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Rob Hagemans 8ca7f9ee46 move images and extractor to context		2023-01-02 18:24:21 +00:00
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context	move images and extractor to context	2023-01-02 18:24:21 +00:00
Datapoint-8600.draw	Datapoint 8600	2023-01-02 17:23:59 +01:00
README.md	Readme	2023-01-02 18:23:05 +00:00

README.md

Datapoint font

This directory contains the ROM font of the Datapoint 8600.

ROM images were read out by the crew of the museum of computer history in Visselhövede, Germany, and are provided here:

905-007-1.bin 905-008-1.bin

The font data is in 905-008-1.bin and starts at $10AF.

Font data in the ROM image is not directly mapped as a character generator but is read by the "bios" of the machine and stored into the actual character RAM area. The font is a 8x12 font, but only uppercase characters were available, with the lowercase characters later loaded by the operating system (RMS 2.8.J) for which unfortunately no data exists.

The font data is organised as nine bytes for each character, with the MSB of these data bytes always 0 for inter-character spacing. Therefore, data exists for 7x9 bitmaps. Three empty lines are added when loading this font, one line on top and two lines at the bottom as seen when comparing with the cursor on the real machine in which has all twelve lines set.

Bytes with MSB set denote the place in the character table (when masked with $7F). Then nine bytes of graphics data follow.