1. Overview:

️· Function: These chips (MSM6650 family) are integrated circuits designed for playing back pre-recorded speech phrases. They are essentially programmable sound generators, allowing for playback based on inputs and with some randomization capabilities.
️· Programming: Speech data is pre-recorded and stored within the chip. Editing and loading this data likely requires external tools (AR203 or AR204 are mentioned)
️· Target Applications: Simple voice-box toys, talking cards, simple electronic devices.

2. Chip Variations & Pinouts (Combined & Simplified)

The documentation details three primary versions, each with slight variations.

2.1 MSM6652/53/54/55/56 & MSM6652A/53A/54A/55A/56A/58A (24-Pin Plastic SOP)

️· Key Features: Standard playback functionality, ROM-based speech storage.
️· Pin Descriptions:
- 1 (VDD): Power Supply (0.1uF bypass capacitor recommended)
- 2 (OSC1): Ceramic Oscillator Input / RC Oscillator Input
- 3 (OSC2): Ceramic Oscillator Output / RC Oscillator Output. Leave open when using an external clock.
- 5 (OSC3): RC Oscillator Input (leave open for ceramic oscillators)
- 9-12 (SW0-SW3): Phrase Inputs (capture data after 16ms)
- 13-15 (A0-A2): Phrase Inputs (A0 becomes invalid in random playback)
- 17 (RESET): Reset (active low)
- 22 (XT/CR): Selects between crystal oscillator (XT) or RC oscillator (CR).
- 24 (GND): Ground
- 17 (RESET): Reset.
- 16 (TEST): Test Mode pin.

2.2. MSM66P54-xx & MSM66P56-xx (20-Pin Plastic DIP)

️· Key Differences: These versions have fewer pins and introduce the `VPP` and `PGM` pins.
️· Pin Descriptions:
- All same as the 24-pin except for the following:
- 1 (VPP): Power supply used for OTP ROM writing. Leave open or set HIGH during playback.
- 7 (PGM): Interface pin for voice analysis/editing tool (AR203 or AR204). Set LOW or leave open during playback.
- Missing Pins: Pins 18, 19 and 24 are not used.

2.3. MSM6652/53/54/55/56 & MSM6652A/53A/54A/55A/56A/58A (24-Pin Plastic SOP)
️· Key Features: Standard playback functionality, ROM-based speech storage.
️· Pin Descriptions: All same as the 20-pin except for the following:
- Missing pins: 1, 7, 18, 19, and 24 are not used.


3. Important Features & Functionality

️· Random Playback: Triggered by the `RND` pin. Generates random playback addresses. `A0` input is invalid during this mode.
️· Phrase Input (SW0-SW3 & A0-A2): Phrase inputs capture data and initiate playback.
️· Oscillator Selection (XT/CR): `XT/CR` pin selects between using an external crystal oscillator or using an internal RC oscillator.
️· OTP ROM: Some variants (P54 and P56) include an OTP (One-Time Programmable) ROM, requiring a separate programming tool.