Built myself a 486

[wierd_w]

The issue with data bottlenecking was the reason why AGP has the GART.

 

https://en.wikipedia.org/wiki/Graphics_address_remapping_table

 

Regardless of what standards convention you use (DirectX, VESA, et al) to get "hardware agnostic" graphics, despite the bespoke implementations present-- the lack of a pathway to get data into the card, or for the card to signal it is ready for data, etc-- meant that such devices had no choice but to have the CPU involved, and to make use of the main system bus.  This tied up the CPU, which made the simple act of drawing the screen very intensive.  Some tricks could be done with hardware blitters and buffers, but any time the data inside the card needed to be updated, meant the CPU had to be involved, and OOF-- there's that operation penalty.

 

As the wikipedia article points out, AGP introduced a new kind of MMU, which could move and map memory, allowing the card and chipset to work together for the card and its drivers to offload memory operations from the CPU.

 

As video cards have become more and more complex (approaching general purpose computing engines in their own right-- which is why bitcoin mining and super computing applications can leverage them today), this capability has really demonstrated the power of that kind of offloading. 

 

Back in the day, the rate that you could get pixels on the screen, was tied to how fast your CPU could move bits of memory around.  Something like the word size of the CPU, or the speed of the front side bus, was very important--- it was why CPU speed was such a major factor, even with higher end cards.

[eightbit]

9 hours ago, Keatah said:

Love the red VIA-based 1394 card. These were the ones I had the most success with.

 

Nice e-waste pile. So which graphics chip are you keeping in this build?

 

For this build I am definitely sticking with the Stealth64 in those pictures. This is the 2MB DRAM version using the Vision864 chip. Not an easy VLB card to find nowadays and usually commands a high price tag. The guy who sold this lot didn't know much about it at all...just said he used to work on computers for family and friends over 20 years ago and amassed this pile of stuff. 

 

For the next build (since I have everything I need except a case really) I'll use that SiS board that I originally had in here and maybe outfit it with an Overdrive chip and pair it with the Fahrenheit board. That board was actually really good...the second fastest VLB board I own with this Stealth64 being king. 

 

Right now this 486 is completely done...well everything except the BIOS chip you are making for me. Thanks again for that! Once that is in place and confirmed working I'll move the CF data over to a larger CF drive and close her up. Then it's all about exploring the games, demos, etc. 

 

[wierd_w]

One thing to note---  The major difference between a modern ATX case, and an older AT style case, is basically the form card in the back, and the kind of power button.  Most AT boards will mount just fine on an ATX mounting surface. (may need a few plastic stand offs with the tips cut off.)

 

Either a metal sheet with a simple hole cut in it stuffed into the form card hole, (or a 3D printed version there of), and it would be off to the races. Well, aside from the nostalgia factor of having yellowed plastic.  Replacing the button with a 2-throw switch is just a few bucks on amazon away.

 

A suitable set of switches (since the power switch on AT supplies is really just a low voltage ON signal at 5v) can be obtained off Amazon for just a few bucks.

 

(I am actually embarking on an ambitious project to 3D print an entire AT style computer case, since I have a printer large enough for the task... but I find that if I am going to have the printer tied up for a solid month to produce such a thing, I want it to be extra special, and so have been working on trying to produce a neat textured set of doors and such-- which is taking a lot of time)

[eightbit]

Yeah, I know I can get it into an ATX case and I have a case that I can do that, but I kind of an envisioning a true AT case in a desktop form factor for the next build. One of those beefy classic beige cases with a turbo button, LED CPU speed readout, three 5 1/4 drive bays and a 3 1/2 inch sideways bay. Nice big heavy metal case that has no problem supporting my 21 inch Starlogic CRT

[Keatah]

Anyone care to give this guy a hand in fixing his 486? I'm a little stretched for time ATM.

 

[eightbit]

Just when I thought I was done....lol.

 

I have decided to change the sound card in this build. While the SoundBlaster CT2770 I have in here is an excellent card, it suffers from an MPU-401 bug that is quite annoying. If I didn't own a Roland SoundCanvas I would never have known about it, but I do so it is annoying.

