For sale are new-made reproductions of the Ohio Scientific 540B color video interface board. These boards were produced from 4000 DPI scans of an original Ohio Scientific 540B board and are 1:1 with respect to trace and hole placement. They were run on standard thickness FR4 stock, which is thicker than original OSI stock, to reduce the excessive flex experienced with original Ohio Scientific products.

These boards have been scanned and reproduced as part of the Ohio Scientific Preservation Project. Full documentation is available in PDF format online. You can learn more about the OSI Preservation Project at http://osiweb.org or http://www.glitchwrks.com/osi -- please join the OSIweb forums! See our other listings for more reproduction and newly designed Ohio Scientific boards!

The OSI 540B supports the following features:

• 32x32 color video mode
• 64x32 color video mode
• Interface for OSI 542 keyboard
• Character memory from 0xD000 - 0xD7FF (will conflict with standard OSI CP/M)
• 4-bit color memory at 0xE000 - 0xE7FF
• Software controlled video mode register at 0xDE00

Full schematics provided courtesy of Dave Fenyes/osiweb.org at the documentation link provided.

The OSI 540B does conflict with memory requirements for both the OSI hard disk subsystem and standard OSI CP/M. This is not usually an issue as most systems using color video are disk or cassette based OS-65D systems. We do not currently offer a parts kit for this board.