 486 SBC system: amd-vs-cyrix.png The Cyrix at 100MHz is getting more than 90% of the performance of the AMD, yet at only 75% of the frequency. Increasing the bus up to 40MHz makes a substantial difference, …

---

Re: DOS software for post-ISA sound devices

Posted on 2024-05-10, 15:12

by

by megatron-uk

in Marvin \ Sound

in Marvin \ Sound

There's the JUDAS audio / mixing / tracker playback library, which has support for SB, GUS and Intel ICH AC97 audio codecs: https://github.com/volkertb/JUDAS

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-10, 13:36

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

The Cyrix 5x86-100 also arrived. I'm currently running it through the same benchmarks as the Am5x86-133. So far with the same system settings it seems to have far better memory speeds (L1 + L2 cache) and the benchmarks show that for 75% of the clock speed of the AMD chip, you get approximately 90% …

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-10, 13:31

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

The alternative Yamaha card (actually a YMF-718, not a YMF-715 which I thought I ordered) arrived today. No difference in compatibility (good!) or digital audio playback (crackling/bad!). I'm wondering if the issue is actually something related to the VIA chipset DMA implementation. Now I need to …

---

Re: The King has left the Building.

Posted on 2024-05-10, 07:58

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

"No other CPU made such a difference" Really????? The z80, 6502 and m68000 would like to have a chat with you.

---

Re: Trying to build a retro DOS/Win98 computer.

Posted on 2024-05-09, 22:14

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

That board still has no ISA slots so if you are intending on doing real dos gaming, rather than emulation or dos-in-windows it really isn't ideal.

---

Re: Tiny 486 build - SBC with ISA backplane

Posted on 2024-05-09, 15:17

by

by megatron-uk

in Marvin \ System Specs

in Marvin \ System Specs

Replacement Yamaha card hasn't arrived yet, but I have now ordered a Cyrix 5x86-100 to test in place of the Am5x86-133. I intend to test it at 3x33 and then at a 3x40 overclock and see if it will give me both a slight speed increase for some of those later 3d titles, as well as allow a bit more …

---

Re: Is the Pentium 4 underrated for retro computing?

Posted on 2024-05-09, 11:26

by

by megatron-uk

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The P4 was trash when it was introduced and it's still trash now. There were better options when it came out, and there are still better options now. Honestly, if you want an Intel, stick to the really solid P3 or go right on to the Core series. Skip the P4 entirely. AMD had a solid range of options …

---