31 Jan
2002
31 Jan
'02
5:20 a.m.
Rob Kapteyn wrote:
I believe that the VDM-1 provided the prototype for PC
character graphics and extended-ascii "special" characters.
I noticed that the Commodare 64, which came later, pretty much copied it, with a few
additions.
>From memory, I think it was only 64 columns wide (by 32 lines ? )
I got VDM-1 manual here. The VDM and schematic got lost years ago.
16 lines of 64 characters with a 13.5 Mhz dot clock. The character
generator is 8 wide x 12 down 7 bit characters. Bit #8 inverted video.
The first 32 control characters may have graphic characters, depending
how control characters are handled.
--
Ben Franchuk - Dawn * 12/24 bit cpu *
www.jetnet.ab.ca/users/bfranchuk/index.html