Author Topic: Are all serial-/printer-ports equal?  (Read 595 times)

Offline Franky

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Are all serial-/printer-ports equal?
« on: June 01, 2021, 12:44:28 PM »
Hello,
I am currently looking to buy a preferably universally capable Mac for dealing with old hardware via
serial and SCSI-ports, that is able to run apps like alchemy or maybe Emu file assistant and additionally
integrates within a OSX-Macs-filesharing network, or as far as that is even possible.
While according so sites like http://www.applefool.com/se30/ it doesn't look too promising,
at least there are things like SCSI-zip-drives that can carry files between Macs).
Though Dan Knight calls the PowerBook 540 the "ultimate bridge machine"
https://lowendmac.com/2007/vintage-mac-networking-and-file-exchange
I wonder, whether that is really the case, because the G3 PDQ-Powerbook features not only an
ADB- and (Geoport-)serial- as well as a SCSI-port, but is also much more powerful.
But the 540 has a dedicated ('real') serial-port as well as an ADB-port. My question:

Might that make a difference for picky Midi-connections or are all ADB-/Geoport-/'real'-serial-ports
equally usable? For though a Macman Midi-Interface manual states, that it supports
"both the new 9 pin serial GEOport and the old standard 8 pin serial port"
https://www.manualslib.com/manual/569177/M-Audio-Macman.html#manual
someone posted here http://macos9lives.com/smforum/index.php/topic,5957.msg44364.html#msg44364
that "Even the native serial port on the G3 Wallstreet doesn't work".
Could the reason be, that unlike the PB 500-series it (like the PDQ) doesn't have an old
serial-port anymore but only an ADB- plus Geoport-serial interface?
Thanks for your contributions
Franky

Offline robespierre

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Re: Are all serial-/printer-ports equal?
« Reply #1 on: June 02, 2021, 11:01:57 AM »
Hello, Franky.

All of the Macs with built-in serial ports have so-called "real" serial ports, which appear to software as a "Modem" or "Printer" port. A serial port is not a so-called "real" port when it rides over another type of interface such as USB, as is required on Blue+White Power Macs, Bronze/Lombard PowerBooks, or newer machines.

ADB is a different type of interface, not a "serial port" in the conventional sense. It is mostly only used for input devices (mice, keyboards, tablets, etc) and there are no MIDI interfaces I know of that use this port.

AppleShare (file sharing) on older machines used a networking architecture called AppleTalk/LocalTalk/EtherTalk, which is not supported anymore. The file sharing protocol was ported to the TCP/IP architecture in the late 1990s under MacOS 8/9, and can communicate with systems as recent as Catalina. So if you want to share folders from one machine to another, you have to plan carefully. But there are standard Internet file transfer applications for all systems, such as FTP, which overall is more appropriate for transferring samples etc. There are FTP tools for System 6 and it is built in to the latest systems, so no problems there.

As far as choosing between traditional "Zilog 85C30 SCC" ports and GeoPorts, I don't think there is much if any practical difference in compatibility. A GeoPort just has an extra pin for +5V (which isn't used), and a DMA engine (that isn't used). They both support the external 1 MHz clock that comes in from the MIDI interface to set the MIDI transfer rate (1 MHz divided by 32 = 31250 bits per second). More pressing compatibility problems for older software are probably 68k/PPC emulation related.

Offline Franky

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Re: Are all serial-/printer-ports equal?
« Reply #2 on: June 08, 2021, 05:25:47 AM »
Hello,
thank you for the explanation, from which I gather, that all Macs with 'traditional' serial ports should work fine with Midi and that 'serial over firewire/whatever' does not work, at least with old programs (OS9)
So the situation is not as bad as for example this  guide
http://web.archive.org/web/19990428115546/http://www.hinton.demon.co.uk/
alledges, but what do you think:

would a PowerBook G3 (Wallstreet or PDQ) be a reasonable choice for Midi or should it be avoided in favour of a desktop with
a (stealth-) serial port?
Thanks



Offline OS923

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Re: Are all serial-/printer-ports equal?
« Reply #3 on: June 08, 2021, 11:03:54 AM »
I use a Griffin iMate to convert USB to ADB. This works without issues.