So, where do you plan on connecting the 12V power brick? Does the SBC take that directly and makes it's other necessary voltages?

Oh, the picoPSU, I get it now, thought that was the name of the power brick 🤣 my bad

Yes, the SBC can be powered either via the ISA bus, or via a floppy style power header. I'll be using the latter.

Made a decision on the case - I'm using maple for the top and bottom panels, with a darker acacia wood for the front, rear and sides - I wanted a contrasting colour rather than being the same on every face. Boards have been ordered and are on their way.

I also just had a Pi Compute Module 4 delivered today, to be used for a WP32 McCake setup, but am holding off on ordering the McCake itself, as Serdashop can only send via business post to the UK at the moment (and it means post is almost the same cost as the McCake itself).

I love tiny systems. I’ll be very interested to see how this comes together.

- Alex

You'll need to test it out, but that floppy connector will only supply +5V and +12V, I'm not convinced it will power the whole ISA expansion board and do voltage conversion. It's possible, but test the board by itself first. And then plugged into the riser without any other cards and test that you have the various power rails.

It might make sense to create a small PCB that has a 90 degree ISA slot, and 90 degree ATX power socket. Then you can pull power directly from the PicoPSU and only have the floppy drive, and McCake drawing power rather than all of it passing through that single cable, it will also cover the energized edge of the riser. You could also add a simple header to connect a switch to actually power the machine on.

Are the pictures of the actual card you ordered? I wonder with that CN5 connector at the bottom is. I'm wondering if it's like a PC/104 connector. Maybe it would be possible to connect a SoundBlaster type card there like the Vortext86 uses to have digital audio, then you'd have room for a PicoGUS which will give you GUS and a real MPU401.

Yes, it is indeed a PC/104 connector. Fortunately I already had the ES1868F, so that was a zero cost option for me.

Sadly my GUS Max and AWE32 are going to have to go into storage as well. When I bought the GUS (new, when they came out) I used it extensively, alongside a SB2.0, but these days it's Roland gear, almost exclusively (either real, or via MT32pi). The GUS is currently in a 486DLC and I found I just don't use it.

The picture is of the same model card, but not mine. Mine appears to have a decent capacity simm installed (double sided, at least 16 chips), as well as a CPU with heatsink and fan (so I'm guessing at least a DX4 - though I have an AMD X5 133 in my spares).

The SBC manual mentions using the onboard power header instead of the ISA interface... but it is curiously short on details of the pinout. We would assume it is standard floppy pinout..... but in the worst case with the power, I can solder the main AT voltages direct to the riser card, as I've left plenty of room between the back of the card and the case for mounting hardware.

megatron-uk wrote on 2024-02-24, 18:23:

Sadly my GUS Max and AWE32 are going to have to go into storage as well. When I bought the GUS (new, when they came out) I used it extensively, alongside a SB2.0, but these days it's Roland gear, almost exclusively (either real, or via MT32pi). The GUS is currently in a 486DLC and I found I just don't use it.

If you're mainly going to play games rather than just tinkering and generally MIDI, then your setup should be fine.

I just mentioned the PicoGUS as it gives you not only a GUS in a small form factor but also hardware IRQ MPU401 support so you don't need to mess with SoftMPU for those MT32 games that need it, and error an error-free external MIDI port. It's also flashable on the fly to be an OPL2 Adlib card, CMS Gamebaster, or Tandy 3 voice. It's a crazy Swiss Army Knife for the various music options in DOS games. It's just missing the digital audio side of things, SB support is being added, but I'm not sure if it will be able to do SB digital audio and something like GUS at the same time. So right now, it pairs best with a 16-bit SB that can also do OPL3. But it might make sense to keep an eye on what it can do in the future.

Indeed, if it had SB/Pro/16 digital support then that would be a hell of an all-in-one option, and certainly one to consider if you wanted a single slot solution.

I'll probably keep my (real) MT32, SC55 and SC8820 out on the shelf for use in Dosbox and with my (real) X68000 and PC-98. Everything else I can do with Dosbox and this little 486 system (a lot of dev work I do in Dosbox, but testing on real hardware is always a key criteria). I therefore free up 3 mini towers and 1 desktop case worth of desk-top and under-desk space. It was getting quite cluttered!

Realtek 8019AS ISA card arrived today. Waiting for the 486 SBC to complete the stack of ISA cards.

Wood for the case has arrived:

Shipping tracker for the 486 SBC is showing that it should be arriving tomorrow.

486 SBC arrived this morning. No damage, and CPU and RAM installed as shown... but... wow, it stunk!

Definitely been used in an industrial setting - the smell was like burnt metal. It has clearly seen many years of use (date code on the stickers on the chips says 4th of 5th month of 2000). The cpu fan screws are rusted out, and the backplate, while not rusted, had definitely started to wear the zinc coating off the metal. So the entire board has been washed in 99% IPA, and it's feeling (and smelling) a lot better, I also rubbed down the IO plate with 500 grit paper. It also uncovered the CPU, which is a DX4-100:

Here's the setup of the stack now:

... and in a possible vertical case alignment:

Next is to get it plugged in and tested. I'll probably do this with it as a standalone card, before it gets plugged into anything else.

Also the silkscreen on the board confirms that the alternative power connection is a standard +5/0/0/+12 terminal - i.e. a 4 pin mini-spox/3.5" FDD power cable matches perfectly.

Once you get it working standalone, plug it into the backplane by itself and see if you have the -5V and -12V power on the other ISA slots.

I see a single transistor, which is likely generating 3.3V for the CPU. But I don't see anything that would generate the other voltages.

https://upload.wikimedia.org/wikipedia/common … SA_Bus_pins.svg

Yes, I am fairly certain the only voltage conversion going on is via that regulator for the processor socket. Nothing else I can see.

I don't need -5v, that I'm aware of, but I had a feeling -12v was used more commonly. I can always take it from the atx pins on the Pico connector if needed.

-5V was mainly used by older sound cards, the ESS is likely new enough, but you never know.

-12V was more commonly used, check the pinout Wikipedia link I posted and then look at your cards. They generally won't have a pad on the slot if it doesn't use the voltage, so you can check your sound and network cards.

Following this project!

SScorpio wrote on 2024-03-03, 00:18:

-5V was mainly used by older sound cards, the ESS is likely new enough, but you never know.

-12V was more commonly used, check the pinout Wikipedia link I posted and then look at your cards. They generally won't have a pad on the slot if it doesn't use the voltage, so you can check your sound and network cards.

Okay, looking at the 8019AS NIC it uses neither -5v or -12v; pads B05 and B07 are both missing.

On the other hand, with the ESS ES1868F sound card, whilst B07 / -12v is missing, it does have a pad for B05 / -5v. However, there are a lot of missing, optional components on this card and I see no amplification circuitry of any kind - there is just the ES1868F chip, an oscillator, some electrolytics and a small handful of (i think?) inductors. The card also doesn't have a labelled speaker out (just line out).

I strongly suspect that B05 / -5v is there for optional onboard amplifier for a speaker-out connection with this card. The ES1868F chip datasheet doesn't show any -5v DC requirements for the chip itselfthe only mention of input voltages are a VDDD pin (digital voltage +) and VDDA (analogue voltage +4.5v to +5.5v DC).

Although, now digging deeper, the waveblaster header specifies a -12v DC voltage on pin 22.... this would mean that this card technically doesn't meet the requirements of hosting a waveblaster daughterboard.

I only have a NEC XR385 (which I won't be using - far too big), but am planning on getting a WP32 McCake in the near future. I'm wondering if that would actually need the -12v line...