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Variables.md

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Variables

Constants

address size value description
c86f 1 $0d CRTC R10 default configuration

Default bank

address size name bits description
ffb7 - [3:0] FDC descriptor: Bit flags of already accessed floppy drives
ffb8 - [1:0] FDC descriptor: Bytes per sector "factor" (bps = 0x80 << f) [^TODO2]
ffb9 - [2] FDC descriptor: Head number (0 or 1)
- [1:0] FDC descriptor: Addressed drive (0 up to 3)
ffba - [7:4] FDC descriptor: operation command [^TODO]
- [3:0] FDC descriptor: TBD
ffbb 1 - FDC descriptor: sector number
ffbc 1 - FDC descriptor: track number
ffbd 2 - FDC descriptor: r/w buffer pointer
ffbf 1 - FDC descriptor: max retry for rwfs operations
....
ffc7 1 display-related stuff
ffc8 1 display-related stuff
ffc9 1 display-related stuff
ffca 1 current_column display column where the cursor is positioned
ffcb 1 current_row display row where the cursor is positioned
ffcc
ffcd 1 number of rows contains configured number of displayed rows (default: 24)
ffce 1 column
ffcf 1 set to 0, then never changed?
ffd0 1 something which has to do with display columns (see $ffcb and $ffca too)
ffd1 magenta [3,4] current character text attribute
ffd2
ffd3 1 crtc_r10_mem [5:6] CRTC R10 (cursor start raster)
ffd4 2 IX - CRTC memory start address
ffd6 2 IY - CRTC memory pointer (eg. video memory address - $d000)
ffd7
ffd8 1 escaped_char ? remember current escaping char during a putchar()
" Values: $00 = no ongoing escaping, $01 = ongoing escape, any other: current char to be escaped?
ffd9 1 blues index of array at $ffda ?
ffda 3(+) cyan
....