When the ZX80 was released in 1980, it came with a version of BASIC in a 4K ROM chip, known as 4K BASIC. Note this has nothing to do with RAM (the ZX80 has 1K, upgradeable to 16K), it is the size of the ROM chip.
These only come in the version with the grey keys and 8K BASIC keywords.
my Tindie Store for more options.
white ZX81 cased ZX80, now with a choice of keyboard overlays.
My thanks once again to Grant Searle, these were adapted from his ZX81 overlay artwork.
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