This is expected to show a redefined glyph that resembles the vulgar fraction 1/3.
However, PC-BASIC does not allow changing low-memory addresses 124--126, and instead needs the user to overwrite the original addresses where the font is stored:
This in turn does not work on GW-BASIC on DOSBox. Note however that the original code does not work on DOSBox either and shows a glyph made up of random dots. It may well be that DOSBox's emulation does not allow setting these memory ranges.
Further investigation needed to see if the original font address can be overwritten in GW-BASIC (not on DOSBox) or if this is a ROM area instead.
PC-BASIC can change the 8-bit font in CGA mode, but the way this works is different from GW-BASIC.
Consider the code from PC-Magazine's PEEKs and POKES articles (12 Nov 1985 and 26 Nov 1985):
This is expected to show a redefined glyph that resembles the vulgar fraction 1/3. However, PC-BASIC does not allow changing low-memory addresses 124--126, and instead needs the user to overwrite the original addresses where the font is stored:
This in turn does not work on GW-BASIC on DOSBox. Note however that the original code does not work on DOSBox either and shows a glyph made up of random dots. It may well be that DOSBox's emulation does not allow setting these memory ranges.
Further investigation needed to see if the original font address can be overwritten in GW-BASIC (not on DOSBox) or if this is a ROM area instead.