My Unfortunate 486 Build

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My Unfortunate 486 Build

Postby flakes » 2019-7-11 @ 01:36

Hi

So I decided I wanted a 486 like I had as a teenager. My requirements were for a simple setup 486DX2 ~66MHz 4-8MB ram, SB16, 1GB HDD and Network. I thought it would be easy to find the parts as who would want them these days! This led me to look on the net and find this site amongst other information.
So I started searching for parts. Gumtree and Facebook ads and weeks of people offering me P4 items even though I asked for old items and am not interested in P4 or newer.
I managed to assemble the following parts:
• Intel DX2ODPR66 (486 DX2 66 Overdrive)
• Creative SB16 value
• Trident TVGA 8900B 512KB
• Crappy ACER Motherboard (Stuffed)
• SCSI Card

A Month later I managed to find the following:
• Octek “Hawk” 486 Motherboard (More about this later )
• Fitted in socket 486DX 33
• RAM! More on this as well
• Goldstar Prime 2 Controller
So all items sitting on the bench looking Promising…. Cant wait to start the build.

I Hit Ebay and grabbed a few items after reading a few of the forums here. I ordered a ATX to AT power cable, IDE to SD adapter, BIOS POST ID, USB Floppy, Gotek Floppy.
All parts arrived after a while of waiting on China EBay sellers and good old Aust. Post.

Excitement for build couldn’t hold me back. I assembled the Motherboard and VGA with the new power adapter on the bench to start testing. Signs were very positive, Motherboard Flashed up and a Display was shown on my test LCD.

So I started doing a check out of the “System”. I noted that the Memory total was showing only 256KB. This was alarming as I thought (and had been told by the bloke I bought it off) that there was 8 x 1MB sims installed. I had never actually checked. Turns out that there was 4 x 1MB sims and a mix of something else that the motherboard wouldn’t detect with it installed. I am yet to work out what the sims are but I am happy with 4MB at the moment. It shows the correct Value of the 4 x 1MB sims.

With it successfully posting I decided to change the CPU to my Overdrive DX2 66. This posted and seemed to be working well. I hooked up a Floppy drive and was able to boot into Windows98 Dos boot Disk. All good, Ripper I have a 486 that I was after….. OR NOT!

I then powered it all down and put in My Sound Blaster, Network and SD to IDE. It all booted up nice. There was noise from the SB in the speakers, (Have to look into that!) and all seemed to be working (No Smoke signals).

Time to run some Diagnostics and see what is actually working. I ran NSSI and was looking at the benchmarks, it was running just slower that the 486DX2 66 that it was comparing it against. The FPU was about 10% off what it should have been. I then ran DR Hard to see further in depth what I had. I noticed it said that there was a statement about No cache! WFT!
Back to Vogons…. “486 Cache” oh Crap, I remember now, the issues with fake cache on cheap Motherboards. Surely I can’t still be finding motherboards with it. They must all be dead by now!
So out came cachechk. Sure enough “There appears to be no cache on the Motherboard” error (Something Like that). S#!t.

I have installed DOS 6.22 and Win 3.11 and it seems to run. I am not sure if it’s because I know its missing the cache making me think it’s slow and crap or just what I should expect!

So I am thinking do I go ahead with the build or scrap it and look for another board.
motherboard.jpg
Motherboard

VGA.jpg
VGA

IO.jpg
I/O Prime 2c

Net.jpg
Network

SB.jpg
SB
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Re: My Unfortunate 486 Build

Postby treeman » 2019-7-11 @ 03:10

soldered on cache chips... usually a good indicator of fake cache, can't make it out bios is socketed or soldered?

not all is lost if u have fake cache it can be desoldered and new sockets installed and replaced with real cache.

In alot of the cases the bios will pick up the real cache, hopefully somebody that knows this board well will pop up.

You sound like your from Australia?
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Re: My Unfortunate 486 Build

Postby flakes » 2019-7-11 @ 04:25

Hi

Yep from Southern Adelaide.

The BIOS is socketed. I made a dump of the BIOS and its in the 486 BIOS Part of the Forums. I cant trace (or havent been bothered to) trace the lines from the cache modules. Suspect they will go around in circles like many before.

