Oh uh,at this point I know a fair bit about how the memory is wired up on the Interwave: Upgrading Philips PCA761AW / AMD Interwave 'GuS Clone' to 1MB RAM
I'm not messing further with my Philips PCA761AW card now, but I think I know how the memory wires would all connect up with 8/16mb of RAM using SoJ chips harvested from 72-pin simms. It's something that I would kind of like to do - the 8mb RAM wiring is kinda planned out in my head from how it could connect to the PCA761AW, but I've had little impetus since I got this working GuS PnP alternative and gave it enough memory to do what I wanted.
I can route traces on a PCB, though I don't know much about analogue electronics so I'd probably just use an audio section from another open source project for reference.

The original mask ROMs can be bought easily enough, does anyone know of a good source for the AM78C201 chips at this point?

Thermalwrong wrote on 2021-12-11, 01:37:

The original mask ROMs can be bought easily enough, does anyone know of a good source for the AM78C201 chips at this point?

For the AKC, there currently only seems to be one seller on that well-known auction site. The older KC is available from utsource, don't bother inquiring them for the also listed AKC - I've done that numerous times, it's always out-of-stock in the end.

I'm still here. I have parts for 3 boards so I will have to make PCBs for myself if no one else will make them available. I'm teaching myself Sprint Layout for that eventuality. If I do end up doing this they will go directly to github of course. But I'm still some way off that happening. Hope you all had a good holidays even if you are gravis..less

has shock walked away from this project?

Sev80 wrote on 2021-12-27, 23:04:

has shock walked away from this project?

Probably got severe project burnout. I've had it before, you usually don't recover or have anything to do with something again once that happens. But it's ok, understandable

elfoam wrote on 2021-12-28, 05:17:

i

Sev80 wrote on 2021-12-27, 23:04:

has shock walked away from this project?

Probably got severe project burnout. I've had it before, you usually don't recover or have anything to do with something again once that happens. But it's ok, understandable

I didn't know that the prototype phase would be my only chance to get a card or I would have ordered some then. I backed the project, so I'm hoping there can at least be more orders of what's been done so far...

Okay, I'm gonna have a go.

The audio output section is going to be using the headphone amp design that the megagrrl player uses - because I have a schematic for it, I can compare it with working ones (it sounds great) and the parts are all commonly available.
I've got my Philips card to compare parts with - I've already played about with my card and got a much better understanding of how memory can be arranged on it.

I'm hoping that it could all be SMD, so it can be easily assembled and maybe scaled up with a pick'n'place. I've assembled enough through hole cards at this point that I really want to just stencil on solder paste, install most of the components then cook in the reflow oven (I don't have a reflow oven yet or much experience with such things yet...).
Memory would be soldered to the card using HT511740ASJ-60 SoJ modules taken from 72-pin SIMMs (2x 4-bit modules per bank), that can be put on as needed up to 16MB - or 8 modules.
This design will be using the original IW78C21M1 mask rom that can be purchased online still.

The plan is to make this available for people to put together themselves, kinda like the Snark Barker or HardMPU projects. I don't think this will affect values of the now extremely rare original cards - it will probably only be viable for as long as we can find working AM78C201KC chips.
So far, I haven't observed the Snark Barker cards tanking the value of the CT1320 original cards - they're difficult and expensive to put together, so the cost is near to what an original costs at ~£100.
If you see this shock__, thank you for your work on this, the information you've shared has been awesome for expanding my understanding of how the Interwave card works and the memory links together. Hopefully I can make a card that's nearly as good as the Argus.

GuST - Gravis Ultrasound Tribute?

Lovely! We are designing our own ultimate GUS here too, but the project is on a hiatus due to other priorities. Our idea is to integrate a YMF71x for the SBPro/Adlib compatibility and to mess with the ROM. If we dropped the ROM enhancements, we would advance at a good pace already, so maybe it can happen at some point, as it is a bit too complex, involving an additional MCU (we are messing with STM32) and a "bit" of code.

GUST has a nice ring to it - in theme with other projects 😉

I don't think that ArGUS nor GusAr put a dent on the GUS marketplace. If not, they may have influenced the prices as more people reminded themselves of the ol' card. Also I'm with you on the SMD part - both for convenience and that SMD would be more fitting for the card's looks.

Best of luck - I assume many others like me wanted a new GUS clone but didn't manage to sign up in time.

I doubt those AM78C201KC chips are going to be around much longer, after that it's going to have to be a FPGA recreation.

