bmiller@burdvax.UUCP (10/02/87)
I need some clarification about the active levels on the user port
of the C64 when used as a TTL-level RS232 port. I am trying to interface to
an old Racal 212 modem which requires bipolar RS232 levels, and am trying to
determine which signals need extra inverters (1488/1489 IC's both invert).
The C64 Programmers Manual shows which signal names are assigned to which pins
on the user port, but does not clearly indicate whether signals are active
TTL high or TTL low. The signals of interest to me are:
From C64: TX DATA, RTS, DTR
To C64: RX DATA, CTS, CD (carrier detect), RI, DSR.
A clear description of which is the MARK state (for data) or ON state (for
control signals) would be very helpful. (Are you there, Fred Bowen?)
I am also curious as to whether most available terminal programs, including
Kermit, support a full handshaking interface, or contrarywise, what fraction
of a full interface is customarily supported.
Any and all help would be appreciated.
Bruce (bmiller@burdvax.prc.unisys.com)conway@hplb29a.HPL.HP.COM (Daniel F. Conway) (10/07/87)
I need some clarification about the active levels on the user port
of the C64 when used as a TTL-level RS232 port.
I am trying to interface to
an old Racal 212 modem which requires bipolar RS232 levels, and am trying to
determine which signals need extra inverters (1488/1489 IC's both invert).
Rather than fool around trying to drive an RS232 device with TTL levels,
just get a good level converter that plugs into the C-64. I use one from
Jameco, 1355 Shoreway Road, Belmont CA, (415) 592 8097; it works quite
well. It is listed on page 46 of their 1988 catalog for $39.95.
The adapter has switch-selectable polarities for the
modem control lines; using it with a good breakout box makes
interfacing rather easy (for RS-232, that is :-( ).
Dan Conway
hplabs!conway
Palo Alto, Californiaeravin@dasys1.UUCP (Ed Ravin) (10/13/87)
Building a Commie to RS-232 interface is easy and cheap ($10-$15). If
anyone following this discussion feels like building one, send me your
mail addresses and I'll post the gizmo that I built...
Ed
--
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