Re: CBM-II Character Set and Colour Expansion (was: BASIC for the CBM-II/8088)

Add a 9th bit? How will that work? Sounds like it would add a lot of circuitry.
Right now my mod gives you 256 different characters on screen, but sacrifices the reverse set. there is no way to do reverse unless we add some attribute memory. That's my next step. Attribute memory could be colour, font, blink, underline or some combination... whatever makes sense with 8 bits. On my ColourPET+G I have 4 foreground + 4 background colours (RGBI digital), but I also have a mode where the 4 background bits are used to select 1 of 16 different fonts.for each character. For the 8088 card perhaps I could do 3 bits (8 colours) fg/bg and then 2 bits for blinking and something else.
Steve

      From: Mia Magnusson <mia@plea.se>
 To: cbm-hackers@musoftware.de 
 Sent: Sunday, July 15, 2018 3:23 PM
 Subject: Re: CBM-II Character Set and Colour Expansion (was: BASIC for the CBM-II/8088)
   
Den Sun, 15 Jul 2018 04:44:17 +0000 (UTC) skrev Steve Gray
<sjgray@rogers.com>:
> Sometimes the obvious stares you in the face. So, if I just reverse
> the upper 128 extended characters they will just get reversed again
> and come out normal. No need to mod the motherboard.... unless... Now
> I have to fix the extra phantom 9th pixel that gets turned on
> whenever RVS characters are shown.... I fixed my B128 by cutting a
> pin and I assume it will also work on the high-profile machines.
> (Anyone try this?) BTW, my machine's video RAM chip is soldered in,
> so I'll have to socket it if I'm gonna work on the Colour expansion
> too.

As eprom is so cheap today, wouldn't it be a good idea to add a 9th bit
as a compensation for that line which is solid black/bright with the
standard circuit?

Btw for the 8088 card at least inverted video is needed and two
intensities would be really good. Haven't had a look at the monitors
schematics but adding two different brightness levels as in MDA would
probably not be that hard. This assumes that all HP B's uses the same
monitor though.

For the LP machines it's of course simpler.


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