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3 hours ago
1
(note: please use firmware v3.0.1, which fixes issues with MPU emulation in SB and USB modes)
New features/changes
CD-ROM emulation
PicoGUS now supports CD-ROM emulation (in other words, PicoGUS is now an ODE)! It emulates a Panasonic/MKE interface and drive and supports CD images in ISO or BIN/CUE stored on a USB drive plugged into the USB port on the PicoGUS. CD-ROM emulation has been tested in DOS and Windows 9x and CD audio playback is fully supported.
CD-ROM emulation is available in Sound Blaster and USB modes. Sound Blaster mode really pushes the limit of the RP2040: it mixes CD audio, SB DSP, and OPL sound while simultaneously supporting CD data and MPU-401 emulation. The emulated drive is approximately 2x speed in SB mode and 3x-4x speed in USB mode. Disc images can be swapped on the fly with pgusinit, and multi-disc games are supported by removing and reinserting the USB drive to advance the current disc image.
For more information and a guide on how to use CD-ROM emulation on PicoGUS with recommended drivers, known limitations, etc., visit the new CD-ROM emulation wiki page.
Massive thanks to Kevin Moonlight (yyzkevin) for reverse engineering the Panasonic/MKE interface and contributing the bulk of the underlying code for this emulation.
Also major thanks to rppicomidi for greatly improving mass storage speed for the RP2040 in TinyUSB and Artem Vasilev (wbcbz7) for additional fixes and rebasing on a more recent state of the repository. Without their work, USB mass storage would not be nearly fast enough to support CD-ROM emulation on the RP2040. These improvements are still not merged into the upstream project, so here's hoping that can be completed.
And thanks to all who tested this firmware before release to surface bugs and edge cases I wouldn't have been able to find myself. Cue sheets are the wild west of formats!
Tandy/CMS modes combined into new PSG (programmable sound generator) mode
To reduce firmware size and prepare for future support for other PSG sound chips (here's a hint, it's the AY-3 as used on the Mindscape Music Board), Tandy and CMS modes have been combined into a single PSG mode. It can be selected with pgusinit /mode psg, but the old /mode tandy and /mode cms switches still work for backwards compatibility.
Fixes
pgusinit
When pgusinit couldn't detect a PicoGUS, it would erroneously continue trying to configure the card. This would result in a strange firmware version mismatch error. This has now been fixed.
Known issues
Sound Blaster mode
Due to the addition of CD-ROM emulation to SB mode, SB DSP audio now runs through a FIFO. This may result in some playback issues that are being worked on. Also "Direct DAC" mode (mostly used by older titles) is not currently supported.
General
Due to the addition of new settings, any saved settings done with /pgusinit save on previous firmware versions will be reset to defaults when upgrading to firmware v3.0.0.
