Reply by Jan Panteltje September 27, 20172017-09-27
On a sunny day (Wed, 27 Sep 2017 03:16:12 -0700 (PDT)) it happened whit3rd
<whit3rd@gmail.com> wrote in
<8b01039c-7469-4161-a0e7-c6b8a761d095@googlegroups.com>:


>Sure did. The serial communications controller mode was called 'FM0'. >It wasn't just a UART, it was kinda... smart. Zilog 8530. That was >in all the Macintosh models roughly 1984-2000, so even the oldest >Mac128 would do networking.
Ah yes, good old 8530, did a Z80 based baycom packet radio modem with it http://panteltje.com/panteltje/z80/system14/diagrams/component_layout.jpg http://panteltje.com/panteltje/z80/system14/diagrams/baycom_diagram1.jpg AX25 etc ... wrote all that code in Z80 asm, 27 MHz packet radio. And I still use the TCM3105 in an RC airplane com link... was posted here years ago. SDLC HDLC... And Linux still has the drivers and docs: /usr/src/linux-2.6.37.6-p1_small/Documentation/networking/z8530drv.txt or use locate z8530drv.txt Do not see the datasheet on this PC anymore. Things change... Threw away the whole huge z80 system one day. Too much stuff...
Reply by whit3rd September 27, 20172017-09-27
On Tuesday, September 26, 2017 at 10:36:30 PM UTC-7, upsid...@downunder.com wrote:
> On Tue, 26 Sep 2017 18:42:27 -0700 (PDT), whit3rd <whit3rd@gmail.com> > wrote: > > >On Tuesday, September 26, 2017 at 4:11:37 AM UTC-7, upsid...@downunder.com wrote: > >> On Mon, 25 Sep 2017 22:59:43 -0700 (PDT), whit3rd <whit3rd@gmail.com> > >> wrote: > > > >> >and RS-423 with > >> >terminators (sold widely as LocalTalk by Apple, with third parties making > >> >ports that work for Windows) does good fast serial with (nominally) > >> >about 500m wire limits.
> >> Anyway, claiming 500 m for any single-ended non-isolated system is > >> really stupid in the real world.
> >The RS-423 serial ports did take a transformer to network. > > Transformer WTF ? > > That would require Manchester coding or similar to get rid of the DC > component, not very usable for traditional NRZ signaling.
Sure did. The serial communications controller mode was called 'FM0'. It wasn't just a UART, it was kinda... smart. Zilog 8530. That was in all the Macintosh models roughly 1984-2000, so even the oldest Mac128 would do networking.
Reply by September 27, 20172017-09-27
On Tue, 26 Sep 2017 18:42:27 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Tuesday, September 26, 2017 at 4:11:37 AM UTC-7, upsid...@downunder.com wrote: >> On Mon, 25 Sep 2017 22:59:43 -0700 (PDT), whit3rd <whit3rd@gmail.com> >> wrote: > >> >and RS-423 with >> >terminators (sold widely as LocalTalk by Apple, with third parties making >> >ports that work for Windows) does good fast serial with (nominally) >> >about 500m wire limits. >> >> Is that RS-423 (a.k.a DEC-423) shit still around ? That was supposed >> to be RS-232 compliant. Of the first batch of VT-220 terminals we >> received, the transceiver chips were replaced all but one during the >> warranty period. >> >> Anyway, claiming 500 m for any single-ended non-isolated system is >> really stupid in the real world. A balanced system like RS-422/485 >> could work 1000 m at 115k2 bits/s provided that the connection is >> isolated (no ground potential issues). > >The RS-423 serial ports did take a transformer to network.
Transformer WTF ? That would require Manchester coding or similar to get rid of the DC component, not very usable for traditional NRZ signaling.
>The >drivers, and receivers, had virtually NO problems, they were >AMD's AM26LS30 and AM26LS32. Some connector wizardry >was employed, and two-port backbone connectors, so any unoccupied connector >got the right termination resistor applied (until you plugged something into it). > >The biggest problem: everyone who wired to an RS-232 plug forgot that >they wanted the negative output signal.
Reply by whit3rd September 26, 20172017-09-26
On Tuesday, September 26, 2017 at 4:11:37 AM UTC-7, upsid...@downunder.com wrote:
> On Mon, 25 Sep 2017 22:59:43 -0700 (PDT), whit3rd <whit3rd@gmail.com> > wrote:
> >and RS-423 with > >terminators (sold widely as LocalTalk by Apple, with third parties making > >ports that work for Windows) does good fast serial with (nominally) > >about 500m wire limits. > > Is that RS-423 (a.k.a DEC-423) shit still around ? That was supposed > to be RS-232 compliant. Of the first batch of VT-220 terminals we > received, the transceiver chips were replaced all but one during the > warranty period. > > Anyway, claiming 500 m for any single-ended non-isolated system is > really stupid in the real world. A balanced system like RS-422/485 > could work 1000 m at 115k2 bits/s provided that the connection is > isolated (no ground potential issues).
The RS-423 serial ports did take a transformer to network. The drivers, and receivers, had virtually NO problems, they were AMD's AM26LS30 and AM26LS32. Some connector wizardry was employed, and two-port backbone connectors, so any unoccupied connector got the right termination resistor applied (until you plugged something into it). The biggest problem: everyone who wired to an RS-232 plug forgot that they wanted the negative output signal.
Reply by September 26, 20172017-09-26
On Mon, 25 Sep 2017 22:59:43 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Monday, September 25, 2017 at 12:56:18 AM UTC-7, David Brown wrote: >> On 23/09/17 04:42, Tim Williams wrote: >> > "rickman" <gnuarm@gmail.com> wrote in message >> > news:oq49e4$tqk$1@dont-email.me... >> >>> Thanks, we'll eschew. RS-232 may be old and slow but works.... > >> >> It's also not multi-master... I guess you can roll your own. >> > >> > RS-485 is a solved problem, cheap, and noise tolerant. Or CAN, if you >> > don't mind a little more hardware (often provided in MCUs) and more >> > automation as far as the bus dealing with bus-y problems all by itself. >> > >> > These might be a little hungry, or overly robust. If you need lower >> > current consumption, and the signal doesn't have to leave the board, an >> > open collector bus (like I2C) is still a good idea. >> >> Or you can use CAN controllers in microcontrollers, but with a simple >> open collector bus. You get the best of all worlds then > >Well, not ALL worlds. >Ethernet has better distance,
