can rPi drive PC-bidirectional Par-port?

[Avoi...@gmail.com]

Probably the PC parallel-port has TTL specs?

So them 3.3V CMOS should drive it ?

Can the 'bidirectionality' of the Par-port be tested/confirmed
without hardware tool, ie. by software?

Since eg. IOMEGA par-port assumed at least a 4bit-wide
bidirectionality, perphaps all post-70's were bidirectional?

== TIA.

[Johann Klammer]

Avoi...@gmail.com wrote:
> Probably the PC parallel-port has TTL specs?
>
> So them 3.3V CMOS should drive it ?
>

I guess that would work, if your rPi is 5V tolerant...
Resistors and z-diodes won't harm if it is not.

> Can the 'bidirectionality' of the Par-port be tested/confirmed
> without hardware tool, ie. by software?
>

I believe you can switch the parport to input and see if the bits
flip... They will, if there's some line-noise nearby and nothing
connected on the output. If you want to be sure you'll need to bridge at
least two pins(I forgot which)

> Since eg. IOMEGA par-port assumed at least a 4bit-wide
> bidirectionality, perphaps all post-70's were bidirectional?
>
> == TIA.
>

4bit modes were done via status line reads using unidirectional ports...
I believe interlnk/laplink worked that way...
Not sure what IOMEGA does...

Parallel Port Information System can test some things. (It's on ultimate
boot cd, but gives occasional false output on my box)

[Anssi Saari]

Avoi...@gmail.com writes:

> Since eg. IOMEGA par-port assumed at least a 4bit-wide
> bidirectionality, perphaps all post-70's were bidirectional?

The PC printer ports were bidirectional at least in the sense that they
had five status inputs which could be used as data inputs. Even the
control outputs could be fairly easily used as inputs which meant a
total 9 input pins.

Bidirectional ports have a control bit to set the data pins to inputs or
outputs or to be exact, eanble or disable the output drivers.

So, probably you can talk to a PC parallel port but I'd rather use
ethernet or serial (RS-232) for PC communication.

[Unknown]

Yes but, I want to interface to the most primitive PCs.
Ethernet is a higher level of complication.
And IIRC RS232 won't interface with rPi's 3.3V [MOS ?],
but par-port will.

WDYS?

[Rob]

You primitive PCs will likely have a 5V par port?
Maybe not so bad when it is still TTL, but when it is MOS...?

For RS232 you can put a MAX-3222 or MAX-3232 inbetween.

[David]

At Fri, 05 Apr 2013 07:52:54 +0000, Avoid9Pdf rearranged some electrons to
write:

Raspberry Pi I/O is not 5V tolerant.

[Michael Black]

Ihadn't thought of that. So no handshaking.

I was thinking 3.3v into the parallel port (assuming it did allow input)
was a bit iffy, it would depend on the circuitry of the printer port it's
feeding. It might work fine, or it might be noisy, not enough absolute
difference between high and low.

But if the Pi doesn't want more than 3.3V, then nothing can come back to
it until someone adds some buffers between the two to deal with the
voltage variant. At which point, they might as well add some buffers for
the signal lines going to the other computer.

At which point, one might as well go RS-232 and just add line drivers and
receivers. One thing the clueless didn't specify earlier was that the Pi
board apparently includes a serial I/O among those "general purpose I/O
pins", so all that's lacking is the drivers and receivers.

Or, didn't the Commodore 64 just output TTL on the serial port? I seem to
recall endless articles about adding RS232 drivers and receivers so the
computer would work with real RS232. Get one of those, and you've got
your 40character wide terminal, only it would be +5v ttl, not 3.3V.

Either somebody has to learn to solder, or the simpler solutions of the
ethernet port, or the intended hooking the board up to a USB keyboard
(easily found in the garbage, though not as common as PS/2 keyboards yet)
and to a DVI or HDMI monitor or TV set.

Or, add a string of 8 toggle switches to input data into the Pi, and a
string of 8 LEDs to indicate output from the Pi, and write a monitor to
make use of them. It wsa good enough in the days of the Altair 8800
(though the front panel hardware was extensive) or the days of the Cosmac
Elf (the RCA 1802 CPU was set up for jamming data onto the bus, so it was
easy to have a front panel, and no monitor in ROM needed). But it's a
massive step down when the PI is so fancy that it can run full blown
Linux, and is almost as good as the 1GHz/512meg computer I was using till
this past October.

Michael

[Michael Black]

He has to define "primitive". That Sun 3/50 someone gave me has ethernet,
but Macs of that vintage didn't. It was't until relatively recent times
that ethernet becamse common (after things like ARCnet), but I think you
can go back 20 years and while ethernet wasn't standard, there were cards
for the ISA bus in the "IBM PC". Of course, you'd need an operating
system that would make use of the ethernet card.

Michael

[The Natural Philosopher]

No. you needed some third party software.


And don't forget token ring as well..

> Michael
>
>
>> For RS232 you can put a MAX-3222 or MAX-3232 inbetween.
>>

--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

[Rob Morley]

On Mon, 08 Apr 2013 10:21:29 +0100
The Natural Philosopher <t...@invalid.invalid> wrote:

> And don't forget token ring as well..
>

Please can we forget token ring?

[The Natural Philosopher]

well..I get the point..

[Stanley Daniel de Liver]

but there were *no* collisions!


--
It's a money /life balance.