TIM-011 video on Sony CPD-1302

A project log for TIM-011: FPGA-based VGA and PS/2 keyboard adapter

Trying to connect vintage TIM-011 home computer with PS/2 keyboard and VGA using a FPGA developer board

zpekiczpekic 05/10/2021 at 01:400 Comments

I was hunting at the local PC-recycle for a monitor that could be connected directly to my vintage C-128  natively without the usual converter (Gonbess + other) and cable mess. I could not believe my luck when I found a Sony CPD-1302 with Trinitron tube (good old particle accelerator!) 

This monitor appeared in the ideal moment when the classic home computers from the 80ies were still around, but the PC revolution started - VGA was expensive and tied first to PS/2, most PC users had MDA, CGA or EGA (all digital) - or maybe PGA which was always a rarity given how high-end expensive it was (analog to be able to produce 256 colors). This monitor supports all of them:

Looking at the CPD-1302 timing charts, it looked that the timing would match:

Most importantly (where many vintage computer / monitor pairings fail), the CPD-1302 has a "smart" detection of VSync, extracting it from composite HVSync, or it can be fed directly.

Connection was simple:

TIM-011CPD-1302Color (on CPD side reference pics below)
V0one out of R, G, B, Ired, green, blue, intensity is white
V1one out of R, G, B, Ired, green, blue, intensity is white

Here are some experiments:

Analog mode

Connecting "I" for a color as expected rendered only 2 color image as the "intensity" digital signal is ignored. But the other color signal (green in this case) is recognized as "analog".


With the same I + G switching to "digital" mode, suddenly 4 "colors" appear, as expected. However one would expect black, and 3 shades of green but monitor shows the darkest green as brownish/grayish?

Now replacing the I+G with B+G:

As expected, this allows black, blue, green and cyan:


In all probability, CPD-1302 would work well with a "real" TIM-011, as it works in all modes (even analog!) with the FPGA implementation of its video circuit. 

There was a problem with vertical sync - as seen above the frequencies are somewhat different. This caused flicker, until the image was adjusted towards top of screen. This made the picture stationary but lost few top line of the screen. Not a too big problem in text modes (as the action happens near the bottom of screen) but annoying for graphics or games.