Subject:      TECH: Berserk > Frenzy daughter bd description
From:         dfish@nyx10.cs.du.edu (David Fish)
Date:         1996/03/27
Message-Id:   <4jbq5s$br8@nyx10.cs.du.edu>
Organization: University of Denver, Dept. of Math & Comp. Sci.
Newsgroups:   rec.games.video.arcade.collecting

Hi Folks,

  Ok, here's the straight and skinny on the Frenzy daughter board for the ZPU-
1000. The board contains four 2732 EPROMs, an 82S123 PROM used as a memory map
decoder, a 74LS02 and a 74LS20. This board plugs onto the connectors J5 and J6
at the edge of the ZPU and into the data bus DIP shunt socket via a short 16
conductor ribbon/DIP plug. There are three pads on the daughter board which
are wired to points on the ZPU: one is 5 for volts; one is for the new CMOS
RAM enable line, and one for the external data bus direction control. This
configuration required two cuts on the ZPU, both done by snipping IC legs.

The modification to the original ZPU board accomplishes two things. It allows
the program memory to now be 20K, and it remaps the CMOS/NMOS 2K scratchpad
RAM from the original location of 800H thru 0FFFH up to 0F800H thru 0FFFFH.
It's only 1K but repeats it's image starting at location 0FC00H. The program
and data in EPROM now resides at 0000H thru 3FFFH and 0C000H thru 0CFFFH.

Screen RAM and Color RAM mapping remain unchanged, 4000H - 7FFFH and 8000H -
87FFH respectively. All I/O ports remain in thier original locations also.
The VFB board in my set is the same as in an original Berserk, no modification
was made to it, and none were made to either the sound or voice board. The
EPROMs in the voice board are the same as in Berserk.

The wiring is to complex to describe here so I'm making the schematic of the
daughter available to anyone interested. It's a B size drawing (11" X 17")
in postscript format. The cuts on the ZPU board are described on the schematic.
E-mail me if you'd like me to send you out a copy, it's 200K before UUencoding
so I'm not going to post it. I've also got the PROM and EPROMs archived if
anyone needs them.

                                                Dave

 Dave Fish                         |       "We want...Information. INFORMATION
 Melrose, MA  USA                  |              You won't get it!
    dfish@bev.etn.com   (work)     |        By hook or by crook we will"
    dfish@nyx.cs.du.edu (/work)    |                    _The Prisoner_