Testing and troubleshooting the RAM module. In this video we check out the RAM module, fix an issue, and make a small modification so RAM writes are triggered on the rising edge of the clock.
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You can get all the components used in this video from any online electronic components distributor (Jameco, Digikey, Mouser, etc). See https://eater.net/bbcpu8-ram for more.
Complete parts list (everything in the RAM module):
- 2x 74LS189 (64-bit random access memory)
- 2x 74LS04 (Hex inverter)
- 1x 74LS173 (4-bit D-type register)
- 4x 74LS157 (Quad 2-to-1 line data selector)
- 1x 74LS245 (Octal bus transceiver)
- 1x 74LS00 (Quad NAND gate)
- 14x LEDs (9 red, 4 yellow, 1 green)
- 3x 1KΩ resistors
- 1x 0.01µF capacitor
- 22 gauge wire
- 5 volt power source (e.g., a USB phone charger)