IFNE   VDGDEFS-1
VDGDEFS  set    1

********************************************************************
* VDGDefs - VDG Interface Definititions
*
* $Id$
*
* Edt/Rev  YYYY/MM/DD  Modified by
* Comment
* ------------------------------------------------------------------
*          1991/05/07  Alan DeKok
* Wrote original from VDGint source.


         nam    VDGDefs
         ttl    VDG Interface Definitions


         pag
* Notes:
*
* All offsets from 'U' (address of device memory area)
* (see p. 6-9, technical reference: U=start of driver data memory
* NOTE: There is LOTS of stuff which is only used once, and some which
* is not needed.  Here's a list of the un-needed, and un-used (other than
* once)
*
* It would probably be benificial to patch VDGint to fix these problems,
* unless anyone else has ideas as to why VDGint is doing things this way.
*
* Un-needed
* VD.EPlt1  - (2) set to VD.NChar, and then read only
* VD.EPlt2  - (2) set to same as VD.EPlt1, and then unused
* VD.Chr1   - (1) set to same as VD.CChar, and then unused
* VD.PlFlg  - (1) initialized to $08, and unused
*
* Un-used
*
* $1D       - (1) end of SCF memory requirements
* VD.Strt1  - (2) CLRed, and then read (LDD) - left as $0000
* $24-$2B   - (8)
* $33-$34   - (2)
* $7E-$FF   - (130)
*
* Total of 22 (150 in whole page) bytes unneeded or unused.

         org   $1E
VD.Start rmb   1  start of VD.XXXX data: number of VDG screens in use
VD.Strt1 rmb   2  (2) and another start
VD.Caps  rmb   2  caps lock info: $00=lower $FF=upper
VD.DFlag rmb   1  0=current screen is valid, $01-$FF = update video
* $24-$2B unused
         rmb   8
VD.NGChr rmb   1  number of additional characters to get
VD.RTAdd rmb   2  (2) return address after getting characters
VD.EPlt1 rmb   2  (2) pointer to where to put next character
VD.EPlt2 rmb   2  (2) as above.
* $33-$34 unused
         rmb   2
VD.CFlag rmb   1  true lowercase flag $10=true, $00=false
VD.CFlg1 rmb   1  VDG display code values
VD.DGBuf rmb   1  number of currently displayed buffer
VD.ScrnA rmb   2  (2) screen start address in system memory
VD.ScrnE rmb   2  (2) address of end of screen
VD.CrsrA rmb   1  (2) cursor address
VD.CrsAL rmb   1  cursor address low
VD.CChar rmb   1  value of character under cursor
VD.Mode  rmb   1  mode: 0=256x192 x2, 1=128x192 x4
VD.Chr1  rmb   1  same as under cursor character
VD.CColr rmb   1  cursor color
VD.Col   rmb   1  number of columns for this screen
VD.Row   rmb   1  number of rows
VD.TFlg1 rmb   1  see WRITE ($0E)
VD.Alpha rmb   1  0 when in alpha mode
VD.Rdy   rmb   1  device ready (see SS.DStat 0=not ready)
VD.SBAdd rmb   2  (2) address of block screen is in
VD.Blk   rmb   1  Block number of screen
VD.GBuff rmb   1  allocation for graphics buffers (block#)
VD.AGBuf rmb   2  (2) additional graphics buffer
VD.HiRes rmb   1  hi-res screen table (block value)
VD.NBlk  rmb   1  number of blocks in this screen
VD.SType rmb   1  screen type 0-4
VD.HR2   rmb   3  (3) for screen number 2
VD.HR3   rmb   3  (3) for screen 3 (same 3 bytes as above)
VD.FFMem rmb   2  (2) bottom of stack for flood fill
VD.FFSPt rmb   2  (2) flood fill stack pointer
VD.FFSTp rmb   2  (2) flood fill stack top pointer
VD.FF6   rmb   1   flood fill flag
VD.MTabl rmb   2  (2) address of mask table for pixels in byte
VD.PixBt rmb   1  bit mask for modes (0=$07, 1=$03 )#pixels/byte
VD.GCrsX rmb   1  graphics cursor X value
VD.GCrsY rmb   1  graphics cursor Y
VD.Msk1  rmb   1  mask byte 1
VD.Msk2  rmb   1  mask byte 2 (00,55,AA,FF)
VD.MCol  rmb   1  color? (C003,8001)
VD.MCol2 rmb   1  color
VD.PMask rmb   1  pixel mask for colors (i.e. $55, $CC etc)
VD.FF1   rmb   1  data for flood fill
VD.FF2   rmb   1  data for flood fill
VD.FFMsk rmb   1  flood fill mask
VD.FFFlg rmb   1  flood fill flag
VD.Palet rmb   16 (16) current palette values
VD.PlFlg rmb   1  initialized to $08 by L00DB, and then unused!
VD.NChar rmb   1  character to process
VD.NChr2 rmb   1  and the next one

* and RMB until we get 256 bytes reserved

         ENDC