LK1,LK2,LK3 connect to PPI Port B, Bit1-3. The links select the manufacturer name (which is displayed by the BIOS in the power-up message). These LKs exist on all CPC mainboards (in CPC Plus/GX4000 schematics they are named LK101,LK102,LK103). By default, LK1-LK3 are not installed (Amstrad). Other combinations are LK2 installed in german Schneider models, and LK1+LK2 in australian Awa models.
| Bit 3 (LK3) | Bit 2 (LK2) | Bit 1 (LK1) | Distributor Name |
| 0 | 0 | 0 | Isp |
| 0 | 0 | 1 | Triumph |
| 0 | 1 | 0 | Saisho |
| 0 | 1 | 1 | Solavox |
| 1 | 0 | 0 | Awa (australian CPCs) |
| 1 | 0 | 1 | Schneider (german CPCs) |
| 1 | 1 | 0 | Orion |
| 1 | 1 | 1 | Amstrad (default) |
Note: "0" means LK installed.