Audition, inspect, and curate Atari RMT instrument files.
PokeyForge is a standalone Windows tool for working with .RTI files — the
instrument format used by Raster Music Tracker (RMT)
on the Atari 8-bit. It lets you:
- Browse a whole folder tree of
.RTIfiles at once. - Play any instrument across the keyboard at different pitches, so you can hear what it actually sounds like without opening each one in RMT.
- Inspect an instrument's internals — its parameters, AUDCTL flags, envelope, and note table — laid out on a single screen.
- Edit an instrument in place: move a cursor through any field, type new values, rename it, and hear the change immediately.
- Collect the ones you like into a 64-slot bank, audition any slot, then
save it as both a set of individual
.RTIfiles and a single.RMTmodule that RMT can open. - Reload a saved bank later, switch between instrument libraries, and pick up where you left off — PokeyForge remembers your last library and the last instrument you were on.
The sound is produced by the exact same emulation RMT itself uses (the Altirra POKEY and 6502 cores plus the RMT tracker driver), so what you hear in PokeyForge is what you'll hear in RMT.
How edits are saved: PokeyForge never overwrites your original
.RTIfiles. Edits live in a working copy; to keep them, put the instrument in the bank (+orCtrl+Ins) and save the bank (F2). Anything modified-but-unsaved is marked orange so you can see what still needs saving.
Authentic sound
- Plays instruments through the real RMT signal chain — an emulated 6502 running the RMT tracker driver into an Altirra-grade POKEY core — so the output matches Atari hardware and RMT itself.
- PAL/NTSC clock toggle; ±octave transposition.
- Live master oscilloscope showing the channel-1 waveform as it plays.
Browse a whole library at once
- Recursive folder scan of every
.RTIunder a directory. - Multiple list views: Folders, Category, All, and No duplicates.
- Type-to-search filter bar to jump to an instrument by name.
- Automatic categorisation (bass / lead / percussion / noise-FX / pad) and duplicate detection across the library.
- Drag-and-drop a folder or a single
.RTIonto the window to load it.
Audition
- Play any instrument chromatically across the keyboard (
a–z,0–9). - Browse with the arrow keys / mouse wheel;
Escsilences without exiting. - Sample any bank slot in place with
Ctrl+ an audition key.
Inspect & edit
- Every instrument laid out on one screen: parameters, AUDCTL flags, envelope, and note table.
- Move a cursor through any field and edit with hex/decimal entry, Shift+↑/↓ nudge, or right-click bit toggles — and hear the change immediately.
- Rename instruments inline.
- Full undo / redo (
Ctrl+Z/Ctrl+Y). - Export an edited instrument as a new standalone
.RTI(Ctrl+S).
Build a bank
- Curate a 64-slot bank; copy / cut / paste / reorder slots in EDIT mode.
- Save the bank as a set of individual
.RTIfiles and a single RMT-compatible.RMTmodule (plus a manifest). - Reload a saved bank, switch libraries on the fly, and resume where you left off — the last library, bank, and instrument are remembered between runs.
Standalone & self-contained
- Single Windows
.exe, no installer and no MFC — built in C++17 with SDL3. - App icon, splash screen, in-app About and F1 keybindings overlay, and friendly error dialogs.
PokeyForge.exe "C:\path\to\your\instruments"
PokeyForge scans that folder and all its subfolders for .RTI files and opens
ready to play the first one.
PokeyForge.exe
If you've used PokeyForge before, it reopens the last library you browsed and
jumps back to the last instrument you were on. If there's no remembered
library (first run, or the saved folder no longer exists), a folder-picker
dialog appears — choose the folder containing your .RTI files. Cancelling the
dialog on first run exits the program.
You can change libraries any time with F4 (see Switching libraries below).
PokeyForge.exe "C:\path\to\bass1.rti"
PokeyForge loads the file's parent folder and jumps straight to that file.
PokeyForge shows everything on one screen — there are no separate tabs or windows to switch between. As you move through the directory, every panel updates to reflect the currently selected instrument.
+-----------------------------------------------------------------------+
| [Save F2][Load F3][Library F4][Help F1] Clock:PAL Oct:+0 Bank:03/64 | <- Menu bar / header
+--------------------+--------------------------------------------------+
| Directory | Instrument: "bass1" v1 (NN ATA bytes) file:b... |
| |--------------------------------------------------|
| v drums/ | Parameters AUDCTL [15kHz][HPF1]... |
| B kick.rti | Tbl Len : 04 ... |
| snare.rti |--------------------------------------------------|
| > leads/ | Envelope |
| bass1.rti <-- | VolR [F][F][E][C]... |
| bass2.rti | VolL [F][F][E][C]... |
| |--------------------------------------------------|
| | Note table [00][04][08]... |
| |--------------------------------------------------|
| 12 / 87 files | Bank [00-kick][01-bass][02-..][ ]... |
+--------------------+--------------------------------------------------+
| F2 Save F3 Load F4 Library | Ctrl+key sample Ctrl+Ins set Ctrl+Del | <- Command bar
+-----------------------------------------------------------------------+
When you turn on Edit mode (F6), the focused panel gets a bright white
frame and an edit bar appears above the command bar, naming the field under
the red cell cursor, its value and range, and what it does.
