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The ULA controlled memory access and was able to provide 32K × 8 bits of addressable RAM using 4 × 64K × 1-bit RAM chips ( 4164 ).

Due to needing two accesses to each chip instead of one, and the complications of the video hardware also needing access, reading or writing RAM was much slower than on the BBC Micro.

This meant that although ROM applications ran at the same speed, there was a substantial speed decrease on applications running from RAM.