Re: Help: AVG state machine (BZ / RB / Tempest)

Doesn' the VGGO line clear the HALT line via a direct flip-flop? If so, you should be able
to do a lot of this troubleshooting without the 9010A.
  The basic process of the VGGO is....
     - clear halt
     - reset the VG address bus to VGRAM,0x000
     - start executing VG code at VGRAM,0x000

Im not sure what happens if you try and assert VGGO if the VG is not
halted tho. Normally the 6502 software needs to check for this before
asserting VGGO. Maybe your VG is not halted yet (for some unknown reason)?
  

> David Shoemaker wrote:
>
> I am going to be dreaming about this damn thing I just know it.
>
> Working on a BZ boardset. Using my 9010 to download the test program from the cat box
> manual. When I do the VGGO nothing happens.
>
> I have read the program back out of memory and that is all ok. (I am starting to really
> like the 9010).
>
> As far as I can see the VGGO isn't clearing the HALT line because the OP0 and ~STROBE3
> lines are not doing the correct thing.
>
> As far as I can tell this is being caused by the state machine not doing anything. But
> I am getting pretty confused on its startup state. If I reset the board a few times I
> can get most anything I want out of the OPx lines. The STROBEx and LATCHx all stay
> consistently HIGH. Along with the STATEx all being low.
>
> Has anyone tried to decode the state prom and figure out what in the blazes is going on
> in here?
>
> Clay you built an AVG replacement which should be nothing more than the BZ / Tempest AVG
> right? So you MUST have figured it all out to make sure it worked? PLEASE tell me you
> know how to debug this stinking AVG.
>
>
> (low wimpering voice) Help me please.........
>
> I have 6 boardsets and they all have problems in the AVG. URG.
>
> I will collect all the stuff I have done with the 9010 and pass it on to Al for spies
> tonight. I have the AVG test app along with BZ memory map stuff etc plus some notes.
>
> David
>
Received on Mon Aug 23 11:18:15 1999