On the left is the PFC-FCON unit and on the right side the HKS Fuel Computer (silver front);
The HKS Fuel Computer I do not know a lot about, it would have controlled additional fueling on a lot of the early 80s HKS Turbo and Supercharger kits.
On the other hand I have a lot of information on the PFC-FCON often known as the black box FCON. There are three different types of PFC-FCON I have come across. These can be identified by PCB number in the pictures below.

The FC2 FCONs are very early pre 1988 models of the FCON. Unfortunately I don't have any catalogs or supporting documentation about what map sensor or EPROMs these units use. On this model FC2 is printed on the lower left hand corner of the PCB in the photo pictured to the right, a closeup of this area of the PCB is also shown in the left photo below,  there also is two other ways of identifying this FCON, the center photo is the label stating harness number and EPROM number, all FC2 PCB FCONs I have seen have one letter followed by two numbers to identify the EPROM chip number. This is the V05 section of the tag, also pictured on the right below is the EPROM chip with V05 printed on it.

The FC3 FCONs were produced between 1988 and 1993. They used the D Type EPROM chips and a Denso 0730 map sensor. I have some documentation and information about the EPROM chips for this FCON. On this model FC3 is printed on the lower right hand corner of the PCB in the photo pictured to the left, a closeup of this area of the PCB is also shown below on the left, There is also is two other ways of identifying this FCON, The center photo below is the label stating harness number and EPROM number all FC3 PCB FCONs have a D letter followed by three numbers to identify the EPROM chip number, this is the D116 section of the tag. Also pictured on the right below is the EPROM chip with D116 printed on it.

The FC4 FCONs were the last of the black box PFC-FCONs and were produced after 1993. They used the E Type EPROM chips and a Denso 6110 map sensor. I have some documentation and information about the EPROM chips for this FCON. On this model FC4 is printed on the lower right hand corner of the PCB in the photo pictured to the left, a closeup of this area of the PCB is also shown below on the left, There is also two other ways of identifying this FCON, The center photo below is the label stating harness number and EPROM number, all FC4 PCB FCONs have a E letter followed by three numbers to identify the EPROM chip number, this is the E104 section of the tag. Also pictured on the right below is the EPROM chip with E104 printed on it.