Re: VDU programming question

[oscarv <vermeul...@gmail.com>]

Hi,

If you only printed on the top line, and saw garbled output there, then maybe this is it:

Regards,

Oscar.


Sometimes, the top line of the screen is 
invisible or garbled. If this is the case, edit VDU.ASM as follows. The 
change just causes the VSYNC signal to be generated two lines earlier, 
shifting the screen down:​

​

Change from:
  VDU_INIT6845:
  .DB 07Fh,50h, 60h, 0Ch, 1Eh, 02h, 18h, 1Ch, 78h, 09h, 60h, 09h, 00h, 00h, 00h, 00h

Change into:
  VDU_INIT6845:
  .DB 07Fh,50h, 60h, 0Ch, 1Eh, 02h, 18h, 1Ah, 78h, 09h, 60h, 09h, 00h, 00h, 00h, 00h