Re: ADTPro 1.1.4 released

[Hugh Hood <hughhood@earthlink.net>]

Guys,

I'm not sure I'd beat myself up too badly if you're unable consistently to
achieve 115,200 baud with the _built-in_ serial ports on the Beige PowerMac
G3, particularly under Mac OS X.

I've found that the built-in ports on that machine (both Printer and Modem),
which are driven by a _clone_ of the Zilog 8530 (rather than by the real
McCoy 8530 as found on the Apple IIGS), are inferior in some respects.

For example:

(i) the industry standard ATEN serial-to-parallel converters, which work
flawlessly with the Apple IIGS built-in serial ports, fail when used on the
PowerMac G3 built-in serial ports, apparently due to a difference in
electrical signal levels.

(ii) I was _never_ able to communicate at 115,200 baud with the PowerMac G3
built-in serial ports, even under Mac OS 9 and ProTERM Mac. Moreover, OS X
support for the built-in serial ports on the Beige PowerMac G3 using the
kernel extension from Apple never allowed me to achieve 115,200 baud. The
maximum rate I ever got was 57,600 baud. Obviously, since OS X 10.2 (Jaguar)
was the last official version to support the Beige PowerMac G3, Apple really
had no reason to update or improve the built-in serial driver when 10.3
(Jaguar) appeared.

Conversely, I _do_ achieve 115,200 baud without issue when using any of the
PowerMac G3 and PowerMac G4 models with a Keyspan PCI slot serial card and
using _Keyspan's_ driver for that card. In that sense, the Keyspan card
'upgrades' the performance of the PowerMacs to the same level as that which
I've come to expect from my Apple IIGS's. <grin>

I've also got a couple of Keyspan USB-Serial adapters, but I've never tried
them to see how high they'll max out.

Buy, hey, if you and David get that Beige G3 solid at 115,200 baud with the
built-in ports, I'd love to hear about it.

Hugh Hood...



in article dog_cow-1264633734@macgui.com, D Finnigan at dog_cow@macgui.com
wrote on 1/27/10 5:09 PM:

> schmidtd wrote:
>> 
>> If I didn't know better, I'd say it was the cable - I've seen things
>> quit right at the file-query stage when there was a problem with
>> handshaking lines.  But you said you had success initially.
> 
> Yes.
> 
>>  What's
>> your cable's pinout?
> 
> I don't know. It's a cable which usually connects the ImageWriter II to the
> IIgs, so I suppose it's a standard printer cable. I don't usually use it for
> communications, but it was handy so I pulled it out of the box.
> 
>> How are you connected to the G3?  I assume it's
>> a USB adapter - which one/chipset is it?
>> 
> 
> I am fortunate to have a desktop G3 which has ADB, SCSI, serial ports, a PCI
> USB card, etc. So I just use the printer port. But I also tried switching to
> modem port-- no luck either.
> 
> Here's a photo of the back of my G3 for reference:
> http://macgui.com/upload/gallery/f_0/user_2/regular/upload_1096.jpg