Might put some time in to it as 486 boards arent that common anymore.
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Re: My Unfortunate 486 Build

Postby treeman » 2019-7-11 @ 04:43

usually what happens with fake cache is that the traces and functionality is there but the Chinese manufacturers skimmed and saved a few cents/dollars on the parts, no socket and a fake plastic mould with fake printing.

look up the part numbers from the cache on google it should shed some light, as I recall if it has printed WB write back on the cache chips its a definite sign they are fake.

If you have the tools it is not that expensive to pick up sockets, cache + tag chips from ebay (non genuine Chinese chips but they do work)

Think what you need to research is has anybody with the same board/bios managed it to recognise real cache. As I understand the bios should be written for the particular Chipset your board uses so could try a bios from a different board but same chipset too (I have done this before)
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Re: My Unfortunate 486 Build

Postby flakes » 2019-7-11 @ 05:17

hmm... Plot thickens...

What would be the cache chips?
all i can identify are the 74 series Hex inverters, buffers, NANDs, Octal Buffer & Line drivers, Like listed below...

OPTi F82C206L - Integrated Peripheral Controller
OPTi 82C496 - DXBB PC/AT Chipset

74SLS04N - HEX inverter
MC74F00N - QUAD 2-INPUT NAND GATE FAST SCHOTTKY TTL
MC74F244N - OCTAL BUFFER/LINE DRIVER
74FCT244 - CMOS OCTAL. BUFFER/LINE DRIVER
MC74F74N - dual D-type flip-flop
MC74F245N
MC74F244N
and the list of 74 series goes on...
there is only 3 chips i cant make out with my current Photos.

SO... my theory is that it never had Cache in its design? Or am I completly Wrong (Happy to be told ether way)
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Re: My Unfortunate 486 Build

Postby treeman » 2019-7-11 @ 05:23

think you may be right there, I didn't look that carefully at the chips on the board in the picture.

stason shows it as no cache, is there a selection for external cache in the bios?
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Re: My Unfortunate 486 Build

Postby canthearu » 2019-7-11 @ 06:13

I don't think the OPs board had cache to begin with.

Given it's design, I would say just put the DX33 back in and use it as a fast 386 class computer.

Save the DX66 for a computer with VLB and real cache.
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Re: My Unfortunate 486 Build

Postby flakes » 2019-7-11 @ 08:43

Hi.

Yep thats what its looking like. Pitty i paid for the board. not too much but enough to make me annoyed a bit. Might put it up for sale as i have a 286 and 386 on the way.

ANyone selling a VLB or PCI with real Cche :-)
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Re: My Unfortunate 486 Build

Postby treeman » 2019-7-11 @ 08:56

the only cost effective thing u could do to try get it that 10 or 15 more percent would be putting in a 80mhz crystal which is halved to get a 40mhz fsb, current is a 66mhz crystal which runs at half so 33fsb.

That overdrive cpu *should* run at 80mhz then which in theory might be compare to a dx2 66 with cache? (I am not sure) but I have personally clocked a overdrive 66 to 80mhz and in duke nukem 3d vga mode the difference was quiet noticeable.

I am only suggesting this because you said you wanted a dx2 66 pc like from your teenage years.
The crystal is about 5-10 bux so it is not a big investment.

However it all depends in your application.

I have a 386 dx40 586 160 (really a over clocked 486 on a pci board) and a pentium 1 166

early dos, mid dos and late dos games. probably no point having. a 386dx and a 486dx2
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Re: My Unfortunate 486 Build

Postby canthearu » 2019-7-11 @ 10:33

Only problem with overclocking the CPU is that it still does nothing for VGA performance. If you are wanting to play doom or quake, then ISA is still quite a bottleneck.

