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However, there are pin headers P207, P208, P209 and P210 next to the CPU, originally used to connect the memory daughterboard or a test system, that make it easy to add a small custom piggyback board with a decoder and a more modern E(E)PROM. An 8k×8 chip (2764, 2864) is sufficient to hold the 6kB needed for the DF2. As a bonus, this upgrades a DF1 to a DF2 if the missing front panel key is added as well (pads are present on the PCB). The stock ROM chips must be removed prior to installing the piggyback board. | However, there are pin headers P207, P208, P209 and P210 next to the CPU, originally used to connect the memory daughterboard or a test system, that make it easy to add a small custom piggyback board with a decoder and a more modern E(E)PROM. An 8k×8 chip (2764, 2864) is sufficient to hold the 6kB needed for the DF2. As a bonus, this upgrades a DF1 to a DF2 if the missing front panel key is added as well (pads are present on the PCB). The stock ROM chips must be removed prior to installing the piggyback board. | ||
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Tek DF1 DF2 ROM replacement board schematic.png | ROM piggyback board schematic (click to enlarge) | Tek DF1 DF2 ROM replacement board schematic.png | ROM piggyback board schematic (click to enlarge) | ||
Tek DF1 ROM_piggyback.jpg | Prototype | Tek DF1 ROM_piggyback.jpg | Prototype |