Update for 20240220

A project log for Re-UD-80 - a larger display for Epson PX-4 / PX-8

The vintage Epson PX-4 and PX-8 computers have small LCD screens, with low contrast. This device fixes that problem.

fjkraanfjkraan 02/20/2024 at 13:490 Comments

All the components are finally in and soldered to the new 0.10 board. It was mainly my poor component inventory management and distractions why it took so long.

Before testing the new board, I adapted the old 0.8 prototype to the new video circuit,
and it looks quite good on my preferred display. Good enough to update the DIP-switche table:

ROM V5.21E:
1. off = 80 char./line, on = 40 char./line
2. ?
3. off = PAL, on = NTSC
4. off = white on black, on = black on white
5. ?
6. ?
7. ?
8. ?

ROM V7.11A:
1. off = NTSC, on = PAL
2-8. ?

The 7.11A version uses the DIP switch only for video mode. At least the 40/80 column mode is moved to software as it is mentioned in the ROM dump. This ROM also contains the intriguing text: "System Utilities Screen".

The 5.21E ROM version configures the EF9345 HS pin for both horizontal sync and vertical sync.

Board update

The 7.11A version uses both the HS and VS pins. This requires a small modification on both the old 0.8 and new 0.10 board for the 7.11A version.