Only problem is I probably have too many PCs lol

286 12mhz - OAK OKI067 VGA ISA - SB 2.0
386-DX 40mhz - ET4000 ISA - SB16 OPL3
486-DX2 66mhz - S3 806 VLB - SB16 CQM
5x86-DX5-133mhz - S3 864 PCI - Yamaha YMF-719 with Dreamblaster S1 wavetable
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Re: My Unfortunate 486 Build

Postby SirNickity » 2019-7-11 @ 18:23

Yeah, this is a very low-end 486 board. Dead giveaways -- ISA only, no ZIF socket. If you're getting a proper 386, just pass it on, as you don't need a 386, a lame 486, and a fast 486. (Unless you just want the hardware, then by all means.)
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Re: My Unfortunate 486 Build

Postby flakes » 2019-7-12 @ 06:04

I will see if anything turns up tonight at the retro Computer group here in adelaide... Might shelve it for a while.
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Re: My Unfortunate 486 Build

Postby derSammler » 2019-7-12 @ 07:55

canthearu wrote:Only problem with overclocking the CPU is that it still does nothing for VGA performance. If you are wanting to play doom or quake, then ISA is still quite a bottleneck.

DOOM can run quite nicely with an ISA graphics card, as long as you use a good one (a Trident is the opposite and better suitable for a 286/386sx). Quake on a 486 makes no sense anyway; it will never be really playable due to the lacking FPU performance.
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Re: My Unfortunate 486 Build

Postby canthearu » 2019-7-12 @ 08:59

I'll chuck an ET4000 ISA into my 486 DX2-66 later tonight and let you know how doom goes

You are right about quake, it just doesn't make sense on a 486, I certainly make a bad reference there. More looking at games like Heretic, maybe Descent and duke 3d.
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Re: My Unfortunate 486 Build

Postby flakes » 2019-7-12 @ 13:23

Interested to know how you go. I picked up another board tonight that has 256KB cache so will give it a go. I definitely need to find a VGA that is better spec than the one i have.
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Re: My Unfortunate 486 Build

Postby retardware » 2019-7-12 @ 13:47

SirNickity wrote:... low-end 486 board. Dead giveaways -- ISA only, no ZIF socket.

Umm... I disagree.
There exist quite some excellent 486 boards with ISA only and no ZIF socket that were produced, before VLB and ZIF sockets were introduced at all.
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Re: My Unfortunate 486 Build

Postby derSammler » 2019-7-12 @ 14:01

He was refering to that particular board - and he's correct. It is a very low-end board. Made by OCTEK, OPTi chipset, no L2 cache option. ZIF socket and VLB were no issues in 1991, since neither existed back then, but leaving out L2 cache is almost a definition of "low-end".
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Re: My Unfortunate 486 Build

Postby treeman » 2019-7-12 @ 14:58

I have a similar octek hippo vl+ board that doesn't have cache but uses dca (dynamic cache architecture) where the cache runs direct from the ram chips, but that requires edram, unfortunately for op his is not dca or doesn't have cache, which puts it at a low end of octek products
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Re: My Unfortunate 486 Build

Postby SirNickity » 2019-7-12 @ 18:30

I might have been taking some liberty with the phrase "low end". I didn't mean "poor quality" exactly, but rather it is either from early in the 486 lineage, or later in the 486 lineage but built to the bare minimum. Low end. The lack of cache is definitely a factor there as well.

Either way, if your goal is a DX2/66, this is probably not the board for you. If you're going to build a 386, this board is probably not better enough to warrant having both -- at least not out of necessity. That's the main takeaway I was trying to express.

IMO -- and it's just opinion -- these boards don't make much sense today. It's not 1993. Back then, you might have bought this motherboard because you just need a computer and a higher-end board costs more, and so does all the new VLB stuff, but it's getting hard to justify buying older 386 parts anymore. At least with a "value" board, you can re-use your (or second-hand) ISA parts for now, and maybe move up to a VLB board next year while recouping your investment in the CPU, RAM, case, software, monitor, etc.. Now, if you're building a 486, it isn't because you need something on which to do your homework. You can target what you want, without having to "make do" just so you can have a daily driver in the meantime.
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Re: My Unfortunate 486 Build

Postby flakes » 2019-7-12 @ 22:31

VLB and PCI are a nice feature of the end of line 486's. I never had that type of setup as a teenager. It was all ISA. I have a P233 that is PCI and gives me the speed i need for the games i want to run on it. I want an early 90's (before 93) build that was typical of the mid range out there with maby a good video card (Subject to opinion).

VLB is nice but just try to find any of them now... At the moment i'm not prepared to spend mega $ on a VLB board that to be honest doesn't really represent what 90% of people were gaming on in 1991.

I know it's "he with the best toy wins"

Just to find a decent s3 or similar iSA video like i had back then.
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