Panels:
| Panel | What it shows |
|---|---|
| Menu bar / header | Clickable buttons — Save (F2), Load (F3), Library (F4), Analyse (F7), About, Help (F1) — plus status (PAL/NTSC clock, octave shift, bank fill count, [EDIT] / MODIFIED), and a small live scope in the top-right corner showing channel 1's waveform as it plays. |
| Search bar (bottom of the right column) | Type-to-filter the instrument list by name (press / or click it). |
| Directory (left) | The folder tree. > is a collapsed folder, v is expanded. The highlighted row is the instrument you're auditioning. A B next to a file means it's in your bank. Long names are shortened with a trailing ~; the full filename always appears in the instrument header. |
| Instrument header | The selected instrument's internal name, RTI version, ATA byte size, and the source filename (handy when the tree truncates it). |
| Parameters | The instrument's 12 main parameters (table length/goto/speed/type/mode, envelope length/goto, volume fade/min, delay, vibrato, frequency shift) plus the 8 AUDCTL flag toggles. |
| Envelope | The 8-row envelope grid (volume left/right, filter, command, distortion, portamento, X, Y) across each step. Brighter cells = higher values. A red marker shows the envelope's loop (goto) point. |
| Note table | The instrument's note/frequency table; the loop (goto) step is highlighted. |
| Bank | Your 64 collected instruments as an 8×8 grid, each tile labelled NN-name (e.g. 00-kick). Saved slots are green; orange slots are added/edited but not yet saved to disk; the slot holding the current instrument has a red border; the selected slot (for Ctrl operations) has a yellow outline. |
| Command bar (bottom) | Quick reminders of the file/bank actions (F2 Save, F3 Load, F4 Library, the Ctrl bank verbs), the current library path, and transient confirmations like "Saved drums.rmt + 12 .rti". |
| Edit bar (when editing) | Appears above the command bar in Edit mode: names the focused panel and field, shows its current value + range, and a one-line description of what the field does, plus the editing controls. |
Press any letter or number key to play the currently selected instrument at a pitch:
a–zthen0–9form one long chromatic scale — 36 semitones in total, from low to high.ais the lowest,9is the highest.- Use
[and]to shift the whole keyboard down or up by an octave, so you can hear the same instrument in a very low or very high register.
Notes play one at a time. Each instrument plays out according to its own
envelope and fade — you don't need to release the key. Press Esc at any time
to cut the sound.
←/→or↑/↓— step to the previous / next instrument. Hold the key to scroll quickly.- Mouse wheel — fly through the list (3 instruments per notch).
- Click any instrument in the tree to select it; click a folder to expand/collapse it, or a category header to collapse it.
PageUp/PageDown— jump 10 files at a time.Home/End— jump to the first / last file./— search: start typing to filter the list to instruments whose name contains what you type. Arrows still move through the matches;Enterkeeps the filter,Escclears it.Enter— collapse or expand the folder that the current file lives in, to tidy up the tree as you work.
The directory list always wraps around — going past the last file brings you back to the first (via the arrows) — and every panel refreshes as you move.
The bank is your shortlist of favourite instruments — up to 64 of them.
Selecting a slot: click a bank tile with the mouse, or press Tab /
Shift+Tab to move the yellow selection cursor. The selected slot is the target
of the Ctrl operations below. Clicking a filled slot also loads it as the
current instrument (so you can edit it).
Adding:
+(or=) — add the current instrument to the next free bank slot.Ctrl+Ins— copy the current instrument into the selected slot, overwriting whatever was there.
Auditioning a slot:
Ctrl+ an audition key (a–z/0–9) — play the selected bank slot at that pitch. Plain keys (noCtrl) still play the current instrument, so you can A/B the two.
Removing:
-— remove the instrument you're currently auditioning from the bank.Ctrl+Del— remove the selected slot. (PlainDeletedoes nothing to the bank, to avoid accidental deletions.)
Added or edited slots show orange until you save the bank, then turn green.
Saving:
F2— opens a standard Windows Save As dialog. Type a name and choose a location.
PokeyForge then writes two things at that location:
<name>.rmt— a single RMT module containing all your bank instruments (with a silent placeholder song). Open it directly in RMT; the instruments populate the instrument table.<name>_rti/— a folder of one.RTIper filled slot (00_kick.rti,01_bass1.rti, …) plus amanifest.txt. Load these individually in RMT with File ▸ Load Instrument.
