This is the modified version of the old but cheap RS232 interface. Together with nice schematic diagram you can look some PCB designs. The following options were added:

• Now works with Daniel Dallmann's SLIP & MiniTerm programs.
• Should work with Novaterm 9.6 at 9600bps.
• DSR disable jumper (for some software).

You can use MC1488/1489, GD 75188/75189 or other chips with similar functions and layouts:

1488 PINOUT 1489 PINOUT

+-------+ +-------+ -12V --|1 \/ 14|-- +12V RS232/In1 --|1 \/ 14|-- Vcc TTL/In1 --|2 13|-- TTL/In4b Gate1 --|2 13|-- RS232/In4 RS232/Out1 --|3 12|-- TTL/In4a TTL/Out1 --|3 12|-- Gate4 TTL/In2a --|4 11|-- RS232/Out4 RS232/In2 --|4 11|-- TTL/Out4 TTL/In2b --|5 10|-- TTL/In3b Gate2 --|5 10|-- RS232/In3 RS232/Out2 --|6 9|-- TTL/in3a TTL/Out2 --|6 9|-- Gate3 GND --|7 8|-- RS232/Out3 GND --|7 8|-- TTL/Out3 +-------+ +-------+

74LS04 PINOUT

+-------+ inA --|1 \/ 14|-- Vcc 1N914 layout: outA --|2 13|-- inF inB --|3 12|-- outF |\ | Have a mark outB --|4 11|-- inE ----| >|---- <--- (color point) inC --|5 10|-- outE |/ | on that side outC --|6 9|-- inD GND --|7 8|-- outD +-------+