ты английский знаешь или перевести ?
The I register is used along with the R register by the Z80 for automatic memory refreshing. Setting the I register to a value between $40 and $7F
causes memory refreshes to occur to the lower 16K RAM. This RAM is contended with the ULA which uses it for the generation of the video display.
The memory refreshes get interpreted by the ULA as the CPU requesting to access the lower 16K RAM bank very rapidly and very often. The ULA is not
able to handle reads at such a high frequency, with the consequence that it fails to fetch and output the next screen byte. Instead it uses re-uses
the byte previously read. This causes a visible corruption to the video display output, often referred to a 'snow', although no actual corruption
occurs to the video display RAM. This also happens when the I register is set to a value between $C0 and $FF when a contended RAM bank is paged in
and, unlike the Spectrum 16K/48K, can lead to a machine crash.
какая версия у тебя работает мне остаётся только догадываться.
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