Key:
This assumes that connector 1 is the connector on the Alpha, Multia,
or PC.

DB25 - standard DB25 with EIA RS232C definitions.
PC9 - DB9 with IBM PC compat pinouts
AP9 - Alpha PC164 DB9 pinouts
MP(1/2) - Multia DB25 dual com port connector pinouts
DIR - signal reference for connector 1

Straight thru cable:
------ CONNECTOR 1 ---  ----- CONNECTOR 2 ------

PC9  AP9 MP1 SIGNAL DIR SIGNAL    PC9     DB25
            
01   01  08  DCD  <-I-- DCD       01       08
02   03  02   TD  --O-> TD        02       02 Note 1
03   02  03   RD  <-I-- RD        03       03 Note 2
04   04  20  DTR  --O-> DTR       04       20
05   05  07  GND  ----- GND       05       07
06   06  06  DSR  <-I-- DSR       06       06
07   07  04  RTS  --O-> RTS       08       04
08   08  05  CTS  <-I-- CTS       07       05
09   09  22   RI  <-I--  RI       09       22

MP2  SIGNAL    SIGNAL    PC9     DB25             

11    DTR  --O-> DTR      04       20
12    DCD  <-I-- DCD      01       08 
14     TD  --O-> TD       02       02
16     RD  <-I-- RD       03       03
13    CTS  <-I-- CTS      08       05
19    RTS  --O-> RTS      07       04
23    DSR  <-I-- DSR      06       06
25     RI  <-I-- RI       09       22
      GND  ----- GND      05       07 Note 3 

Note 1 - PC164 docs show this, note it is different from IBM PC.  
Note 2 - PC164 docs show this, note it is different from IBM PC.
Note 3 - in my multia docs, this conneciton is not identified.
I recommend tying two leads to the Multia DB25 pin 7 so that 
there is a common ground between the two connections.