Routines
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E801: Clear the screen
Used by the routines at C881, CA5B, DB63, DCF6, E62F and F2F4.
E801 LD HL,$4000 Start copying from the top of the screen, and for the length of it.
E804 LD BC,$1800
E807 LD (HL),L Set the first byte to 0.
E808 LD D,H Start copying to the second byte in the screen.
E809 LD E,$01
E80B LDIR Do the copy, which will fill the screen with 0.
At this point, HL is pointing to the attributes.
E80D LD A,$45 Use bright cyan on black.
E80F LD (HL),A Set the first cell.
E810 LD BC,$02FF Fill the rest of the attributes.
E813 LDIR
Set the border to black.
E815 LD A,($E800) Get the last read to port FE. (E800)
E818 AND $F8 Ignore the border bits, it is always black.
E81A OUT ($FE),A Set the port values.
E81C LD ($E800),A Remember this for later.
E81F RET Return.
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