WDI to IDE adaptor (5)

[Mike Arnold]

Hi folks, I have completed the diagnostic ROM for the W2I and the files are attached. This will enable anyone who constructs the S100 board or hand wires a board to sort out any snags.

Aron, I think that this is the last item that I needed to deliver. Let me know if you need anything else (including advance payment for the PCBs).

I am away for a few days so apologies in advance if I am slow in responding to any questions.

Mike

[Aron Hoekstra]

Wow this is really pro-level documentation, a diag rom like this will make testing and setup so much easier - I need to get to work on wrapping up the board!

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[arnold.mike@talk21.com arnold.mike@talk21.com]

I think that my former business life has stuck with me for documentation. Sorry that it all took so long.

From: Aron Hoekstra
Sent: Jan 24, 2026 at 5:07 PM
To: crom...@googlegroups.com
Subject: Re: WDI to IDE adaptor (5)

Wow this is really pro-level documentation, a diag rom like this will make testing and setup so much easier - I need to get to work on wrapping up the board!

On Fri, Jan 23, 2026 at 11:04 AM 'Mike Arnold' via Cromemco <crom...@googlegroups.com> wrote:

Hi folks, I have completed the diagnostic ROM for the W2I and the files are attached. This will enable anyone who constructs the S100 board or hand wires a board to sort out any snags.

Aron, I think that this is the last item that I needed to deliver. Let me know if you need anything else (including advance payment for the PCBs).

I am away for a few days so apologies in advance if I am slow in responding to any questions.

Mike

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[Aron Hoekstra]

Oh no problem at all, I've been draggin my feet as well working on some other projects.

[Aron Hoekstra]

Ok I think I've incorporated all your feedback. Before I start manually routing power rails, I wanted to run this layout by you first & get your thoughts/opinions. Any changes? I went through my pile of 2.5" drive and noticed there are 2 different mounting patterns so I've added holes for both styles. I moved everything in off the edges a bit to account for guide rails, etc. 

[Peter Higgins]

Mike - have you tried using a CF card with a CF-to-IDE adapter in place of a spinning hard drive or SSD drive with your prototype?

[arnold.mike@talk21.com arnold.mike@talk21.com]

Hi Peter

Yes. I bought a number of adaptors (to 40 pin IDE). That included an SD card adaptor which works well and opens up the opportunity to mail the cards as drives to friends without worries.

My dev system now uses my first prototype board with a SSD drive and that works well (hd0 & hd1 CDOS, hd2 68000 Cromix and hd3 Cromix Plus.

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[Peter Higgins]

That is good to know - thank you!

I don't know if Aron has done any of the routing yet for this board but if he needs more space, then dedicating just half the space required by an SSD or spinning drive with use of a CF/IDE adapter could be considered.

[Mike Arnold]

Hi Aron, back from my holiday and I have looked at your layout. A few minor points:

1. Suggest add TP14 GND next to TP13 as an additional ground point.

2. Cosmetic: the fault LED is part of the IMI signal set so you could consider moving it next to flush. This leaves IDE, SEL and ROM as W2I internal signals.
Looks really good. I will be interested to see if Kidcad prefers the new chip layout. Can't wait to get my hands on a board.

Peter, I think your idea for an on-board SD (CF) adapator is good but the adaptors that I have seen don't easily fit on to a pcb. If the adaptor is external (on the 40w ribbon plus a +5V line) then it can be positioned for easy access to the card slot - maybe outside the chassis. Therefore, I suggest we keep to the original plan. 

Regards, Mike.

[Peter Higgins]

This is what I had in mind for mounting of a CF card adapter directly to the PCB:

https://www.s100computers.com/My%20System%20Pages/IDE%202CF+SD%20Board/IDE%202CF+1SD%20Board.htm

...which only requires soldering a common 2x20 pin right angle header to the board.

The CF card sockets themselves are of course also available separately - see DigiKey part number SAM9213-ND. These are designed for through-hole soldering directly to the PCB for an even more compact design. Soldering these requires a wee bit more skill due to the fine pitch of the pins.

The original design is, of course, perfectly fine.