So I recently got my first IIGS, but I am having no luck finding the monitor for it. I really wanted a CRT on it but none of the Macintosh monitors are compatible.
Along comes RGBtoHDMI https://github.com/hoglet67/RGBtoHDMI
This can take the Digital RGB signals from the IIGS DAC resistor networks and make a clean HDMI signal.
THE RGB signals are located on the DACs
I then fed the wires out to the RGBtoHDMI
So the RGBtoHDMI is based on a CPLD and Raspberry PI. The PI always had definable video output. Meaning you can set your refresh rate and resolution to what you want and the PI will work with that. This also applies to HDMI>VGA converters so ..
Raspberry PI with HDMItoVGA connected to a fixed frequency Apple Monitor the M1212.
Here are the timings required in the config.txt of the Raspberry Pi
## 640x480 @ 67Hz
hdmi_group=2
hdmi_mode=87
hdmi_timings=640 0 64 64 96 480 0 3 3 39 0 0 0 67 0 30240000 1
Because the M1212 is composite sync we need to convert H + V sync to C-Sync.
6
BC548 680R
HSync ------------- ---------/\/\------o--------- CSync on Green
\ /!
\ /
---------
!
!
1k !
VSync ----/\/\----------
The Result is this:
And because the monochrome Apple 12" has the same timings this is also possible.
Along comes RGBtoHDMI https://github.com/hoglet67/RGBtoHDMI
This can take the Digital RGB signals from the IIGS DAC resistor networks and make a clean HDMI signal.
THE RGB signals are located on the DACs
Apple IIGS (12 bit RGB TTL)
12 Bit Extender 16 way IDC | Motherboard | Notes |
---|---|---|
Pin 1 green0 | H3 Pin 5 | |
Pin 2 red0 | H4 Pin 5 | |
Pin 3 blue0 | H2 Pin 5 | |
Pin 4 green1 | H3 Pin 4 | |
Pin 5 red1 | H4 Pin 4 | |
Pin 6 blue1 | H2 Pin 4 | |
Pin 7 GND | H3 Pin 7 | |
Pin 8 green2 | H3 Pin 3 | |
Pin 9 red2 | H4 Pin 3 | |
Pin 10 blue2 | H2 Pin 3 | |
Pin 11 RED3 | H4 Pin 2 | |
Pin 12 HSYNC | H1 Pin 3 | |
Pin 13 GREEN3 | H3 Pin 2 | |
Pin 14 VSYNC | UF3 Pin 2 (74F86) | Flip 6 Also available on VGC Pin 49 and TP24 |
Pin 15 BLUE3 | H2 Pin 2 | |
Pin 16 +5V | H1 Pin 10 | Leave unconnected if powering Pi externally |
I then fed the wires out to the RGBtoHDMI
So the RGBtoHDMI is based on a CPLD and Raspberry PI. The PI always had definable video output. Meaning you can set your refresh rate and resolution to what you want and the PI will work with that. This also applies to HDMI>VGA converters so ..
Raspberry PI with HDMItoVGA connected to a fixed frequency Apple Monitor the M1212.
Here are the timings required in the config.txt of the Raspberry Pi
## 640x480 @ 67Hz
hdmi_group=2
hdmi_mode=87
hdmi_timings=640 0 64 64 96 480 0 3 3 39 0 0 0 67 0 30240000 1
Because the M1212 is composite sync we need to convert H + V sync to C-Sync.
6
BC548 680R
HSync ------------- ---------/\/\------o--------- CSync on Green
\ /!
\ /
---------
!
!
1k !
VSync ----/\/\----------
The Result is this:
And because the monochrome Apple 12" has the same timings this is also possible.