TVout and old composite monitor

[Kamarad22]

Hello,

I successfully have TVout displaying on a modern NTSC composite monitor.

I am however trying to adapt it to and old TRS80 composite (NTSC?) CRT which was sold in USA in the eighties. The problem is I cannot figure out what changes needs to be made in the values of the video_properties.h file (or other files?) to adapt it to the kind of images accepted by this old cathodic CRT. All I get is a garbled image scrolling on screen on which you can only recognize some letters of the test display I prepared with TVout.

Here are the specs of the signal as per the TRS80 service manual:

Horizontal retrace (uSec): 8.2
Vertical retrace (uSec): 700
Scanning horizontal Frequency : 15840 Hz
Scanning vertical Frequency : 47-63 Hz
Resolution at center: 800 lines (Corner 680)
Display capacity: 24 rows X 80 characters
The display is also capable of displaying640X240 or 512X192 when connected to the appropriate "advanced" graphic card.

I understand this CRT had been probably made specifically for the TRS80, which is based on a Z80 processor equipped with 16 K Ram, the video video being handled by a CRTC 8064 controller which generate the necessary Vsync, Hsync and DISPEN (?) signals. Of course, whith TVout I bypass this controller and connect directly to the CRT circuitry. When connected to the original Z80 TRS80 motherboard, the display is working properly.

Which modification should I do to the TVout software in order to adapt it to this monitor, and, in general, how do you calculate the values to be fed to TVout considering the original CRT specifications?

Thanks a lot for any advice!

Model 4P Service Manual 1984.pdf