A new version of this project is available here
GLINK-LT is a modern clone of the Commodore VIC-1011A RS232 User Port adapter for Commodore 8-bit computers. The adapter is fully supported by the standard Commodore BASIC at up to 2400 baud. Jumpers allow the card to be configured as a UP9600 for 9600 baud operation in Novaterm and Striketerm. A reset button and a 5V header are also provided for added convenience.
The schematics is practically identical to the older GLINK-LT-A02 version. The only addition is a footprint for a 5V header that can be used to power an external device like a SD2IEC. The other change is only on the layout side as in the B00 version all components except the connectors are SMD.
Two MAX232 are used as RS232 level translators (U1 and U2). U3 inverts the control signals as expected by the original commodore software. R1, R2 and R3 provide reasonable default to the control lines in the case of 3-wire RS232 cable. Jumper blocks J3 and J4 enable UP9600 functionality.