UNIDENTIFIED
TURBO MAIN BOARD (426A)
| Processor | 8088 | 
| Processor Speed | 4.77/8MHz | 
| Chip Set | Unidentified | 
| Video Chip Set | None | 
| Maximum Onboard Memory | 640KB | 
| Maximum Video Memory | None | 
| Cache | None | 
| BIOS | Unidentified | 
| Dimensions | 330mm x 218mm | 
| I/O Options | None | 
| NPU Options | 8087 | 
 
| CONNECTIONS | |||
| Purpose | Location | Purpose | Location | 
| Turbo switch (to turbo switch button) | JP5 | Power LED | JP9 pins 3 & 4 | 
| Turbo LED | JP9 pins 1 & 2 | Speaker | P4 | 
| USER CONFIGURABLE SETTINGS | |||
| Function | Label | Position | |
| » | Factory configured - do not alter | JP1 | Unidentified | 
| Turbo enabled | JP6 | Closed | |
| Turbo disabled | JP6 | Open | |
| Turbo enabled (CTRL, ALT, +) | JP7 | Closed | |
| Turbo disabled (CTRL, ALT, -) | JP7 | Open | |
| Keyboard lock disabled | JP8 | Closed | |
| Keyboard lock enabled | JP8 | Open | |
| » | Factory configured - do not alter | SW1/1 | Off | 
| NPU not installed | SW1/2 | On | |
| NPU installed | SW1/2 | Off | |
| Note: JP6 is for turbo selectable through hardware. JP7 is for turbo selectable through software. Both jumpers cannot be closed at the same time. | |||
| DRAM CONFIGURATION | ||||
| Size | Bank 0 | Bank 1 | Bank 2 | Bank 3 | 
| 256KB (A) | (9) 4164 | (9) 4164 | (9) 4164 | (9) 4164 | 
| 256KB (B) | (9) 41256 | None | None | None | 
| 512KB | (9) 41256 | (9) 41256 | None | None | 
| 640KB | (9) 41256 | (9) 41256 | (9) 4164 | (9) 4164 | 
| Note: The location of banks 0, 1, 2, & 3 are unidentified. | ||||
| DRAM JUMPER CONFIGURATION | ||
| Size | JP3 | JP4 | 
| 256KB (A) | Pins 1 & 3, 5 & 7 closed | Pins 2 & 4 closed | 
| 256KB (B) | Pins 2 & 4, 6 & 8 closed | Pins 1 & 3 closed | 
| 512KB | Pins 2 & 4, 6 & 8 closed | Pins 1 & 3 closed | 
| 640KB | Pins 2 & 4, 6 & 8 closed | Pins 1 & 3 closed | 
| DRAM SWITCH CONFIGURATION | ||
| Size | SW1/3 | SW1/4 | 
| 128KB | Off | On | 
| 192KB | On | Off | 
| 256KB | Off | Off | 
| FLOPPY DRIVE SELECTION | ||
| Drives installed | SW1/7 | SW1/8 | 
| 1 | On | On | 
| 2 | Off | On | 
| 3 | On | Off | 
| 4 | Off | Off | 
| MONITOR SELECTION | ||
| Type | SW1/5 | SW1/6 | 
| None | On | On | 
| Color (40 x 20) | Off | On | 
| Color (80 x 25) | On | Off | 
| Monochrome | Off | Off |