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Finally Figured out the Blue Lightning upgrade....

creepingnet

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Feb 25, 2005
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Reno, NV
When I last left off, I had procured a 1991 Compaq DeskPro 386s/20 with a IBM Blue Lightning Upgrade chip of some sort in it, and I think I finally figured out what this chip actually is.

It's the Evergreen upgrade. - https://www.ardent-tool.com/fspencer/8580proc.htm

Basically it came in clock doubled and clock tripled versions, and like another person said on my previous post to this blog, it's the rare 16K cache BLX3 upgrade chip. Turns out this site had the drivers for it too, so I downloaded them (it's something like to486.exe or something like that and requires a 720K floppy - I'll mirror it on my site when I'm done building out the new build of it).

Once those drivers loaded - HOLY CRAP this thing flies. It's almost on par with one of my DX2 or DX4 machines. Kind of shocking it can get that far along on a motherboard designed for a pokey little 20Mhz 386SX. But what does this mean for me? TWO retro machines in one computer - a slower, 286-classish 386SX in one, and a faster 486DX-ish thing in another. Arachne SCREAMS on it, almost somewhat better than on my DX4-100 somehow (and good thing).

Too bad nobody's still making these, and not a lot of them were made. It'd make a lot of 386SX based computers far more useful for what us retrocomputing enthusiasts use them for, and allow some of us to have only one vintage machine that fits the bill of many. It'd also give some value to a 386SX. Maybe this is something I should look into at some point.

The only downside is TopBench, SysChk, SpeedSys, and a lot of other benchmark/sys info utilities puke on themselves, as well as Links for DOS (so no Links browser, will need to do the TLS hack for Arachne instead). So I can't really benchmark much, did manage to look at the performance differences in TopBench though, just can't add the machine to the database. I'm guessing that "piggyback" CPU confuses some utilities.

Still though, being able to hot-swap using DOS multiboot config between two different CPU is quite cool indeed.
 

vwestlife

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May 2, 2008
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Location
central NJ
I have an IBM OEM 486SLC3 upgrade module in my PS/2 Model 56. With a fast SCSI hard drive it performs very well:


Reportedly all 486SLC3's are actually a full-fledged 32-bit Blue Lighting (486BLX3) chip, but crippled to a 16-bit external data bus to use with a 286/386SX-based motherboard.
 

Plasma

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Nov 7, 2005
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A 386SX is still useful for a lot of things, and a speed demon compared to a 5150. It's fun to push old systems as fast as possible, but in the end I removed my CPU upgrades because I felt it changed the personality of the machine. But if you can toggle it then I suppose you have the best of both worlds.
 

creepingnet

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Joined
Feb 25, 2005
Messages
1,097
Location
Reno, NV
The switchability is really the unexpected beauty of this setup. I learned at one point today poking around Vogons there's a command-line switch for the driver that allows it to run in DX2 or DX4 mode - so I can run it at 20MHz (386SX), 40MHz (486BLX2), or 60MHz (486BLX3). If the 40MHz was that fast (feels a lot like my actual NEC Versa 40EC which is a 40MHz 486 DX2 SL which also feels faster than it should be), then 60MHz means I could probably run some pretty hardcore stuff on it (if I upgraded the graphics of course). Arachne was surprisingly tolerable in 386SX mode, and quite fast in 486BLX2 mode, so the /3 switch should provide even more gains surprsingly.
 
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