22 Oct
2011
22 Oct
'11
12:50 p.m.
Hello Tony
I just found, by reading the interview with the game developer, that
the game uses a custom version of a calculator chip and not directly the
THat clacualtor chip copuld still be similar in concept to a
microcontroller. I know more about dekstop calcualtors than single-chip
ones (since the former are easier to investigate), but it wasn't
uncommon for a calculator to be essentialyl a general-purpose CPU running
the right firmware.
PPS-4/1. The PPS-4 seems to be a more general purpose.
About tracing the
game doesn't bring much as the game is just a single chip and a handful
of leds. Super super simple circuit.
Sure, that's what I expected. The point is that you can sometimes
indentify an IC by the pins used for power, groubdm the clock circuit
(crystal, LC tank cirucit, whatever)m, the reset RC circuit (if there is
one) and so on. THose don't nonrmally depeend on the programming of the
mask ROM.
On a side note: I looked in to the data sheets to the
PPS-4/1 that John Robertson was kind enough to dig out of his digital hideout. The PPS-4
was actually a bit more 'sophisticated' than I first thought. One other thing that
was unexpected was that the
y are powered eg. 0 and negative 9V. I wonder why
it's like that...
Sounds as though it might be PMOS logic, which tends to use a -ve supply
voltage
-tony