Vector Graphic Z80 Board
The Vector 1 started off with an 8080 CPU. This was quickly replaced with this Z80 CPU card. Early cards ran at 1 MHz but later were upgraded to 2 MHz.

The Vector Graphic Z-80 board was designed around the Z-80 microprocessor chip. The board was fully S-100 bus compatible, providing interchangeability between systems. All input and output lines were fully buffered. Loading on the bus was no more than 1 TTL load. In addition, the board had the necessary circuitry to work well with dynamic RAM boards, such as Vector Graphic's 48K board. Simplicity of design has been stressed to enhance reliability of operation by the use of MSI and LSI integrated circuits. The board put the Z80's RFSH* signal on to pin 66 of the S-100 bus. This allowed their 48K dynamic RAM board to easily work with the card.
 
The manual for this board can be obtained here