Reordering:
Ctrl+Ccopies the selected slot,Ctrl+Xcuts it,Ctrl+Vpastes into the selected slot. Cut + paste moves an instrument to a different slot.
Loading:
F3— opens a file picker. Choose either a.rmtfile (PokeyForge reads its instrument table) or a saved bank'smanifest.txt(PokeyForge re-reads the individual.RTIfiles). The bank is replaced with what you load.- The last bank you saved or loaded is reopened automatically on the next
launch (remembered in
pokeyforge.json).
Press F6 to toggle Edit mode (the header shows [EDIT]). Browse mode is
unchanged; nothing is editable until you turn this on.
In Edit mode:
- The focused panel (Parameters, Envelope, Note table, or Name) gets a bright white frame, and a red cursor marks the exact cell you're changing. The edit bar at the bottom names the field, its value and range, and what it does.
Tab/Shift+Tab— move between the four panels.- Arrow keys — move the cell cursor.
0–9,A–F— type a value (two-digit fields compose);+/-nudge by one.- Right-click any binary field — an AUDCTL flag, the table type/mode, or an envelope filter/portamento cell — to flip it between 0 and 1 instantly, without typing. (Left-click any field to put the cursor there.)
- In the Name panel, type to insert characters,
Backspace/Deleteto remove (hold to repeat), arrows to move the caret. Ctrl+ an audition key — hear the instrument you're editing at that pitch;Spacere-triggers the last note. Changes are applied and audible live.Ctrl+Insdrops the edited instrument into the selected bank slot;Ctrl+Delclears the selected slot.
Edits never touch your original .RTI files. The header shows MODIFIED
while a working copy has unsaved changes. Ctrl+Z / Ctrl+Y undo / redo your
edits. If you navigate to another instrument with unsaved edits, PokeyForge asks
Keep in bank / Discard / Cancel (click the buttons or press K / D / C)
— "Keep" stores the edit into the bank, where it stays orange until you save the
bank with F2.
To save an edited instrument on its own (not via the bank), press Ctrl+S to
export it as a new .RTI — a Save dialog lets you choose the name and
location. The original file is left untouched.
F4 opens a folder picker so you can point PokeyForge at a different folder of
.RTI files without restarting. The tree, file list, and panels refresh to the
new library, and the choice is remembered for next launch. (Your bank is left
untouched when you switch.)
F7 (or the Analyse menu button) scans every .RTI in the library and:
- Finds duplicates — two instruments are duplicates if their sound
definition is byte-identical, regardless of filename or instrument name.
The first one (alphabetically) is kept; the rest are hidden from the
browse list and tree. Your files are never deleted —
F9shows/hides the duplicates again at any time. - Categorises each instrument (Bass / Lead / Percussion / Noise-FX / Pad /
Other) from its parameters and envelope.
F8toggles the directory pane between the normal folder view and a grouped-by-category view.
The results are cached in analysis.json in the library folder, so the next
time you open that library the categories and de-duplication are restored
automatically. The classification is heuristic — treat the categories as a
helpful rough grouping, not a strict taxonomy.
F5 toggles between PAL (50 Hz, European Atari) and NTSC (60 Hz, US Atari).
This subtly changes the pitch and the speed at which envelopes advance — match
it to the system your music targets. PokeyForge starts in PAL.
F11— toggle fullscreen. The layout scales to fit and stays correct at any size.F1— show or hide the on-screen keybindings. While it's open,F1orEsccloses it.
Close the window (the title-bar close button or Alt+F4). Esc does not
quit — it silences playback so you can stop a long sound without leaving the
app.
