> Why’s the Spectrum’s screen layout different from, say, a C64? The explanation on the page sounds a lot like the 64’s. This was done for some deep hardware r

> Why’s the Spectrum’s screen layout different from, say, a C64? The explanation on the page sounds a lot like the 64’s. This was done for some deep hardware reasons. The DRAM in ZX Spectrum was addressable in pages of 128 bytes (7 bits). So to select the address, the controller had to first select the page and then read the byte. But due to the screen organization, the address of a pixel and the address of its attribute shared the same low 7 bits of the address (out of 14 in total) so that the CPU could address both without having to switch the page.