Re: DIY ISA backplane

[Sergey <skis...@gmail.com>]

Martin,

Thanks for your input!

I designed an ATX power switch circuit using 74LS74 and 74LS14...
While it takes more space than ATtiny13 and probably costs about the
same, there is no added complexity with programming the
microcontroller. So prefer this design.

Yes, it will have an on-board LED for power (maybe even 5 LEDs for all
voltages) and on-board power switch as well as headers for a power LED
and a power button.

The RESET signal on ISA is a regular TTL signal (not an open collector
signal) driven by the CPU board. So it is not possible to drive it
from the backplane. But it is possible to add a reset button and
header to connect it to the CPU board. (Note: My CPU board does have a
reset button on it, in addition to the reset header).

Thanks,
Sergey

On Sep 25, 1:31 pm, Martin Lukasek <martin....@artax.cz> wrote:
> Hi Sergey,
>
> that sounds good, put me down for one too, please. I was going to suggest ATX power supply with some ATtiny13 or similar power on/off circuit and -5V power supply, but you already did. It would be nice to have pin headers for front panel LED(s) and RESET button, as well as Power ON button and it is also useful to have these two small buttons on the backplane while testing out of the case.
>
> Best regards
>
> Martin
>
>
>
>
>
>
>
> -----Original Message-----
> From: n8...@googlegroups.com [mailto:n8...@googlegroups.com] On Behalf Of Sergey
> Sent: Tuesday, September 25, 2012 9:44 PM
> To: N8VEM
> Subject: [N8VEM: 14716] DIY ISA backplane
>
> Hi,
>
> Several people asked me about getting an ISA back plane. While it is possible to buy one, some folks would like to build one themselves.
>
> So I am wondering how many people would like to build one?
>
> Also I would like to collect various ideas for making the backplane.
>
> Here is what I have in mind so far:
>
> - Minimally sized Micro ATX board  (9.6" x 6.7" or so). It is possible to make the board even smaller, only using the PCB space needed for connectors and other components, but yet keep the ATX - compatible mounting holes.
> - 5 or 6 ISA slots. Note that Micro ATX only allows 4 slots, so if using a case only 4 slots will be exposed on the back side. But still it should be possible to use the remaining slots for cards that don't have connectors on the back side, for example the XT-IDE card.
> - ATX power connector and power on circuit (so it will work with a momentary switch normally found in ATX cases)
> - Minus 5V regulator (convert -12V to -5V). Most modern ATX power supplies don't provide -5V (it is optional), but yet some ISA cards use it. This circuit could be optional with a jumper to select -5V source (ATX power supply or the backplane regulator)
> - Onboard FDC and UART... maybe a couple of UARTs. I am not sure about this one... an alternative would be making an FDC/UART ISA card, which is more universal approach. I this case it is possible to provide two DE9F serial port connectors with 5x2 headers connected to them (for example to plug the XT-IDE V2 serial interface).
>
> Any suggestions?
>
> Thanks,
> Sergey
>
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