A deep dive into restoring and repurposing the 1985 Scriptovision Super Micro Script video titler into a functional home computer using Motorola 6800-series hardware, including ROM decryption, hardware fixes, and custom firmware development.
The Canadian Contender
Canadian tech history includes obscure gems like the Scriptovision Super Micro Script, a 1985 video titler designed in Montréal. This standalone character generator featured:
- Motorola 68B02 CPU @ 0.89MHz
- Motorola 6847 Video Display Generator (VDG)
- 4K RAM with battery backup
- Built-in genlock for video overlays
- 32×16 text and 64×32 block graphics in 8 colors
Unlike broadcast-grade Chyron systems, this $500 (~$1500 today) unit targeted prosumers. Its architecture shared striking similarities with contemporaneous home computers like the Tandy MC-10 and APF Imagination Machine, using nearly identical chipsets.
Hardware Hurdles
Initial restoration faced multiple challenges:
- Failed Video Output: Distorted sync required bypassing the original MC1372 video modulator with a Tandy Color Computer-compatible composite mod board.
- Genlock Issues: Unstable overlays were stabilized by adjusting variable resistors and capacitors in the signal path.
- Encrypted ROMs: Dumped EPROMs appeared as gibberish due to intentional address/data line swizzling to deter cloning. A Perl script reversed the scrambling, revealing operational code.
Memory Constraints and Banking
With only 4K RAM banked in 512-byte pages shared with the VDG, programming required precise timing:
- Code execution limited to ~440 CPU cycles during vertical blanking intervals
- SMSBUG firmware introduced virtual memory management:
- S-bank: Active display page
- U-bank: Execution context
- Helper routines managed bank switching during VBL to prevent display corruption
Serial Port Hack
A bit-banged RS-232 interface added using two test clips:
- Hardware: Row 0 input repurposed as RX, soldered to 74LS244 buffer
- Protocol: 19.2kbps 8-N-1, cycle-counted for 894.886kHz CPU clock
- Utility: Enabled loading programs via checksummed binaries (514-byte packets)
Emulation and Custom Development
The fully documented system inspired a MAME driver with unique features:
- Accurate VDG palette calibration
- Keyboard matrix emulation
- TCP socket support for "bitbanger" serial transfers Sample programs demonstrate capabilities:
- SMSBUG: Interactive monitor with memory editing
- Rock Paper Scissors: VM-based game
- Animated demos: Color bars and scrolling text overlays
Technical Legacy
Post-restoration, the Super Micro Script rivals period home computers:
| Feature | SMS | Tandy MC-10 |
|---|---|---|
| CPU | 68B02 | 6803 |
| Clock | 0.89MHz | 0.89MHz |
| Video | MC6847 | MC6847 |
| Unique Feature | Genlock | RS-232 |
Build Recommendations
For enthusiasts:
- Source units on eBay ($50-$150 non-working)
- Replace ROMs with SMSBUG firmware using flash adapters
- Add serial port with TTL-UART adapter
- Develop using MAME driver for rapid testing
The Super Micro Script exemplifies how specialized hardware can transcend its original purpose—proving even a video titler can become a capable 6800-based home computer.
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