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

The ~VGGO comes into the clear pin of a ls74, the data for this flip-flop is
OP0 (outputs HALT and ~HALT) and it is clocked with ~STROBE3. ~STROBE3
comes from an address decoder based on the state machine (back to that dang
sm).

~VGGO also goes to another ff where it is the SET signal, the output of that
is AVG0. But the data from it is based on STATE2 and I believe AVG0 never
changed.

David

----- Original Message -----
From: Jess Askey <jess@magenta.com>
To: <vectorlist@lists.cc.utexas.edu>
Sent: Monday, August 23, 1999 9:14 AM
Subject: 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 12:46:18 1999