From ec1e640dfd70220abe16e065a84bb7bee8dbe1e8 Mon Sep 17 00:00:00 2001
From: marcobaye <marcobaye@4df02467-bbd4-4a76-a152-e7ce94205b78>
Date: Tue, 14 Sep 2021 13:32:00 +0000
Subject: [PATCH] fixed comments in vdc library file

git-svn-id: https://svn.code.sf.net/p/acme-crossass/code-0/trunk@321 4df02467-bbd4-4a76-a152-e7ce94205b78
---
 ACME_Lib/cbm/c128/vdc.a | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/ACME_Lib/cbm/c128/vdc.a b/ACME_Lib/cbm/c128/vdc.a
index b0741af..9b550de 100644
--- a/ACME_Lib/cbm/c128/vdc.a
+++ b/ACME_Lib/cbm/c128/vdc.a
@@ -173,8 +173,8 @@ vdcr_display_lo		= $0d	; 0
 vdcr_crsr_hi		= $0e	; 0	RAM address of cursor
 vdcr_crsr_lo		= $0f	; 0
 vdcr_lp_y		= $10	; --	y position of light pen (lines, plus 1)
-vdcr_lp_x		= $11	; --	x position if light pen (characters, plus 8)
-vdcr_ram_hi		= $12	; --	RAM address of register $1f
+vdcr_lp_x		= $11	; --	x position of light pen (characters, plus 8)
+vdcr_ram_hi		= $12	; --	RAM address of register $1f (reading/writing register $1f automatically increments this address)
 vdcr_ram_lo		= $13	; --
 vdcr_attr_hi		= $14	; $08	RAM address of attribute buffer
 vdcr_attr_lo		= $15	; $00
@@ -182,8 +182,8 @@ vdcr_charwidth		= $16	; $78	4b total minus one, 4b displayed minus one
 vdcr_charheight_disp	= $17	; 8	5b displayed, minus one
 vdcr_control_v		= $18	; $20	vertical scroll and much other stuff
 	vdcr_CONTROLV_BLOCKMODE_MASK	= %#.......
-;	vdcr_CONTROLV_BLOCKMODE_WRITE	= %........
-	vdcr_CONTROLV_BLOCKMODE_COPY	= %#.......
+;	vdcr_CONTROLV_BLOCKMODE_WRITE	= %........	; writing to register $1e starts block write
+	vdcr_CONTROLV_BLOCKMODE_COPY	= %#.......	; writing to register $1e starts block copy
 	vdcr_CONTROLV_REVERSESCREEN	= %.#......
 	vdcr_CONTROLV_FLASHFREQ_MASK	= %..#.....
 ;	vdcr_CONTROLV_FLASHFREQ_FAST	= %........
@@ -202,7 +202,7 @@ vdcr_control_h		= $19	; $47 ($40 for vdc version 0)	horizontal scroll and much o
 	vdcr_CONTROLH_PIXELWIDTH_WIDE	= %...#....
 	vdcr_CONTROLH_LEFTSCROLL_MASK	= %....####
 vdcr_color		= $1a	; $f0	4b foreground, 4b background
-	vdcr_COLOR_FOREGROUND_MASK	= %####....	; only used if attributes are off
+	vdcr_COLOR_FOREGROUND_MASK	= %####....	; only used if attributes are off (see bit 6 of reg $19)
 	vdcr_COLOR_BACKGROUND_MASK	= %....####
 vdcr_row_inc		= $1b	; 0	address increment per row
 vdcr_charset		= $1c	; $20	3b charset pointer, 1b RAM type, 4b unused
@@ -212,12 +212,12 @@ vdcr_charset		= $1c	; $20	3b charset pointer, 1b RAM type, 4b unused
 	vdcr_CHARSET_RAMTYPE_64K	= %...#....
 vdcr_underline		= $1d	; 7	5b scanline
 vdcr_cycles		= $1e	; --	number of write- or copy-cycles. 0 means 256.
-vdcr_access		= $1f	; --	RAM content of address r$12/13
-vdcr_source_hi		= $20	; --	RAM address of cycle start
+vdcr_access		= $1f	; --	contents of RAM selected by registers $12/$13
+vdcr_source_hi		= $20	; --	start address for block copy
 vdcr_source_lo		= $21	; --
 vdcr_enable_start	= $22	; 125	column to enable display in
 vdcr_enable_end		= $23	; 100	column to disable display in
-vdcr_dram_refresh	= $24	; 5	RAM refresh rate (lower 4 bits)
+vdcr_dram_refresh	= $24	; 5	RAM refresh cycles per line (lower 4 bits)
 vdcr_sync_polarity	= $25	; --	only in VDC 8568
 	vdcr_HSYNC_POLARITY	= %#.......
 	vdcr_VSYNC_POLARITY	= %.#......