10Base2/5 and 10BaseT with hubs had only CD (Collision Detect) arbitration. On 10/100/1000BaseT with some extra hardware (switches) is needed to queue the messages to other ports.
>and RS-423 with >terminators (sold widely as LocalTalk by Apple, with third parties making >ports that work for Windows) does good fast serial with (nominally) >about 500m wire limits.
Is that RS-423 (a.k.a DEC-423) shit still around ? That was supposed to be RS-232 compliant. Of the first batch of VT-220 terminals we received, the transceiver chips were replaced all but one during the warranty period. Anyway, claiming 500 m for any single-ended non-isolated system is really stupid in the real world. A balanced system like RS-422/485 could work 1000 m at 115k2 bits/s provided that the connection is isolated (no ground potential issues).
>Open collector is kinda... IEEE-488. Short distance and low bitrate.
TTL Open collector systems, such as Unibus can do about 15 m in a flat cable. However, the real show stopper is the 0.4 V noise margin in the TTL "0" state. We had to connect the CPU and each disk unit drive frames with 5 cm wide copper strips in an old building with TN-C electrification to keep the CPU/disk communication error rate at a reasonable level.
Reply by David Brown September 26, 20172017-09-26
On 26/09/17 07:59, whit3rd wrote:
> On Monday, September 25, 2017 at 12:56:18 AM UTC-7, David Brown wrote: >> On 23/09/17 04:42, Tim Williams wrote: >>> "rickman" <gnuarm@gmail.com> wrote in message >>> news:oq49e4$tqk$1@dont-email.me... >>>>> Thanks, we'll eschew. RS-232 may be old and slow but works.... > >>>> It's also not multi-master... I guess you can roll your own. >>> >>> RS-485 is a solved problem, cheap, and noise tolerant. Or CAN, if you >>> don't mind a little more hardware (often provided in MCUs) and more >>> automation as far as the bus dealing with bus-y problems all by itself. >>> >>> These might be a little hungry, or overly robust. If you need lower >>> current consumption, and the signal doesn't have to leave the board, an >>> open collector bus (like I2C) is still a good idea. >> >> Or you can use CAN controllers in microcontrollers, but with a simple >> open collector bus. You get the best of all worlds then > > Well, not ALL worlds. Ethernet has better distance, and RS-423 with > terminators (sold widely as LocalTalk by Apple, with third parties making > ports that work for Windows) does good fast serial with (nominally) > about 500m wire limits. > > Open collector is kinda... IEEE-488. Short distance and low bitrate. >
OK, not /all/ worlds. It only makes sense for local connections, such as between devices on a board or on closely-coupled boards. But the context was in comparison with I&sup2;C, and anywhere that I&sup2;C would work, CAN with an open collector bus would also work - just with much easier multi-mastering.
Reply by whit3rd September 26, 20172017-09-26
On Monday, September 25, 2017 at 12:56:18 AM UTC-7, David Brown wrote:
> On 23/09/17 04:42, Tim Williams wrote: > > "rickman" <gnuarm@gmail.com> wrote in message > > news:oq49e4$tqk$1@dont-email.me... > >>> Thanks, we'll eschew. RS-232 may be old and slow but works....
> >> It's also not multi-master... I guess you can roll your own. > > > > RS-485 is a solved problem, cheap, and noise tolerant. Or CAN, if you > > don't mind a little more hardware (often provided in MCUs) and more > > automation as far as the bus dealing with bus-y problems all by itself. > > > > These might be a little hungry, or overly robust. If you need lower > > current consumption, and the signal doesn't have to leave the board, an > > open collector bus (like I2C) is still a good idea. > > Or you can use CAN controllers in microcontrollers, but with a simple > open collector bus. You get the best of all worlds then
Well, not ALL worlds. Ethernet has better distance, and RS-423 with terminators (sold widely as LocalTalk by Apple, with third parties making ports that work for Windows) does good fast serial with (nominally) about 500m wire limits. Open collector is kinda... IEEE-488. Short distance and low bitrate.
Reply by David Brown September 25, 20172017-09-25
On 23/09/17 04:42, Tim Williams wrote:
> "rickman" <gnuarm@gmail.com> wrote in message > news:oq49e4$tqk$1@dont-email.me... >>> Thanks, we'll eschew. RS-232 may be old and slow but works.... >> >> It's also not multi-master... I guess you can roll your own. > > RS-485 is a solved problem, cheap, and noise tolerant. Or CAN, if you > don't mind a little more hardware (often provided in MCUs) and more > automation as far as the bus dealing with bus-y problems all by itself. > > These might be a little hungry, or overly robust. If you need lower > current consumption, and the signal doesn't have to leave the board, an > open collector bus (like I2C) is still a good idea.
Or you can use CAN controllers in microcontrollers, but with a simple open collector bus. You get the best of all worlds then - a convenient and reliable multi-master bus without much extra hardware (no components at all for your bus, if your microcontroller has flexible enough pin drivers) and with simple software.
> > Tim >
Reply by Jan Panteltje September 24, 20172017-09-24
On a sunny day (Sat, 23 Sep 2017 20:06:06 -0500) it happened "Tim Williams"
<tmoranwms@gmail.com> wrote in <oq70e5$ahe$1@dont-email.me>:

