Keyboard Matrix Diagnostic (v3 — row-major fix)
AY R14: $FF
VIA PB: $00
Row: 0
PB3: 0
Green = pressed. Shows real-time 8×8 matrix state.
Convention: keyMatrix[row][col]. D=R1C5, Q=R1C6.
Charset Inspector (from RAM)
Shows characters 32-127 as read from RAM. Empty = ROM not yet copied charset data.
Memory Map
$0000-$00FF Zero Page
$0100-$01FF Stack
$0200-$02FF System Variables
$0300-$030F 6522 VIA I/O
$0400-$97FF User RAM (~37KB)
$9800-$9AFF Charset STD (HIRES)
$9C00-$9EFF Charset ALT (HIRES)
$A000-$BF3F HIRES bitmap
$BF68-$BFE0 HIRES text area
$B400-$B6FF Charset STD (TEXT)
$B800-$BAFF Charset ALT (TEXT)
$BB80-$BFDF TEXT screen (40×28)
$C000-$ECC3 ROM: BASIC routines
$ECC4-$EFFF ROM: OS routines
$F400-$F6FF ROM: Standard Charset
$F700-$F9FF ROM: Alternate Charset
$FA00-$FFFF ROM: OS routines, vectors