On Sun, 21 Sep 1997 02:36:05 -0400 Steve Smith writes: >In a message dated 20/09/97 23:03:36, you write: > ><< > If you're only seeing the left 8 characters on the display it is >likely > the x16 type. There is no way to test with software what kind it is. > >> >There Is, send a char to RAM location 0 and the next char to RAM >location >D'40' this is the start of the second 8 chars on a 16 x 1 with only >one chip >if the char does not appear then it must be a proper one. Of course this is a test, but it isn't purely software since it requires the user to observe the screen. What I was talking about is writing software that will adapt to use either type without needing the user to set anytihing. I shouldn't have writtne "no" because I can think of a few ways to do that but haven't tried them. The first way would be to set the display in x16 (2-line) mode and copy data for the last 8 characters to both places in RAM. This won't work on an 11-row, 2-chip display because the top parts of the second line characters will appear in the unused bottom 3 pixels of the first half of the line. Also the contrast won't be as good as could be obtained using a 2-chip display in x8 or x11 mode. The old Hitachi book I have says x16 units use a 160 KHz clock and x8/11 ones a 250 KHz clock. This makes the worst-case execution time shorter on the latter displays. If the connection allows reading the busy bit, software could determine the time a command takes and guess at the HD44780 clock speed, which may be related to the type of display. > >Cheers Steve..... >