WTB: Amiga 2000 486 Bridgeboard

[spirantho]

I knew they (386/486) were rare but didn't know they were THAT rare!
Actually I think I've ever seen only one 286 on ebay... mostly 8088 cards.

I have two 486-ish bridgeboards - they're not that rare really. Well, actually, I have three, but one doesn't work, and that is rare, which is really annoying (it's an A2386SX modified to have a 486SLC33 onboard instead of a 80386SX).

If you're going to use a bridgeboard in an A2000, you may need to look at soldering the 16-bit parts of the ISA slots in. It's easy, but time-consuming (I did it on one of mine). If you don't, you'll be limited to an 8-bit soundcard like a Soundblaster II, and an 8-bit anything-else card (ethernet, IDE etc.).

I have an A2386SX which is upgraded with a 486SLC2-50 (8MB RAM onboard), Trident 256K SVGA card, Soundblaster AWE 64 and a no-name IDE/Floppy card, with a small hard disk attached. That's my Amiga in the living room, it's in a standard A2000 KS1.3 with a GVP SCSI card.

In my other room, I have another A2000, this time with OS3.9, an Apollo 2030@50MHz, 32MB RAM, Picasso II, Ariadne card, Catweasel MkII... and also a GoldenGate 486SLC which is powered by a Cyrix 80486SLC @ 25MHz. This has 8MB onboard at the moment. Graphics card is a 1MB Thunderbolt ISA (Cirrus Logic CL5422 I think), Soundblaster II (8-bit), 3-Com 3c509 (8-bit).

The Goldengate is the better integrated of the two, it uses Amiga floppy drives and Amiga partitions much better. In fact mine uses a 4GB SSD off the Catweasel (which has a Buddha built in). It's also better integrated with serial ports, parallel ports, the mouse, etc., and has a Monitor Master automatic switcher.

The reason I've posted all that stuff, isn't to gloat. (well maybe a little ). But if it's of any help I can tell you how certain pieces of software runs on them. The thing to remember is that the 486SLC chips are not true 486-class chips, they're turbo-386s. They have a 16-bit databus, not 32-bit. Also remember the graphics cards are running on an 8MHz (or 10MHz if you want on the GG) ISA bus. Not fast.

As for how rare true 486/586 bridgeboards are - they don't exist. The closest was an SBC released (possibly) by Blittersoft, I think, but they were just SBCs. Much less cool.

[spirantho]

I never outgrew it.

Of course you can buy a cheap PC, but where's the fun in that? There are loads of reasons for using a real PC over an expensive, slow bridgeboard.... but nothing is quite as funky as having your Amiga switch over to a DOS machine for a bit and then back again whenever you want.

Incidentally, there's two slots in the A2000 motherboard which are 16-bit, that's true... but the bridgeboard uses one of them! Hence only one left, which I very strongly recommend you use for as fast an SVGA card as you can get.

I did actually try Alone in the Dark on my bridgeboards. The vanilla 386SX ran it rather slowly, the GG ran it well and the 386SX after upgrading to 50MHz 486SLC ran it very well, a definite improvement.

It's true, for most people, using a bridgeboard is daft... but for people like myself it's still fun to tinker with, so I do. Which, after all, is the reason many of us still use Amigas at all.

[spirantho]

@hardlink

well said.

@crazy lunatic geeks

http://members.iinet.net.au/~davem2/overclock/a2386.html is an interesting webpage. Not tried any of it myself though!

[spirantho]

I'll try and get some bridgeboard MIPS shots later, but in the meantime, this is what my A1 G4@800 can do! All running under OS4.1 (Remember: to run PC-Task you may need to clear your languages in your Locale prefs). The pictures are DOSBox, PC-Task Dynamic and PC-Task Interpretive respectively!

I downloaded MIPS from

http://ftp://ftp.simtel.net/pub/simtelnet/msdos/sysinfo/mips.zip

More benchmarks please! And before anyone says anything, yes, I know MIPS is a completely meaningless benchmark, especially on emulators, but if we're comparing like machines then it may give us some clue!

[spirantho]

Here's some more benchmarks for anyone interested!

These are:
A4000 (CSPPC) OS 4 dynamic
A4000 OS 4 interpretive
A4000 OS 3.9 dynamic
A4000 OS 3.9 interpretive
GoldenGate 486SLC25 (with FAST mode)

[spirantho]

And just for the heck of it:

A KCS PowerPC board in an A500.

The one thing it really proves is that you can't trust benchmarks in an emulator. The benchmarks for the hardware should be reliable, though (or at least as reliable as MIPS ever are!)

[spirantho]

I don't think the overall score is an average or anything like that. On an emulator I think the numbers are pretty meaningless really.

As for the XT being faster than the AT, not sure how you get that. Remember the numbers are how much faster than the baseline your machine is, i.e. 22 against the XT means your machine is 22 times faster than an XT.