76638
The heart of the automation was an 8 x 24 telephone stepping relay which controlled two reel-to-reel tape decks , one twelve inch Ampex machine providing the main program audio and a second RCA seven inch machine providing " fill " music .
 Ampex, RCA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Ampex, RCA