Description

The Oval Automation Ltd UD-80 is an external screen device for the vintage CP/M PX-4 and PX-8 computers. It allowes the output to be displayed on an 80 by 24 or 40 by 24 character monitor or television set. The interface is the PX-8 / PX-4 RS-232c port. The drivers are downloaded from the UD-80 itself in FILINK mode, FILINK being a native utility for these computers.

This project aims to create a replica of the original. Using mainly original parts which are still available online.

The project has resulted in an easy to reproduce device. The ROM firmware is copyrighted as is the original board design.

The recreated board-files will be available for free, I do not plan to sell these boards.

Details

The Oval UD-80 Display Controller is  based on a CP/M feature to redirect input and/or output, typically configured with STAT (see Fun with STAT).

The UD-80 displays the output (80*24 or 40*24) on a cheap TV compatible monitor (PAL or NTSC). Very sensible in the 1980's. The driver allows to add color information, but lacking the original manual it is unclear how.

The driver isn't compatible with the old OS-ROM (M25030CA), and it instead suggests the STAT option.

For the PX-4 more testing is needed, but the STAT command below works.

STAT CON:=TTY:

Here a review of the device from 1986:

Epson Connect review of the Oval UD-80 (198603)

There are two different firmwares available; 5.21E with a driver for the PX-8, and the patched 7.11c with a driver for the PX-4. Both firmwares probably work with both machines. The original 7.11A firmware does not work with the standard UD-80 and the Re-UD-80, as this firmware expects lightly different hardware (see the log on "The sync issue and two firmwares"). 

More Code: Re-UD-80 - a larger display for Epson PX-4 / PX-8 | Hackaday.io. Reposted with permission from the author. And if you want to explore more projects, please follow the author: fjkraan (Hackaday). He has many wonderful projects and is an excellent maker. Enjoy it!