Re: PET 4032 video RAM size/mirrors

From: MagerValp (MagerValp_at_Goth.Org)
Date: 1998-03-28 13:47:25

>>>>> "Andre" == Andre Fachat <a.fachat@physik.tu-chemnitz.de> writes:

Andre> I am wondering, having found no hard facts for my petindex:

I took a good look at my 8032-SK's motherboard today, and it might
answer a few of your questions.

Andre> The 4032 machines (with the upgradable-to-8032 board? are there
Andre> 4032 without CRTC

My board has a CRTC (HD46505, presumably a renamed version of the 68/
6545) and four "jumpers" like this:

 40   40   80
  7    6    5
  *    *    *
            |
            |
            |
            |
            |
  *    *    *

 80
 8*------------*

suggesting that resoldering these and changing the ROMs will give you
a 4032 with 2k of video memory.

Andre> What about the 8032? The reengineered schematics suggest it
Andre> being 2k, mirrored 2 times ($8000 and $8800).

My 8032-SK has 2k @ $8000 and open address space at @8800-8fff.

Andre> Another thing: the PET is supposed to be able to blank it's
Andre> screen with PIA1 CA2 (also used as IEEE EOI line). I assume
Andre> that this only works for non-CRTC machines, is this correct?

Well, nothing appears to happen on my 8032-SK.

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