Homebrew:RAM test

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Used to test the Multi-Cart on board RAM which is placed on the same address location as the SABA 20 Chess game. Reason for this is that this cart was used as a donor for the early Multi-Carts and a test was needed to check that it was OK before sent out to a happy gamer.

Program is run with a nice colorful interface, every memory bit (2048 of them) of the cart RAM is represented by a pixel in the large rectangle in the middle. When tested it's blue, when green it was tested OK and if red it was bad. A full test takes a few minutes because the graphics updated for each bit, a blind test would be a lot faster.

Latest version makes a quick test writing and reading back %10101010 and %01010101 before turning all four RAM capsules green to indicate that these are OK, then a full write and read test is preformed from %00000000 to %11111111 and if there's an error the corresponding RAM capsule is marked in red as well as the bit. For later carts a single 6116 SRAM is used instead so if there's any error at all the whole capsule needs to be replaced.

However, after building over 100 carts there has never been any errors in the cart RAM.