Re: 6545 40/80 col register values

Well, I'd call it interleaved video memory instead of "double bus width", but let's not quibble over semantics.

I thought the 40 and 80 col. CRTC configurations might be the same since 80 columns are really essentially 40 columns with each character split in two halves, but wanted confirmation for a little project being discussed on the VC forum; the differences in the 50Hz versions are interesting though...

Thanks, Steve!

m
  ----- Original Message ----- 
  From: A.Fachat 
  To: cbm-hackers@musoftware.de 
  Sent: Wednesday, April 25, 2012 1:43 AM
  Subject: 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
  -- 
  Diese Nachricht wurde von meinem Android-Mobiltelefon mit K-9 Mail gesendet.




  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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