Setting Up The PSI BOX.
PSI BOX Reference
In general, the buffer is divided as follows. Half of the
available ram is used for the Centronics port and half is used for
the RS232 port. The RS232 port partitions its share of the ram
buffer evenly between input and output. With the Centronics and
RS232 ports both being buffered there is no need for the IEEE
port to be buffered.
Due to the many different modes of operation of the PSI
BOX the ram buffer partition may be different from that
described above. The PSI BOX alters the general case to suit the
mode actually in use.
When the buffer is disabled then each of the active ports
has a 2 byte buffer. This two byte buffer gives a better flow of
data than actually having no buffer at all!.
Figure 1-2. Buffer Option.
_______________________
DIP 8
BUFFER OPTION CHOSEN.
_____
_____________________
0=Off
NO BUFFER IN USE.
1=On
BUFFER ENABLED
Figure 1-3. The Buffer Allocation.
_____________________________
Mode
RS232
RS232
CENTRONICS
CENTRONICS
____
_____
_____
__________
__________
INPUT
OUTPUT
INPUT
OUTPUT
_____
______
_____
______
1
8192
8192
14848
0
2
8192
8192
0
14848
3 0
16128
14848
0
4
16128
0
0
14848
5
0
0
30720
0
6
30720
0
0
0
7
15360
15360
0
0
8
28672
2048
0
0
It is anticipated that enhancements to the basic PSI BOX
will be available as time progresses. These enhancements will
probably include memory upgrades, improvements to the ROM
based software and further input - output options.
Chapter 1
Page 5
