Re: -5v and -12v Serial Ports

On 3 Jun 2007 00:16:22 GMT, Jasen <jasen@xxxxxxxxxxx> wrote:

On 2007-06-02, stratus46@xxxxxxxxx <stratus46@xxxxxxxxx> wrote:
On Jun 1, 7:38 pm, "Bart" <bborb@fusedotnet> wrote:

I believe the original spec for RS-232 levels was minimum +/- 3v.
Calling Jim Thompson for enlightenment. I'm surprised about the +/- 5
thing. I thought most everybody used a MAX232 (or knock off) to make
+/- 10 from the 5 volt supply.

most PCs use one of Jims MC1488s (or similar) to do the +/-12V, as PCI
(and ISA) slots make those voltages avaialable.
<snip>

Outside of my parts box, I haven't seen a 1488 or 1489 in a PC for
quite some time. They are though, if nothing else, nice little space
heaters. I forget which of the two, but one of them runs almost too
hot to touch long.

Jon
.