13 Feb
2006
13 Feb
'06
7:18 a.m.
I want one anyway. I WANT IT I WANT IT! Another
minimum mode 8088 I seem to perceive. Used to think
I think so, but I would have to find the schematic to be sure.
that amounted to an 8085, but its not limited to 64k.
Chuckie also chose a non-conformist Hitachi crt
I thought it was just amother 6845-a-like. But it addresses 2K*16 bits of
SRAM, some of the outputs of which are used as part of an address to the
main system DRAM which cotnains the character bitmaps (!). Not
suprisingly, the Apricot does the same thing.
There are enough outputs taken from the SRAM to form that address that
each character cell on the screen can have a different bitmap assigned to
it, thus allowing a rather eccentric bitmapped graphics mode.
Oh yess, the brightness and contrast of the monitor are controlled by 2
3-bit ressitor ladder DACs driven by yet another 6522...
-tony