Browsing & auditioning
| Key | Action |
|---|---|
a–z, 0–9 |
Play the current instrument at chromatic pitches (low → high) |
[ / ] |
Octave shift down / up |
← / → or ↑ / ↓ |
Previous / next instrument (hold to repeat) |
| Mouse wheel | Move the selection quickly (3 instruments per notch) |
| Click a tree row | Select that instrument (or expand a folder / collapse a category) |
PageUp / PageDown |
Jump back / forward 10 instruments |
Home / End |
First / last instrument |
/ |
Search — filter the list by name (type, Enter keeps it, Esc clears) |
Enter |
Collapse / expand the current file's folder |
Esc |
Silence playback (or close the help overlay) |
Bank
| Key | Action |
|---|---|
| Mouse click | Select a bank slot (filled slot also loads it) |
Tab / Shift+Tab |
Move the bank selection cursor forward / back |
Ctrl + ← / → |
Move the bank cursor by one slot |
Ctrl + ↑ / ↓ |
Move the bank cursor by a row (±8) |
+ (or =) |
Add the current instrument to the next free slot |
- |
Remove the current instrument from the bank |
Ctrl + a–z/0–9 |
Sample (play) the selected bank slot |
Ctrl+Ins |
Copy the current instrument into the selected slot (confirm if occupied) |
Ctrl+Del |
Delete the selected slot (confirm) |
| EDIT button (bank panel) | Toggle bank-edit: when on, Ctrl+C/X/V move slots; when off they play |
Ctrl+C / Ctrl+X / Ctrl+V |
(EDIT on) copy / cut / paste a bank slot (cut + paste = move/reorder) |
Editing (F6 to toggle Edit mode)
| Key | Action |
|---|---|
F6 |
Toggle Edit mode |
Tab / Shift+Tab |
Move between Parameters / Envelope / Note table / Name |
| Arrows | Move the cell cursor (follows the on-screen grid layout) |
0–9, A–F |
Type a value into the cell |
+ / - or Shift+↑ / Shift+↓ |
Nudge the value up / down |
Type / Backspace / Delete |
Edit the name (Name panel; hold to repeat) |
| Left-click a field | Put the edit cursor on that field (enters Edit mode) |
| Right-click a field | Toggle a binary field (AUDCTL flag, type/mode, filter) |
Ctrl+Z / Ctrl+Y |
Undo / redo the last edit |
Ctrl+S |
Export the current instrument as a new .RTI file |
Ctrl + key |
Audition the instrument being edited; Space replays |
Files & display
| Key | Action |
|---|---|
F1 |
Toggle on-screen help |
F2 |
Save the bank (.rmt + .rti folder) via Save dialog |
F3 |
Load a bank (.rmt file or saved bank folder) |
F4 |
Switch to a different instrument library folder |
F5 |
Toggle PAL / NTSC |
F7 |
Analyse: classify instruments + hide duplicates (writes analysis.json) |
F8 |
Toggle folder view / group-by-category |
F9 |
Show / hide duplicate instruments |
F11 |
Toggle fullscreen |
| About button | Show the about / credits popup (any key or click closes it) |
| Drag & drop | Drop a folder (open as library) or a .RTI (open its folder + select) onto the window |
| Close window | Quit |
- 64-bit Windows.
- The program ships with everything it needs next to the executable: the SDL3
library, the POKEY and 6502 emulation libraries, and the RMT tracker driver.
Don't separate
PokeyForge.exefrom those files. - On first run PokeyForge writes a small
pokeyforge.jsonnext to the executable to remember your last library, last bank, and last instrument. Deleting it just resets those memories; it's safe to remove. - Running Analyse (
F7) writesanalysis.jsoninto the library folder (the categories + duplicate list for that folder). It's also safe to delete; it just gets regenerated next time you analyse.
Toolchain: Visual Studio 2022 (v143 toolset), x64, C++17. SDL3 (3.4.8) is
vendored in the repo under lib/, so there's nothing extra to install.
MSBuild PokeyForge.sln /p:Configuration=Release /p:Platform=x64
(or open PokeyForge.sln in the IDE and build). The produced executable is
PokeyForge.exe.
Output lands in build\Release\, and a post-build step copies the runtime
assets (SDL3.dll, sa_pokey.dll, sa_c6502.dll, rmt_driver_v2.obx) next to
the exe so it runs in place. See tech.md for the full architecture
and internals.
- Done: browse, play, inspect, and build banks; save banks as
.RMT+.RTIfiles; reload banks; switch libraries; remember your place between sessions; in-place editing of parameters, envelope, note table, and name with live audition and undo/redo; bank slot sampling and Ctrl bank operations; search, auto-categorisation, and duplicate detection. - Possible future work: stereo (8-channel) playback, multi-voice/chord audition, and selectable RMT driver versions.
PokeyForge reuses the audio core from Raster Music Tracker (by Raster / Radek
Štěrba, with later work by VinsCool and others) and the standalone POKEY and
6502 emulators (sa_pokey.dll, sa_c6502.dll) from Avery Lee's Altirra. PokeyForge
itself is an independent front-end built on top of those components.
The PokeyForge application code (everything under src/) is released under the
MIT License — see LICENSE.
Copyright © 2026 RetroCoder.
The bundled runtime components are not covered by that license and remain under their respective authors' terms:
- SDL3 — zlib license (Sam Lantinga / the SDL contributors).
- POKEY & 6502 cores (
sa_pokey.dll,sa_c6502.dll) and the RMT tracker driver (rmt_driver_v2.obx) originate from Altirra and Raster Music Tracker respectively; consult those projects for their licensing. They are redistributed here for convenience as PokeyForge depends on them at runtime.
If you intend to redistribute PokeyForge, review the upstream licenses for these third-party components.