 

What happens is if you launch any game using a SoundCanvas and general midi (I have the joystick breakout cable to get the MPU-401 interface to the SC) the music will not play and the game will run like it is on an 8086. What I found to correct this problem is a "fix" file from Creative that I have to have loading with the computer (MPU-401 fix) each time. This fixes the problem 99% of the time. But, every once in a while it happens again even with the fix loaded into memory. And, of course, the stupid fix takes up some memory.

 

I tested the sound card I received from the seller that sold me that pile of e-waste the other day and it is based on a Crystal chip. It works great with no such MPU-401 issue at all, but the SB16 DOS compatibility is not the best. Some games sound great, but some others like Tyrian sound like crap.

 

So, I have decided to order the old tried and true card of my youth that I know has superb SB compatibility and no MPU bug, an ESS Audiodrive ES1868F card. So common, pretty darn cheap, but I know these work right and sound great. I probably should have just done that from the start, but I wanted a "soundblaster" in here and never expected to run into issues. Again, if not for the Roland SC I would be just fine. But I need that to work perfectly...I am addicted to the general midi now. I can't live without it!

Edited March 27, 2022 by eightbit

[wierd_w]

As others have pointed out, you can convince a raspberry pi to emulate an mt32.

 

The emulator in question is MUNT.  (I have it compiled and running on my laptop as a softsynth, with dosbox's mpu401 aimed at it. It does more or less faithful mt32 emulation. Soundcanvas Is pretty good, but the MT32/LAPC1 is better still, and widely supported.)

 

With a USB midi cable, MUNT can respond to real midi messages just like a real MT32.

[eightbit]

8 minutes ago, wierd_w said:

As others have pointed out, you can convince a raspberry pi to emulate an mt32.

 

The emulator in question is MUNT.  (I have it compiled and running on my laptop as a softsynth, with dosbox's mpu401 aimed at it. It does more or less faithful mt32 emulation. Soundcanvas Is pretty good, but the MT32/LAPC1 is better still, and widely supported.)

 

With a USB midi cable, MUNT can respond to real midi messages just like a real MT32.

 

I know all about it. But hell no!

 

The Roland SoundCanvas is just too beautiful to emulate. I love this thing. Lots of buttons to push, an orange screen that is music to my eyes, and a really sweet looking motherboard if you take a look inside

 

It's general midi mind you, so not MT32. But when I do go the MT32 route I will be certain to buy a real Roland MT32. I love this real vintage audio hardware almost as much as I love real vintage PC hardware. I got mine for sixty bucks and it has been the best sixty bucks I have spent on anything in years. The Pi thing just does not compare aesthetically at all.

 

 

 

  

Edited March 27, 2022 by eightbit

[wierd_w]

Genuine article MT32 is very $$.

 

I agree that it is also pretty, if you have the space.

 

 

[eightbit]

4 minutes ago, wierd_w said:

Genuine article MT32 is very $$.

 

I agree that it is also pretty, if you have the space.

 

 

 

The SoundCanvas is actually really small. I was surprised at its size when I received it. Its excellent that it mixes normal RCA style audio jacks. So a simple 3.5mm headphone jack to l/r audio cable goes out of the PC and into the SC, and audio l/r out of the SC goes right into my receiver. Super simple and easy solution and general midi in games sounds astounding. Many people have been over to hear the games on this 486 and they are really blown away as I am. 

 

As for the MT32...only a few games really even support it. It was midi before general midi became "general". I know some die hards get an MT32 and a SC and link them together to have it all, but ehh...I don't know. I think for the few games that are MT32 only on the PC I will probably just "deal" with normal sound. Now, for games that support general midi....thousands. 

 

I personally think someone looking to enjoy all midi has to offer in games should just buy an SC-55 or SC-50 (what I have) and call it a day. It's really more than I will ever need to be honest. 

 

If I find a cheap MT32 however I will probably pick it up. But its going to have to be cheap

 

 

 

 

Edited March 27, 2022 by eightbit

[eightbit]

I'd like to once again publicly thank Keetah for helping me with getting an updated BIOS chip burned. I received it today and this excellent 486 build is now even better!