>"Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote in >message news:oq6p70$3dc$1@dont-email.me... >> Tim Williams wrote: >>> >>> And you can, in fact, hack a "routerless" network, using diodes (and >>> much shorter cables, under 20m I think). Collisions are frequent if >>> multiple nodes are talking at once, so it's slow (besides the fact >>> that it may not enumerate higher than 10Mb!). >> >> How can you use diodes to wire-OR the differential pairs, assuming that's >> what you mean? > >Good question -- you use the diode drop to steer to neighbors: >https://electronics.stackexchange.com/questions/10864/building-a-passive-ethernet-hub-with-anti-parallel-diodes > >Tim
That is a very clever circuit, had not seen it before, no power source needed. OTOH economics: I bought 2 good 8 port switches that each came with a power adaptor on ebay for about 12 $ each... To make a PCB, buy diodes and connectors, housing, time.. would be more expensive.
>-- >Seven Transistor Labs, LLC >Electrical Engineering Consultation and Contract Design >Website: http://seventransistorlabs.com > >
Reply by David Lesher September 24, 20172017-09-24
a) We have 2 boards, both Jedi ^H^H^H I2C masters, talking over RS232

b) We use I2C from one board to talk to I2C accessory boards.

c) I wondered "Can we skip 232 and add the other master to the I2C bus?"

Clearly the answer is "stick to what works...."





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