MySQL Forums :: Newbie :: Index Exceeding Max Length??????

Does anyone know why the following code generates the following error?

CREATE TABLE test1
(
test text(256) NOT NULL,
PRIMARY KEY (test(256))
);

CREATE TABLE test2
(
id int NOT NULL,
test1 text(256) NOT NULL,
test2 text(256) NOT NULL,
PRIMARY KEY (id),
FOREIGN KEY (test1(256)) REFERENCES test1 (test)
);

CREATE UNIQUE INDEX test4_index ON test5
(
test1(256),test2(256)
);

#1071 - Specified key was too long; max key length is 1000 bytes

I thought 256+256=512