If we forego the original chipset, I would just focus on the synthesizer aspect of the GUS. Most software that requires GUS is not concerned with the other features like game port, ide controller or codec. As most people combined the GUS with another card anyway, why implement features that will be disabled immediately because people have a second card that does them better?

digistorm wrote on 2021-12-29, 08:26:

why implement features that will be disabled immediately because people have a second card that does them better?

I think I agree with this. Sure it would be a great card with GUS + YMF71x or some other good SB pro controller combined to a single card. But I think most useful would be something like GUS ACE + PCMIDI (intelligent mode MPU + wave table header) on a single card. That would be really useful with any Sound Blaster or compatible card on just about any 386 and later ISA system. I definitely would like a card like that on my retro systems.

Okay, this GUSt thing is coming along. I only know Fusion 360 + EAGLE. I've designed a few PCBs now, making some HardMPU cards and some risers. Kinda need to learn KiCAD at some point though, it seems easier than the disjointed mess that is the half-cloud, half regular application that 360+EAGLE now is.

I think the free version of EAGLE / 360 that I'm using limits the PCB to this size. Which should be fine, enough to fit a decently sized 16-bit ISA card.

I've got the Interwave chip and the RAM I want to use in EAGLE as complete components, so now to add some more parts.

The ROM is the next tough one, not sure yet what part - I think it's related to the Macronix MX29L3211MC, but with a different capacity, pinout (potentially) and voltage. They're both SOP-44 at least so I can use that for package dimensions.

Then I can start dismantling my Philips Interwave card, probably mostly copying the layout of that. But shock_ has already done a lot of that work, so I will probably be referring to the ARGUS BoM for resistor / capacitor values where it can help.

I like the sound of GUSt as well, and I think the high prices an original GUS commands on eBay means interest will likely be strong for a project like this.

It's funny, about 20 years ago it was rare to find a GUS on ebay. But when they did pop up every several months they were only $15-30. I bought quite a few of them back then. These days they are constantly listed on ebay but the prices are nuts.

Plasma wrote on 2021-12-30, 21:37:

It's funny, about 20 years ago it was rare to find a GUS on ebay. But when they did pop up every several months they were only $15-30. I bought quite a few of them back then. These days they are constantly listed on ebay but the prices are nuts.

Yeah, there is that one seller in Hungary who seems to have several in stock and is slowly selling them one or two at a time to keep the price high.

🎵 Like a gust of wind you head me off sometimes
Like a gust of wind you push me back every once in a while
Like a gust of wind you remind me there's someone up there
Who ushers in the air I need to power my sail 🎵

https://open.spotify.com/track/5m6F6glTwHhsol … fb713c42bc247ee

By the way, Happy New Year everyone 😄

Another day spent on GUSt 😁

I've partly dismantled my card to figure out what each voltage regulator does and how it hooks up. The 7905 negative voltage seems to be only for the Mic input? That's going to be optional I think.
Here are front & back scans from my card if anyone else would like to refer to them:

What's under the chips can be found on shock's blog.

The Line out of the Interwave looks like it will connect straight up to a regular headphone amp, the one I plan to use is a TPA6111A2. That's used on another open source project and it sounds great, so it should work well for this card.

At this point, I think I've got all the nets for the memory, ISA bus and Interwave chip.
Trying to work out how the AGND links to the DGND and the Philips card uses a pointless 0ohm resistor. The STB Interwave uses an inductor though, so I'll probably go that way.
Here's the front & back of the STB interwave, taken from Clous's website:

To-Do list:
PNP EEPROM
Line In, Mic and Line Out sections
Gameport & 3.5mm jack placement
Resistors & capacitors
Routing traces 😁

Does the IW78C21M1 part number determine a masked ROM for GUS? There are still several places I can buy this chip but I am wondering if the ROM mask could be different.
Please advise or indicate the proven source where I can buy the right version of that chip.
Thanks.

jaca_kk wrote on 2022-01-27, 14:44:

Does the IW78C21M1 part number determine a masked ROM for GUS?

Yes, that holds the ROM-based 1-MiB instrument bank. To my knowledge, there is only one version of that ROM; at least, on every board that has been mentioned here, the ROM contents have been verified to be exactly the same. If another version was ever released, nobody here has ever mentioned it. If you search this thread, you will find the exact UTSource page from which a number of participants have sourced the original ROM. At least so far, nobody has complained of defective chips or different/corrupt content, so as long as the part is still available, that should be a good source.