Just got this weird little machine... \ VOGONS

Just got this weird little machine...

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First post, by jbh1977

Posted on 2018-07-09, 12:23

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I've just scored this little 486 machine, a DEC 450D2LP, model PC744-BB. Can anyone tell me a bit more about this? I can find very little information online.

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I've had to replace the floppy and optical drives, as they were no longer working. Apart from that it's been really well looked after, and even looks like it had a new CMOS battery installed recently. Up until a couple of weeks ago it was still being used for industrial control.

According to Norton Diagnostics, the CPU is a 486 DX-50, but according to the BIOS it's a DX2, running at 25MHz, which as far as I understand it can't be right. If it is a DX-50, then shouldn't the FSB be running at 50MHz? Where does the 25MHz come from? Wouldn't that make it a DX2-50? Because that doesn't exist does it? Am very confused.

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Speaking of the CPU, it seems to be on some sort of daughter-board, and there's even room for a second CPU by the look of it. I've never seen this sort of set up before. If anyone knows where I can find info on this board or how to configure it, that would be really useful.

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Graphics are provided by an onboard S3 chipset. Windows 95 thinks it's an S3 911/924, but I'm not so sure. I couldn't get it to display in anything other than 640x480x16 even with the 911/924 drivers.

Audio is provided by an old SB16 (CT2950) I had lying around, and still works great.

Anyone know anything about this machine? Was this a good find? How do I know I'm getting best performance out of it? I haven't run any proper benchmarks on it yet, but DOOM seems a bit more sluggish than I would like.

Thanks.

Reply 1 of 11, by PcBytes

Posted on 2018-07-09, 12:28

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A quick google search says it uses a S3 805, so you might want to try that.

"Enter at your own peril, past the bolted door..."
Main PC: i5 3470, GB B75M-D3H, 16GB RAM, 2x1TB
98SE : P3 650, Soyo SY-6BA+IV, 384MB RAM, 80GB

Reply 2 of 11, by Phreeze

Posted on 2018-07-09, 12:35

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dx2/50 exists 😉 i still have our old one at home

ArGUS Parts list: http://bit.ly/2Ddf89V

Reply 3 of 11, by LeFlash

Posted on 2018-07-09, 12:42

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The other socket is most likely for a 487SX Coprocessor. Useless with your DX-setup.

Fun fact: The 487 included a complete 486. Just an extra pin checked and disabled the 486 in the main socket.
Using the 487 alone did not help as it checks the presence of the main cpu.

Reply 4 of 11, by jbh1977

Posted on 2018-07-09, 12:43

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PcBytes wrote:
A quick google search says it uses a S3 805, so you might want to try that.

That's great. Thanks for the help. I will definitely give that a try. What did you search for though? All I seem to find is random auctions.

Reply 5 of 11, by jbh1977

Posted on 2018-07-09, 12:45

jbh1977 Offline

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Phreeze wrote:
dx2/50 exists 😉 i still have our old one at home

So it sounds like it's a DX2-50, running on a 25MHz FSB. That would certainly explain the sluggish DOOM performance. Thanks for the heads up!

Reply 6 of 11, by PcBytes

Posted on 2018-07-09, 13:01

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jbh1977 wrote:
PcBytes wrote:
A quick google search says it uses a S3 805, so you might want to try that.

That's great. Thanks for the help. I will definitely give that a try. What did you search for though? All I seem to find is random auctions.

Simply the name of the machine (DEC 450D2LP) then S3 😀

http://www.verycomputer.com/7_b5857b9dc2950f8b_1.htm

"Enter at your own peril, past the bolted door..."
Main PC: i5 3470, GB B75M-D3H, 16GB RAM, 2x1TB
98SE : P3 650, Soyo SY-6BA+IV, 384MB RAM, 80GB

Reply 7 of 11, by DeafPK

Posted on 2018-07-10, 06:40

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My DEC 486sx LP

Mine has a 924 graphics card. It also requires parity ram, i. e. 36-bit instead of regular 32-bit.

"an occasional fart in their general direction would provide more than enough cooling" —PCBONEZ

Reply 8 of 11, by mcobit

Posted on 2018-07-10, 19:27

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I think I have the same or very similar machine. It has problems with the onboard graphics though. Sometimes it works notmally and sometimes it produces a garbeled image. Need to desonder some vram chips I guess but didn' find the time recently. I would use an isa card but that would not have the speedadvantage of the onboard graphics that are vlb.

Mine has a DX2 66 MHz CPU.

Reply 9 of 11, by jbh1977

Posted on 2018-07-11, 08:29

jbh1977 Offline

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mcobit wrote:
I think I have the same or very similar machine. It has problems with the onboard graphics though. Sometimes it works notmally and sometimes it produces a garbeled image. Need to desonder some vram chips I guess but didn' find the time recently. I would use an isa card but that would not have the speedadvantage of the onboard graphics that are vlb.

So far I've not been able to get Windows to run in anything other than the default VGA mode, but it runs all my DOS games just fine, so I'm happy for now.

Have just done a fresh install of Windows 95, so I will try various drivers and see how that goes... 😊

Reply 10 of 11, by The Serpent Rider

Posted on 2018-07-11, 10:02

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and there's even room for a second CPU by the look of it

That's a socket for Overdrive ODP with one extra leg to disable your current CPU. I think this board will ignore anything else in this socket even if you remove current CPU.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 11 of 11, by chinny22

Posted on 2018-07-12, 23:45

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DEC's were always well built PC's.
And I love the LPX "Pizza box" form factor, even though its non-standard.
Simpy searching 450D2LP brings up a few results.
Here is a good one listing video card (S3 805 VLB) as well as other interesting specs
http://www.verycomputer.com/7_b5857b9dc2950f8b_1.htm

Here is the service manual, useful for CPU jumper settings
http://www.google.co.uk/url?sa=t&rct=j&q=&esr … 2EkRV-wqzk6Q_JA

it also seems to confirm that its 50Mhz as the 433D2LP is 33Mhz

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