 

Previously the CPU was being detected as a P24T-S CPU at 100MHz, and while that worked fine now the updated BIOS correctly reports it as the DX-4 100MHz CPU that it is. 

 

That is not the reason for the update requirement however. It was because the old BIOS did not have LBA mode so I could not use anything larger than 511MB hard drives. While that was OK since I have a handful of 512MB CF cards, I really wanted to use a native 1GB or better card without the need for HDD overlay software. Now with the update, it detects my 1GB CF cards properly and they can be configured as such properly in DOS fdisk. 

 

There are some other features the new BIOS brings in that I saw just glazing over it as well such as some auto configuring of the L1 and L2 cache (auto detects write back or write through modes, etc) which is really nice.

 

Keetah even labeled the chip professionally for me. You are the MAN. Thank you!

 

 

[Keatah]

Enjoy the new BIOS and the features it brings. Seems you’re satisfied so I’ll send the backup one out shortly.

[eightbit]

1 minute ago, Keatah said:

Enjoy the new BIOS and the features it brings. Seems you’re satisfied so I’ll send the backup one out shortly.

 

Thank you! Yep, one additional feature this brings to the table I forgot to mention is support for AM5x86 CPU's....so maybe one day

[eightbit]

I picked this up today and it is on its way. The seller could not provide any information. Anybody want to guess what chip is under that DCS sticker? I am guessing an ESS of sorts. 

 

The few things that struck me was that it has a real Yamaha OPL chip and it has IDE. I need the IDE as I plan on moving the CD-ROM drive off of this I/O controller. Why? Well, it does not work properly in Windows 3.1 with 32-bit access enabled. If enabled, it blue screens. I have to disable 32-bit access in order to use the CD-ROM drive and while that works I just don't like that. I did a lot of research on this issue and it is documented in many FAQ's from manufacturers online from the era. Either disable 32-bit access OR use an IDE add-in CD-ROM card of sorts.

 

So, if this is actually an ESS Audiodrive I think this is the card for this machine as it ticks all of the boxes for me. If it's something else...well I'm going to give it a go nonetheless so we shall see

 

[wierd_w]

Hard to tell...

 

Looks similar to an Acer 613L.

 

Initial internet scraping suggests 'based on ALS100'. 

 

Peel the sticker?

 

[eightbit]

10 minutes ago, wierd_w said:

 

Peel the sticker?

 

 

First thing I am going to do when it arrives  

 

It could be an ALS chip. I just can't find an example of one of those cards that is married with an actual Yamaha OPL. For a generic card this does not look like it contains cheap components either. Well, guess it will be a pleasant (or unpleasant) surprise. It was only twenty bucks shipped so I don't think I'll loose much sleep over it if it is not my "dream card"....lol.

 

If it is an ALS100, it doesn't sound bad at all:

 

 

 

Edited March 31, 2022 by eightbit

[Keatah]

It's going to have an ALS100. Minus the Q-Expander sound effects, think spatializer, something to make the sound more spacious than it is. Think pre-pre-EAX, or those stereo/ambiance enhancer buttons on some boomboxes. You can do without that, because, it makes the sound sound different than what the developers (of a game) intended. At least I never got a hard-on over stuff like so.

 

 

[eightbit]

Just now, Keatah said:

It's going to have an ALS100. Minus the Q-Expander sound effects, think spatializer, something to make the sound more spacious than it is. Think pre-pre-EAX, or those stereo/ambiance enhancer buttons on some boomboxes. You can do without that, because, it makes the sound sound different than what the developers (of a game) intended. At least I never got a hard-on over stuff like so.

 

 

 

 

I am really not very familiar with the ALS100. I know ESS, Soundblaster (of course), Crystal and some others...but no experience with this.

 

Seems you know much more than I do in this regard. Do you know how it handles regular DOS SB16 support? If you have used one at some point in time do you remember anything not working as expected?

 

As long as the SB16 compatibility is decent I'll probably just stick with it. Right now with a real SB16 I am just not impressed. I guess I was back when I was a kid because it seemed to sound great (especially over no sound which I did for a very long time) but in todays age I am finding 90's Soundblaster cards just exhibit too much noise/interference for my tastes. But beyond that the biggest issue I have is the stupid MPU-401 bug that requires me to launch Creative's "fix" on each boot just to enjoy MIDI via the SoundCanvas without a lockup.

