Re: 6545 40/80 col register values

That shows register 2 as giving the visible number of chars.

That's 40 for both 40 and 80 cols is done in hardware due to bandwith issues. Double video memory bus width on std 8032, faster RAM on the 8296.

Look up crtc operation on the petindex pages

André
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Steve Gray <sjgray@rogers.com> schrieb:

I disassembed some editor roms and here's what I found...

 

These are for BASIC4 machines.

 

40 col, normal, 60Hz:

Table 1>   31 28 29 0F 20 03 19 1D 00 09 00 00 10 00 00 00 00 00   > Table at $E7B1,  JSR $E606

Table 2>   31 28 29 0F 28 05 19 21 00 07 00 00 10 00 00 00 00 00   > Table at $E7C3

 

80 col, normal, 60Hz:

Table 1>    31 28 29 0F 20 03 19 1D 00 09 00 00 10 00 00 00 00 00  > Table at $E72A,  JSR $E07A

Table 2>    31 28 29 0F 28 05 19 21 00 07 00 00 10 00 00 00 00 00  > Table at $E73C

 

40 col, normal, 50Hz:

Table 1>    31 28 29 0F 27 00 19 20 00 09 00 00 10 00 00 00 00 00 > Table at $E7B1,  JSR $E60F

Table 2>    31 28 29 0F 31 00 19 25 00 07 00 00 10 00 00 00 00 00 > Table at $E7C3

 

80 col, business, 50Hz:

Table 1>     32 28 28 08 26 02 19 20 00 09 00 00 10 00 00 00 00 00 > Table at $E72A, JSR $E07A

Table 2>     32 28 28 08 30 00 19 25 00 07 00 00 10 00 00 00 00 00 > Table at $E73C

 

*Table 1/2 are Text/Graphics modes.

*The 40 and 80 column machines use the same values

*The 50 and 60 Hz models are slightly different.

*Most registers are the same except:

  00-Total Characters per line (usually 31hex. why 32 for 80-b-50?)

  04-Number of Display lines

  05-Vertical Position

  07-Height from bottom of screen

  09-Number of scanlines per row (graphics/text mode)

* Tables and code are at different addresses

 

Steve


 

From: MikeS <dm561@torfree.net>
To: cbm-hackers@musoftware.de 
Sent: Tuesday, April 24, 2012 3:10:13 PM
Subject: 6545 40/80 col register values


By any chance does any one have handy the values to load into the PET's 6545
registers to initialize it, both for 40 and also 80 columns?

TIA,

mike


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