A new version of this project is available here
Both the commodore 64 and the 128 have a software UART implementation that limits the useful speed to 2400 bauds. To work around this limitation Dr. Evil Labs and later CMD produced the SwiftLink232 and turbo232 cartridges based on the 6551 ACIA chip. Both of these have been out of production for a very long time. GLINK232 is a modern replacement for the swiftlink232 allowing the commodore 64/128 to communicate at speeds up to 38400 bauds.
Similarly to the SwiftLink, the card can be configured using jumpers at either the $DE00 or $DF00 I/O address and can use either the NMI or IRQ interrupt line (most native software use NMI, but CP/M uses IRQ).
The card uses a 3.6864MHz crystal (double the standard for a 6551) to match the baud rate table of the SwifLink.
|C10||no stuff||no stuff||.1uF|
|R4-R11||no stuff||no stuff||0 ohm (one location only)|
|U4||no stuff||no stuff||74LS138|