Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-10-31, 15:45

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by polpo

in Marvin \ Sound

in Marvin \ Sound

yesterday I've got a PicoGUS PCB as a gift and because of that I became interested in this topic and then I thought - why not go PC/104? What do you think? Can I make it? I am not sure about the license stuff... Kept everything the same, just added my name as a "modificator" Wow! This is so cool to …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-10-19, 03:15

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by polpo

in Marvin \ Sound

in Marvin \ Sound

So the beta PCB I've designed, and I've sent a few boards out to testers in North America. A few other people have fabricated their own boards as well using the KiCAD project I have on my Github. If you search picogus on Twitter you'll see them! I'm not confident enough in the design to say it's …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-10-17, 19:38

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by polpo

in Marvin \ Sound

in Marvin \ Sound

Usage of DMA for sample upload by demoscene productions is much more rare than games, but there are a few that do it. Inside by CNCD (but that can be disabled in setup) and Stars by Nooon are two that come to mind. Several module players like Capamod and Cubic Player also use DMA for sample upload …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-08-15, 17:06

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by polpo

in Marvin \ Sound

in Marvin \ Sound

I think you did not implement the IOCHRDY Signal on the Pi3 board, It can explain the problem. I'd like to go back eventually to the Pi3/4 and look at that. I can't trigger IOCHRDY in software on a Pi3/4 as fast as the RP2040 can in PIO, but I'm pretty sure I can at least drive it low within the …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-08-09, 19:30

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by polpo

in Marvin \ Sound

in Marvin \ Sound

I haven't measured power consumption... I currently have the Pico overclocked to 270MHz, at the default Vreg of 1.1V and the RP2040 is cool to the touch with no heatsink. From other people's data on overclocking the RP2040, the Pico should be consuming less than 40mW at that speed and Vreg. There …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-08-09, 16:10

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by polpo

in Marvin \ Sound

in Marvin \ Sound

GUS emulation on the Pico is working great and the Pico has no problem mixing 32 channels of audio, especially if it is faithful to the GUS and reduces the sample rate as the channel count goes above 14. I am using external SPI PSRAM to support the full 1MB sample ram for the GUS. Here is a video …

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Re: Orpheus II soundcard thread

Posted on 2022-07-18, 14:59

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by polpo

in Marvin \ Sound

in Marvin \ Sound

When I saw the length of the card and the SIMM slot location, my first thought was that it was an AWE clone... then my eyes moved down and saw the Interwave. Amazing work! How constrained is the supply for Interwave chips? I imagine between this project and the Argus, the remaining stock left in …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-07-17, 23:03

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by polpo

in Marvin \ Sound

in Marvin \ Sound

@polpo is Back and progressing well :) Heh, I should give an update! This project has bifurcated into two projects. Yeah, I'm well aware of the perils of scope creep... The first is a cheap, accessible card, based on the Raspberry Pi Pico. The Pico is only $4 and available in unlimited quantities, …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-25, 00:31

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by polpo

in Marvin \ Sound

in Marvin \ Sound

I've found a pretty major hardware design flaw in my prototype card: the AEN signal on the ISA bus is grounded. This means the board will not cooperate with anything else in the system that does ISA DMA transfers, for example the floppy controller. Nothing I can't work around with some trace cutting …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-24, 21:11

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by polpo

in Marvin \ Sound

in Marvin \ Sound

What is DMA used for on the GUS? Sample upload? Recording and playback of audio? Yes, it can be used for sample upload, which doesn't really seem much faster than PIO in practice. It's mostly used for streaming audio, which on the GUS is basically setting a looping sample, getting an IRQ when …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-24, 05:34

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by polpo

in Marvin \ Sound

in Marvin \ Sound

So… for the time being I have added fixed 44.1kHz output to the DOSBox-staging GUS emulator and have also added IRQ deassertion to it. Now IRQs are working as expected. Here are a couple demos that use IRQs for timing playing on the PiGUS: Crystal Dream II: https://twitter.com/ianpolpo/status/ …

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Re: ARGUS Project thread - now accepting pre-orders (for north/south American and Europe)

Posted on 2022-06-22, 01:59

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by polpo

in Marvin \ Sound

in Marvin \ Sound

It it needed for trackers and other kinds of players that only play music? I guess I would need to test it out to be sure. From my relatively limited experience, use of DMA in demoscene productions is somewhat less common. For trackers and music players, here's what I know of off the top of my head …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-20, 16:17

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by polpo

in Marvin \ Sound

in Marvin \ Sound

By the way, I'm considering switching to the GUS emulator in DOSBox-X. While similar to the code I'm currently using from DOSBox-staging, it has a few benefits: it can have fixed 44.1Khz sound output regardless of channels, it appears to have more focus on ensuring that Demoscene productions work (a …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-20, 15:54

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by polpo

in Marvin \ Sound

in Marvin \ Sound

Anyway, back to the topic: How much CPU is currently spent emulating the GUS? Or in other words: how much spare resources are still left? Short answer: I don't really know, but I could add some instrumentation to see how much time is actually spent in GUS emulation. In the multi-core bare metal …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-17, 16:51

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by polpo

in Marvin \ Sound

in Marvin \ Sound

Small update: I have IRQ somewhat working but it is not 100% reliable yet. For example, timers are funny. Crystal Dream II runs at about 33% speed as it's reliant on the GUS timer to time the whole demo. I will be doing some captures with my logic analyzer of my actual GUS card to see how it drives …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-17, 16:47

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by polpo

in Marvin \ Sound

in Marvin \ Sound

Hi, I already contacted you in Vogons and recommended you to use my Player, Mod Master... it use only the I/O Port and no IRQ/DMA. As it also support Interwave, you can try this as well. You can't use @decoding and still have DMA Working. Also, add Tandy, CMS, OPL2/OPL3, Covox is simple as none of …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-15, 00:30

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by polpo

in Marvin \ Sound

in Marvin \ Sound

Yeah, this is an experiment that I'm doing out in the open and I'm in it for the fun of learning about the ISA bus, the GUS itself, and how far a Pi can take things. Failure is an option, and I'm fine with that. I've had a lot of fun so far. A couple projects that use a Pi that interface directly …

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-14, 20:50

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by polpo

in Marvin \ Sound

in Marvin \ Sound

I'd love to use an FPGA, and such a solution would be far better suited to emulating a GUS, but I don't know any Verilog beyond "make the LED blink." Simple as that!

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Re: PiGUS: Gravis Ultrasound emulator on an ISA card with Raspberry Pi

Posted on 2022-06-12, 14:47

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by polpo

in Marvin \ Sound

in Marvin \ Sound

so raw pi IO in bare metal mode is fast enough to handle ISA bus transactions? :o I assumed you would need pico RP2040 with PIO to respond fast enough. Add ~$2 8MB SPI PSRAM APS6404L and you could do any sound card emulation on pico Yes, it's fast enough, amazingly. It took some discussion on …

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PicoGUS: ISA sound card emulator with Raspberry Pi Pico (Gravis Ultrasound, AdLib, MPU-401, Tandy, CMS)

Posted on 2022-06-11, 21:52

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by polpo

in Marvin \ Sound

in Marvin \ Sound

This project originally started out based on a "full" Raspberry Pi but I moved to using a Pi Pico. I recommend looking at the later pages in this thread - things get going with the Pico on Page 5 . Current status: * Hardware v1.1 hardware design and gerber files are available - currently "build-your …

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