gnome@oliven.UUCP (03/27/84)
B U L L E T I N on cartridge modifications !!!
Well, after looking into some of the new cartridges
(namely Web Wars and animaction) I have found that
GCE has thrown me a few curves!
Curve #1
The Web Wars Cart (and possibly others) has
an 8k x 8 ROM in it. The pinouts are only slightly
different than the older 4K carts. But this will
be a bit of a problem with the EPROM mod that I just
published on the net. Basically, the new 8K rom is
also in a 24 pin package (same number of pins as a 2732),
but the equivalently large EPROM (a 2764) has 28 pins.
There are a couple of solutons -
1) treat all carts like 8k ROMS
and use i2764's as the standard
EPROM for the present time.
2) Just wait until there is a solid
hacking standard that everyone likes.
(this is especially true because of
Curve #2 ! )
Curve #2
The Animaction cartridge was even more of a
surprise! First off, it had no screw holding it together.
Instead, it was glued around the edges. Upon opening it
up, there was an evident difference!
It contains -
1) an 8K ROM (like WebWars)
2) an HM6116 CMOS Static ram
3) a 74LS139 dual 2-4 decoder (address decode)
Basically the low order address bits of the RAM and ROM
(A0 through A10) are tied together as are the data lines.
The 74LS139 uses A12-A14 to select between RAM and ROM
address areas.
********************************************************
Maybe a more universal cartridge would be one that can
use both 2732's, 2764's (8Kx8) and RAM?
When I get more information, I'll pass it along.
Please send me your ideas on the subject.
Gary
(hplabs,allegra)oliveb!oliven!gnome
PS- Werner (ARPA), I am receiving your messages, but can't
get through the local ARPANET gateways... I'm stuck!