VOGONS


First post, by spark2k06

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Hello,

I present the following project that I have started to develop:

Universal-ITX-Backplane.png

The initial use I had in mind for it is to be able to host the Micro8088 or Xi8088 projects of Sergey Kiselev, to which we should add the rest of internal ISAs without brackets for their correct operation. However, as I was placing components I have realized that one could go further. In the area of ​​the I / O shield would be fixedly a VGA with MonochromeVGA integrated, and two DB9. These will then be used internally to connect to two serial ports on PC (COM1 and COM2), or a serial port and a standard Atari Joystick, etc ...

It would also have a 16-bit PC / 104 socket. This would serve, in addition to being able to put a VGA in this format, other cards or even a complete 286/386, which as there is available a 16-bit ISA with bracket would give game. If the PC / 104 is not used, you would have another 3 internal 8-bit ISAs available ... for example to place the low-profile RTC I designed or the Internal OPL3 sound card also low-profile I designed, and with the HDAudio connection you could connect to the front of a case of this format, many current cases already have it.

The idea, with some additional holes added that will serve as a support to add a second PCB higher in the I / O shield to add, this time, concrete things for which project. For the PC you could add a Compact Flash with its corresponding IDE connector, a parallel port, etc ...

Other projects adapted to either of the two formats could be added (as MiSTer FPGA DE10-Nano), although PC / 104 is more compact in height and would perhaps allow its use in slim type cases.

Official Mini-ITX measurements: 170 mm (length) x 170 mm (width)

Customized to locate ISA1 external slot, and give margin to the other connectors: 184,899 mm (length) x 181,026 mm (width)
To take into account when purchasing a Mini-ITX format box for the project

More info in the project URL of my Hackaday account:

https://hackaday.io/project/175340-u...-itx-backplane

Project sources on my GitHub:

https://github.com/spark2k06/Universal-ITX-Backplane

Ideas, suggestions as always are welcome, because this is in full development.

Last edited by spark2k06 on 2020-10-20, 09:02. Edited 8 times in total.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 1 of 9, by imi

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I like this a lot and had similar ideas previously ^^ though my motivation isn't high enough atm to actually go through with it.

did you think about making it mini-DTX instead, adding another regular ISA slot below the SBC slot?
there is a lot of ITX cases that have 2 card slots so you could mount one card with bracket at least, and seeing as this is a custom design anyways, adhering to standards isn't the most important ^^

Reply 2 of 9, by spark2k06

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imi wrote on 2020-07-15, 11:56:

I like this a lot and had similar ideas previously ^^ though my motivation isn't high enough atm to actually go through with it.

did you think about making it mini-DTX instead, adding another regular ISA slot below the SBC slot?
there is a lot of ITX cases that have 2 card slots so you could mount one card with bracket at least, and seeing as this is a custom design anyways, adhering to standards isn't the most important ^^

The case where I want to mount it only has an available slot, it would not fit in Mini-DTX format. The board I am designing is not exactly Mini-ITX, it is a little (very little) wider... so that the ISA slot fits in the only available slot in my case. I just left it written in the first post of this thread, so there is no doubt about it.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 3 of 9, by spark2k06

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Integration tests in a high profile Mini-ITX case and Micro8088 board inside:

https://photos.google.com/share/AF1QipM8HTva8 … XdlODItTUxIV0pn

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 6 of 9, by spark2k06

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Still in development but is taking shape. I have not yet come up with the design of a PCB for the upper part of the I / O ports, as well as a shield for this one also in PCB format for it ...

https://www.youtube.com/watch?v=EKXY5dlXFwU

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 9 of 9, by dionb

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Wonder if this project is still alive?

This week I finally found time to solder my board.

Conclusions:
- read the *)&(*& errata before soldering. Saves having to de-solder a transistor, mess around with its legs and re-solder 😉
- the LEDs use the square hole for the cathode, not the anode (as I'm used to). It's not totally standardised, so I'd suggest in a future revision to explicitly mark polarity on the PCB silkscreen to be sure.
- speaking of LEDs, the voltages on three out of four seem off on my board. Only the +12V lights up fully, the others are very dim. Could be a design issue, could also be the very wide tolerance (20%) resistors in series (I ordered the board plus components and they weren't expensive) although I measured them as pretty near 10k Ohm, so don't think that's the issue. Will be experimenting with a few differnent resistors to see what's going on.
- the board is ITX as promised. Not mITX. Doesn't fit into mITX-only cases. Fortunately it's perfect in a low-profile uATX case, with the extra slots useful for various connectors off the SBC.
- but most importantly: IT WORKS 😀

QqxGtXNks9dUEgn9uF7X0vij.jpg?f=user_large

Now moving on to using it; have it installed in an AOpen low profile uATX case with an AudioExcel CMI-8330 sound card (SB16 compatible) that fits nicely at low profile. All I need to do now is get an ATX backplate and make a low-profile backplate for the sound card, and another for the onboard NIC on the SBC and I'm good to go. Oh, and get a quieter fan for the PSU - with everything elses passively cooled, its noise is very noticeable.