Understanding Wavetables

Wavetables in reSIDue are step-sequenced automation tables that control SID registers over time. Each wavetable has:

• 32 Steps: Numbered 0-31 (displayed as rows)
• Control Columns: Exec, Loop for timing control
• Data Columns: Register-specific values (frequency, pulse width, etc.)

Wavetable Types

FREQ (Frequency):

• FrqA: Absolute frequency (16-bit unsigned, 0000-FFFF hex)
• FrqR: Relative frequency change (16-bit signed, -8000 to +7FFF)
• NotA: Absolute MIDI note (16-bit unsigned)
• NotR: Relative note change (16-bit signed)

PULS (Pulse Width):

• PulA: Absolute pulse width (12-bit, 000-FFF hex)
• PulR: Relative pulse width change (16-bit signed)

CTRL (Control Register):

• Va: Control byte (8-bit, 00-FF hex)
• Bits 7-4: Waveform (1=Triangle, 2=Sawtooth, 4=Pulse, 8=Noise)
• Bit 3: Test (usually 0)
• Bit 2: Ring Modulation
• Bit 1: Sync
• Bit 0: Gate

A/D (Attack/Decay):

• Va: Attack/Decay byte (8-bit, 00-FF hex)
• Bits 7-4: Attack rate (0=fastest, F=slowest)
• Bits 3-0: Decay rate (0=fastest, F=slowest)

S/R (Sustain/Release):

• Va: Sustain/Release byte (8-bit, 00-FF hex)
• Bits 7-4: Sustain level (0=lowest, F=highest)
• Bits 3-0: Release rate (0=fastest, F=slowest)

Filter/Vol (Global Filter/Volume):

• FCoA: Filter cutoff absolute (11-bit, 000-7FF hex)
• FCoR: Filter cutoff relative (11-bit signed)
• RF: Resonance/Filter routing (8-bit)
• Bits 7-4: Resonance (0=none, F=maximum)
• Bits 2-0: Voice filter routing (bit 0=Voice1, bit 1=Voice2, bit 2=Voice3)
• MV: Mode/Volume (8-bit)
• Bits 7-4: Filter mode (1=Low Pass, 2=Band Pass, 4=High Pass)
• Bits 3-0: Main volume (0=silent, F=maximum)

Timing Control

EXEC Column (8-bit, 00-FF hex):

• 00: Execute immediately, check LOOP for jump commands
• 01-FF: Wait this many 50Hz cycles before continuing

LOOP Column (8-bit, 00-FF hex):

• 00: Set loop start point to current row
• 01-FF: Loop counter – jump back to loop point this many times

Data Entry

Hexadecimal Input:

• Type hex values directly (case insensitive)
• Automatic uppercase conversion
• No need to delete existing values – just type new ones

Decimal Input (v0.6.21):

• Enter decimal values with explicit + or – prefix
• Examples: “+1000”, “-500”, “+32767”, “-128”
• Automatic conversion to internal integer format
• Values display in hex format as usual

Mixed Input Support:

• With +/- prefix: Parsed as decimal (“+1000” = 1000 decimal)
• Without prefix: Parsed as hexadecimal (“3E8” = 1000 decimal)
• Both methods store identical values internally
• Complete backward compatibility with existing patches

NULL Values:

• Leave fields empty for no change to register
• Display as “–” (8-bit) or “—-” (16-bit)
• Preserves current SID register state

Navigation:

• Arrow Keys: Move between cells
• Tab/Shift+Tab: Move to next/previous cell
• Enter: Move to next row, same column
• Escape: Clear focus