4. Configuring the PuPla/2
Page 9
PuPla/2
J2 (Jumper or Signal Input)
closed: PAK only, without 68000 on the PAK/FRAK
open: 68000 only or other accelerator, but no PAK
Connected to PAK J5 pin 2, when a switchable 68000 is
used on the PAK
J3 (Signal Input)
Connected to PAK U1 pin 20 via a 68 ohm resistor close to
U1
Not connected if there is no PAK
J4 (Signal Input)
Connected to pin C3 of Panther/2 bus adapter
Not connected when there is no Panther/2 adapter
4.2 The GALs
The PuPla/2 has two 20v8 GALs for flow control.
GAL1, labeled "PUFCTRL" on the silkscreen. This GAL is
responsible for controlling the buffering capabilities. The current
equation for this GAL is named "PUF2-004".
GAL2, labeled "AVICTRL" on the silkscreen. This GAL is
responsible for controlling the interrupt functions. Unfortunately,
the current equation has changed since delivery and is now called
"AVI5-06b". The tests with the first equation have shown that in a
very specific situation the GAL may cause a bus error (two
bombs) when writing to the network card under heavy load. This
does not occur under normal-to-medium load when reading from
the card. The reason for this behavior is quite strange: the "a"
version of the AVI5 equation only confirms a level 5 autovector
interrupt if the interrupt signal of the card is still present This has
the advantage that a non-autovector interrupt of the same level is
also possible.