From 73ae95bd1c11ccfca9f98d6941ee2600d901c033 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stephan=20M=C3=BChlstrasser?= Date: Mon, 23 Feb 2015 19:06:22 +0100 Subject: [PATCH 1/2] Clear bottom line when scrolling. Fix provided by Jeff Tranter. --- libsrc/osic1p/cputc.s | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/libsrc/osic1p/cputc.s b/libsrc/osic1p/cputc.s index 47969df15..058964573 100644 --- a/libsrc/osic1p/cputc.s +++ b/libsrc/osic1p/cputc.s @@ -58,6 +58,12 @@ scroll: lda SCRNBASE+$00A5,x sta SCRNBASE+$0285,x inx bne scroll +bottom: + lda #' ' ; Clear bottom line of screen + sta SCRNBASE+$0385,x + inx + cpx #SCR_LINELEN+1 + bne bottom plot: ldy CURS_Y lda ScrLo,y From 83f16425c9d2dd2d84b4f6932826538e8b7bd01a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stephan=20M=C3=BChlstrasser?= Date: Mon, 23 Feb 2015 19:17:27 +0100 Subject: [PATCH 2/2] Loading A once before the loop is sufficient. --- libsrc/osic1p/cputc.s | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/libsrc/osic1p/cputc.s b/libsrc/osic1p/cputc.s index 058964573..4e16e92df 100644 --- a/libsrc/osic1p/cputc.s +++ b/libsrc/osic1p/cputc.s @@ -58,8 +58,9 @@ scroll: lda SCRNBASE+$00A5,x sta SCRNBASE+$0285,x inx bne scroll -bottom: + lda #' ' ; Clear bottom line of screen +bottom: sta SCRNBASE+$0385,x inx cpx #SCR_LINELEN+1