prindle@NADC.NADC.NAVY.MIL (Frank Prindle) (05/03/90)
Your MAC may accept TTL signals, but please note that the TTL signals produced and accepted by the C64 RS-232 user interface are INVERTED TTL signals (i.e. +4V at the 64 needs to be -12V (or 0V TTL) at the MAC, and 0V at the 64 needs to be +12V (or +4V TTL) at the MAC. So I reiterate, you must have a C64 to RS-232 interface, if for nothing else, to invert the sense of the TTL signals (the SUPRA peak modem interface does just that, without shifting to the +/- RS-232 levels, which makes that interface work for some modems, but not all!). Sincerely, Frank Prindle Prindle@NADC.navy.mil