Battlestar Galactica is known for using "Toaster" as a cybernetic slur, however, I'm curious whether it's been used in that context before, and if so, what's the earliest example of it?
In the Star Trek: The Next Generation episode "The Measure of a Man" 13 February 1989:
Picard and Riker are present to hear the outcome of the research into Data's status)
PHILLIPA: I have completed my research, based on the Acts of Cumberland passed in the early twenty first century. Data is the property of Starfleet. He cannot resign and he cannot refuse to cooperate with Commander Maddox.
PICARD: What if I challenge this ruling?
PHILLIPA: Then I shall be required to hold a hearing.
PICARD: Then I so challenge. Convene your hearing.
PHILLIPA: Captain, that would be exceedingly difficult. This is a new base. I have no staff.
PICARD: But surely, Captain, you have regulations to take care of such an eventuality.
PHILLIPA: There are. I can use serving officers as legal counsel. You as the senior officer would defend.
PICARD: Very good.
PHILLIPA: And the unenviable task of prosecuting this case would fall on you, Commander, as the next most senior officer of the defendant's ship.
RIKER: I can't. I won't. Data's my comrade. We have served together. I not only respect him, I consider him my friend.
PHILLIPA: When people of good conscience have an honest dispute, we must still sometimes resort to this kind of adversarial system.
RIKER: You just want me to prove that Data is a mere machine. I can't do that because I don't believe it. I happen to know better. So I'm neither qualified nor willing. You're going to have to find someone else.
PHILLIPA: Then I will rule summarily based upon my findings. Data is a toaster. Have him report to Commander Maddox immediately for experimental refit.
RIKER: I see. I have no choice but to agree.
This is the first time I remember a robot being called a toaster.
13 February 1989 is before Battlestar Galactica (2004) and after Battlestar Galactica (1978).
I remember "tin cans" being used as a anti Cylon phrase in Battlestar Galactica (1978) but not "toaster".
So as I far as I know "Toaster" was first used as an anti robot slur in either Star Trek: The Next Generation "The Measure of a Man" 13 February 1989 or Battlestar Galactica (1978) if I forgot about a use of it in that series.
Wild Cards: Aces High 1987
Modular Man is often negatively referred to as a 'toaster' by his creator.