C=Key Keyboard interface
Introduction
C=Key bridges the gap between Commodore and PC keyboard operation!
Depending on configuration, C=Key offers VIC-20, C64, C64C, SX64, C128, C128D, and C128DCR owners the ability to either use their CBM keyboard with a PS/2 supported PC, or utilize a PS/2 keyboard on their Commodore machine. In either usage, multiple keyboard mappings are supported, to handle keyboard differences and application preferences. No drivers or programming are required for operation.
Options
C=Key can be purchased in the following configurations:
- PCB Only: Bare circuit board
- PCB + uC: PCB and programmed Atmel ATMEGA162, used for connecting CBM KB to PC (includes uC Crystal and trimming capacitors)
- PCB + uC + Crosspoint Switch: Allows either configuration
- Preconfigured kits for specific CBM models.
Additional options include:
- dual joystick connectors can be added, to allow CBM joystick operation on the PC.
- Any kit can be ordered pre-assembled (please allow additional handling time)
Requirements
- A PS/2 compatible keyboard (USB keyboards with PS/2 converters may not work) with a Mini-DIN6 plug.
- One of the following machines:
- VIC-20, C64, C64C
- SX64
- C128
- C128D/C128DCR
- For the SX64/C128D/C128DCR operation with a PS/2 keyboard, a DB25M to DB25M cable is also required.
Purchase
C=Key models can be purchased at the RETRO Innovations Online Store.
Image Gallery
Technical Details
C=Key consists of an Atmel ATMEGA162 microcontroller in DIP format and an optional Mitel/Zarlink MT8812 crosspoint switch. In “host” mode, the system reads data from the PS/2 keyboard and emulates the Commodore switch matrix with the crosspoint switch. In “device” mode, the system scans the Commodore keyboard matrix 60 times a second, converting keypresses into PS/2 compliant scan codes. GPLv2 licensed C firmware source code can be modified to support nearly any matrix-style keyboard configuration.
Firmware features include:
- Multiple key rollover support
- Configurable keyboard matrix scanner supports 1×1 to 16×8 matrices (hardware supports a maximum of 12×8 matrices)
- Single IC solution (for matrix keyboard to PC configuration)
- Key repeat functionality supported and PS/2 keyboard compliant
The PCB features include:
- A single PCB for VIC/64/128/SX64
- Support for dual joysticks for emulator use.
- Through hole design makes “do-it-yourself” construction easy.
Support
Bill of Materials
| Part | Description |
|---|---|
| X1 | Mini-DIN6 PS/2 Connector |
| R1 | 10K 1/8W resistor |
| IC1 | Atmel ATMEGA48/88/128/328 uC |
| C1,C2 | 18pF ceramic capacitor |
| C3 | .1uF ceramic capacitor |
| Q1 | 8MHz crystal |
| SV1 | DIP24 IC header |
| SV2 | 2×12 breakaway header |
| CONFIG | 1×2 .1″ breakaway header |
Assembly Details
Operation
- C
Configuration
OLD STUFF
View some pictures or download the code and schematic
- Any kit can be ordered pre-assembled (please allow additional handling time)