Chapter 4 System Register

The functions of the system registers are as follows:

●System register list

TV mode selection TVMR

Address: 100000H Write only (word)

Function: Specify TV display mode

Update period: PTM as needed, VBE in the field

Frame buffer switching mode FBCR

Address: 100002H Write only (word)

Function: Control frame buffer switching and double-dense interlacing

Update timing: For FCM and FMT, each field, for others, frame buffer switching timing

Plot trigger PTMR

Address: 100004H Write only (word)

Function: Controls drawing start

Update timing: 01B write at any time, 00B and 10B write at frame buffer switching timing

Erase write data EWDR

Address: 100006H Write only (word)

Function: Specifies frame buffer fill data when erasing and writing.

Update timing: Frame buffer switching timing

Erase write upper left coordinate EWLR

Address: 100008H Write only (word)

Function: Specifies the upper left coordinates of the fill area of the frame buffer when writing an erase.

Update timing: Frame buffer switching timing

Erase write lower right coordinate EWRR

Address: 10000AH write only (word)

Function: Specifies the lower right coordinates of the fill area of the frame buffer when writing an erase.

Update timing: Frame buffer switching timing

Forced termination of drawing ENDR

Address: 10000CH write only (word)

Function: Force drawing to end

Update period: Any time

Transfer end status EDSR

Address: 100010H Read only (word)

Function: Displays the end bit fetch status of the current and previous frame.

Update time:-

Processing suspension table address LOPR

Address: 100012H Read only (word)

Function: Display final processing command table address of previous frame

Update time:-

Current processing table address COPR

Address: 100014H Read only (word)

Function: Display of command table address currently being processed

Update time:-

Mode state MODR

Address: 100016H Read only (word)

Function: Displays the set value to the write-only register

Update time:-

●Timing at which system register setting values change

The timing at which the system register setting value becomes valid is as follows.

• Something that changes immediately
  Plot trigger mode (when writing PTM, 01B)
  TV mode selection (TVM)

  Things that change every field (1/60 seconds)

  Frame buffer switching mode (FCM)

  Frame buffer switching trigger (FCT)

  What changes when switching frame buffers

  Plot trigger mode (when writing PTM, 00B or 10B)

  Even/odd coordinate selection bit (EOS)

  Double dense interlacing enabled (DIE)

  Double dense interlaced drawing line (DIL)

  Erase write data

  Erase write coordinates (top left, bottom right)

  What changes after 1 line is displayed after V blank IN interrupt

  V blank erase write permission (VBE)