 

 

[wierd_w]

It does have DOS drivers;  is not PnP, uses an eprom to configure, if I am reading right.

 

I will look in earnest when unambiguous ID is made.

[Keatah]

I don't know anything else other than the name Avance Logic, which was bought out by RealTek.

 

I mean I don't have direct experience with it. I do know that some of the ALS chips are PNP, or not PNP. Presence or absence of jumpers isn't a reliable indicator here because the chip can store settings in its internal Flash Memory set by a config program.

Anecdotally I haven't heard of issues with SB compatibility. But then again I was always laser-focused on the standard SoundBlaster 16 (CT1740), because I growed-up with it. Coming from the Apple II and other rigs of the 80's SB16 was a level of sophistication previously unheard of! Forgive the bias here..

 

So.. Let's get the exact chip number and go from there. You may be able to glean some of the features (of a particular chip number) from here. https://www.dosdays.co.uk/topics/Manufacturers/avancelogic.php

[Keatah]

A lot of folks liked to complain about the hiss and noise of SoundBlasters, but, you know, the PC is a noisy environment with all those various Megahertzes flying around at different speeds.

 

So I never considered DAC quality back then. I was more interested in compatibility and just that my games had the right sound effects. The right hardware to be hassle-free and just work. I figure if I'm going to go for quality sound with good SNR and no interference I'm just going to get something with SPDIF/digital outputs and feed that into an outboard amp.

 

Getting a CL WaveBlaster II daughtercard was like advancing to the next level. Couldn't afford SoundCanvas "anything" back then. And by the time I could, soundcards advanced themselves into oblivion with only DACs on a motherboard and "cards" absorbed into the CPU via a stack of APIs.

[eightbit]

8 hours ago, Keatah said:

A lot of folks liked to complain about the hiss and noise of SoundBlasters, but, you know, the PC is a noisy environment with all those various Megahertzes flying around at different speeds.

 

 

I totally here you and back in the day I had no complaints. I also didn't have any complaints about the mini popcorn machine that was my Connor hard drive

 

But, now with this build in this day and age I am also finding ways to improve the experience beyond what it was back then. I am nostalgic for a lot of things, but some not so much. Hence the Gotek, CF to IDE adapter and now the quest for better cleaner sound.

 

The Crystal ISA sound card I received in that batch of e-waste stuff would have fit the bill if only the SB16 compatibility were better. I mean, all the games I had tested had "sound" when choosing SB16 as the option....but what sound you got was really a mixed bag. Some things sounded incredible, some others were just borked. But I will say the sound was super clean. No hiss at all.

 

Honestly though I probably would have dealt with the hiss on the SB16's I have if not for the fact that the DSP is plagued with that MPU-401 bug. It will be a relief not to have that happen anymore on an alternate sound card. Funny thing is that I only know about the bug at all because I am using a Roland SC

[Keatah]

Always wrestled with the cutoff line, when to stop upgrading or improving a machine. When does an upgrade become a tipping point, making the machine too different from its original self.

 

I've kept my 486 stock, not upgrading beyond what was available back then. Today I use Zip disks to transfer software. One parallel-port model on the 486, one USB model on i9/Win11 machine. But I don't transfer much except the occasional game or stuff from word processors. Still love using MS Word 2.0a on Windows 3.1. Like fine motoring on a Sunday drive.

 

I figure if I'm going to go after maximum performance on any vintage game I'm going to use DosBox to pre-test it at various speeds. Oftentimes I just go with that to get my fix to see how it runs at xx MHz.

[zzip]

20 minutes ago, Keatah said:

Always wrestled with the cutoff line, when to stop upgrading or improving a machine. When does an upgrade become a tipping point, making the machine too different from its original self.

I just continuously upgrade parts every few years.   Eventually every part gets replaced and I was able to put together a complete 486 and K6-2 system with the leftovers.

[mr_me]

I upgraded my original computer from 1989 through to about 2008.  Went through three motherboards, until the new ones no longer fit the old AT case. At that point it was just cheaper to get a used name brand PC.