VOGONS


First post, by BlackLinus24

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Hi,

I'm fairly new to PICMG Blackplanes but when I came across a i386 SBC (photo attached) I was curious whether I could build a i386 PC using a passive PICMG backplane with some other ISA expansion cards, like I/O controller, VGA and soundcard.

I'm still waiting to get all the pieces delivered. So far I've only received the backplane. I would be interested to hear if anybody here has had the same idea or has been tinkering around with these components as well. Is it me being foolish or would this actually work?

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Reply 1 of 18, by cyclone3d

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Should work just fine. I have a regular ISA only backplane for my 386 SBC, but it shouldn't matter if you use a PICMG backplane at all.

Yamaha YMF modified setupds and drivers
Yamaha XG resource repository - updated November 27, 2018
Yamaha YMF7x4 Guide
AW744L II - YMF744 - AOpen Cobra Sound Card - Install SB-Link Header

Reply 2 of 18, by chrismeyer6

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From a cursory glance it looks like with the Isa only 386 SBC just the Isa slots will be functional as the traces for the pci slots come from the pci SBC connector. But it should work just fine as an Isa only system and should you upgrade to a 486 or Pentium SBC you already have a pci enabled back plane.

Reply 3 of 18, by BlackLinus24

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I know! This was my assumption as well and thought that this could be the ultimate flexible Retro-PC. Having the board in an AT or ATX case I thought this could be one of the most convenient ways of changing retro-PC configurations. You basically just change the SBC and boom you have a completely different system. The only constant extension card would be the ISA soundcard. Here and there you might have to swap the COM mouse for a PS/2 or USB but I find the flexibility of this system amazing. Would be curious to hear more from other people's experience with his concept.

Last edited by BlackLinus24 on 2019-01-18, 16:04. Edited 1 time in total.

Reply 5 of 18, by dionb

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I have a significantly earlier, more eccentric Wyse 386 "SBC" (actually two ISA boards connected both via ISA bus (for power) and a sort of bridge card, and then one of those two boards itself consists of two sandwiched PCBs) and have been able to boot it on a regular PICMG backplane that previously contained a P4. It only boots about one time out of 15, but I'm pretty sure that's to do with loose connections somewhere, not anything related to the backplane.

Reply 7 of 18, by BlackLinus24

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I got the SBC today. What I didn't know or see when I ordered it is that is has 2 PS/2 ports which was kind of unexpected. Turns out the SBC is from the British company ICL (defunct in 2002). It features an 385 33 chip which as far as I understood was primarily useful when using a NOS (Network Operating System). The board is larger than expected but in pristine condition. I guess the Lithium battery (dating from 1992) needs to be replaced.
Here some photos from the SBC.

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Reply 8 of 18, by BlackLinus24

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Regarding the backplane I was wondering if anybody knew or had experience regarding voltage setting. Do I have to do something here. What are the functions of these screws?

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Last edited by BlackLinus24 on 2019-01-19, 19:46. Edited 1 time in total.

Reply 10 of 18, by dionb

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BlackLinus24 wrote:

Regarding the backplane I was wondering if anybody knew or had experience regarding voltage setting. Do I have to do something here. What are the functions of these screws?

The screws are for alternative power options. You can screw down wires under the screws. Not needed if you're using P8+P9 anyway.

Btw, the 385 is a cache controller - basically the core part of the motherboard chipset.

Also you'll have to do something about the RAM - 386DX have a 32b memory bus, so with 30p SIMMs they need their RAM in matching quads. With only two SIMMs, the first bank is only half full here. You need four the same to be able to boot.

Reply 11 of 18, by BlackLinus24

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@ dionb
Indeed, thanks for confirming. I was actually wondering about that. Excited as I was when I unpacked the SBC I just put in the only 30p SIMMs I have.
Thanks for pointing it out!

Reply 12 of 18, by BlackLinus24

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@ dionb
Just to make sure I understood correctly. So I have two 4mb 30p SIMMs installed right now. In order for the SBC to boot I will need to install another 2 4MB SIMMs? The 4 SIMMs need to be of identical size and speed (60, 70 or 80 ns)?

Thanks!

Reply 13 of 18, by Baoran

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BlackLinus24 wrote:

@ dionb
Just to make sure I understood correctly. So I have two 4mb 30p SIMMs installed right now. In order for the SBC to boot I will need to install another 2 4MB SIMMs? The 4 SIMMs need to be of identical size and speed (60, 70 or 80 ns)?

Thanks!

Yes, you need 4 identical simms when using 30pin simms because each simm has 8 bit data bus and the cpu has 32bit data bus. 4x8bit=32bits. So four 30 pin simms makes a one 32bit bank. You can use four 1Mb simms too if you don't have four 4Mb simms because for a 386 4Mb is usually plenty.

Reply 15 of 18, by BinaryDemon

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I'd be more interested in a backplane that only provided power to SBC's so that I could put 4x SBC's into one case and create an instant doom lanparty.

Check out DOSBox Distro:

https://sites.google.com/site/dosboxdistro/ [*]

a lightweight Linux distro (tinycore) which boots off a usb flash drive and goes straight to DOSBox.

Make your dos retrogaming experience portable!

Reply 16 of 18, by BlackLinus24

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@ dionb
Just out of interest. So the remaining 4 banks need to be fitted also with identical SIMMs. If the first 4 banks already take up the 32bit bus what about the remaining 4 then.

Also, I know it's non-sensical with a 386 CPU but just I was wondering if with this backplane a PCI graphics card could be used in combination with the SBC. I do assume that the PCI and ISA slots are connected to one another, aren't they?

Reply 18 of 18, by cyclone3d

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BlackLinus24 wrote:

@ dionb
Just out of interest. So the remaining 4 banks need to be fitted also with identical SIMMs. If the first 4 banks already take up the 32bit bus what about the remaining 4 then.

Also, I know it's non-sensical with a 386 CPU but just I was wondering if with this backplane a PCI graphics card could be used in combination with the SBC. I do assume that the PCI and ISA slots are connected to one another, aren't they?

Yeah, if you want to add more RAM after the first 4 slots are filled, you will need another 4 sticks of RAM.

Nope, PCI will not work as your SBC doesn't have a PCI bus.

Yamaha YMF modified setupds and drivers
Yamaha XG resource repository - updated November 27, 2018
Yamaha YMF7x4 Guide
AW744L II - YMF744 - AOpen Cobra Sound Card - Install SB-Link Header