My modem does not respond when I use SerialSpeed. What do I do?
First, make sure your modem supports 115Kbps or 230Kbps operation. If
SerialSpeed 230 is set to 230Kbps, try changing the port speed to 115Kbps. This will
fix the problem in many cases.
Note: the Supra Express modem supports 115Kbps operation, but if your Supra Express 33.6 fails to operate at this speed, you have a buggy ROM chip and should get it upgraded. Contact Diamond Multimedia Corp (http://www.diamondmm.com/) for details on this upgrade.
Second, check to see if your hardware and software are compatible with
SerialSpeed 230. See the categories below for more information.
Third, make sure your communication settings are correct.
Fourth, try different software (such as products on the “known working” list. below.)
What Macintosh models are known to work with SerialSpeed 230?
Any Macintosh that can support the GeoPort Modem is compatible with SerialSpeed 230. Here is the most up-to-date list of compatible Macintosh models that we have. Clone models based on these motherboard designs should work also (i.e. Power Computing, SuperMac, Motorola systems)
Macintosh Quadra 660av, 840av
Power Macintosh 4400, 5400, 6400, 6100, 7100, 7200, 7300, 7500, 7600, 8100, 8500, 8600, 9500
Performa 6400
PowerBook 3400
Power Computing Power 1x0, PowerCurve, PowerCenter, PowerTower, PowerBase models
What Macintosh models do not work?
Power Macintosh (Performa) 5200
Power Macintosh (Performa) 6200
PowerBook 190, 2300, 5300 series
The above Power Macintosh and PowerBook computers do not have the
high speed serial ports and cannot use SerialSpeed 230.
If your Macintosh is not a Power Macintosh and is not an “AV” model, it will
not work. Even if you have a PowerMac upgrade board, it will not work. This
is because the upgrade cards do not contain new serial port chips.
What programs are known to fail with SerialSpeed 230?
Older versions of MacPPP (before 2.1SD)
What modems are known to work with SerialSpeed 230?
Practical Peripherals PM288MT II V.34
Hayes Optima 28.8 V.34 V.FC
SupraFAXModem 288/336 only at 115Kbps
Supra Express modem at only 115Kbps
Global Village Platinum at 115Kbps
US Robotics Sportster only at 115Kbps
(almost every V.34 or V.FC modem will work.)
What modems are known to fail?
Any modem that does not support 115Kbps or 230Kbps operation. (this
includes most V.32 and V32bis modems)
Note: the Supra Express 33.6 modem supports 115Kbps operation, but if your Supra Expresss 33.6 fails to operate at this speed, you have a buggy ROM chip and should get it upgraded. Contact Diamond Multimedia Corp (http://www.diamondmm.com/) for details on this upgrade.
Should I install SerialDMA 2.0.2?
Only if you are running System 7.5.2 or earlier system software.
SerialDMA 2.0.2 is included as part of System 7.5.3 and later versions.
The original serial driver for these products suffered from occasional system
hangs, communications timeouts, poor communications performance, and various
other glitches. The new SerialDMA 2.0.2 driver corrects these problems.
Will SerialSpeed 230 work with my GeoPort?
SerialSpeed will not accelerate the GeoPort modems (due to their unique design). For complete details on the GeoPort, see our GeoPort report: http://www.brooklinesw.com/geoport.html
Why won't SerialSpeed 230 work with my SupraFAXModem 288?
It will. But you must use SerialSpeed at 115Kbps, not 230Kbps. This modem
does not support 230Kbps operation.
Will SerialSpeed 230 accelerate programs that use the
Communications Toolbox drivers?
Yes, but make sure you are using SerialDMA 2.0.2 or System 7.5.3, or greater.
What are the limitations of the Printer Port?
Apple documentation states that the printer port is handled at a lower
priority than the modem port (i.e. incoming data is handled first from the
modem port) so high speed operation on the printer port is more risky.
Furthermore, documentation for the Quadra 840AV/660AV states that DMA
operation is not enabled for receiving information on the printer port. In
contrast, Power Macintosh computers have full DMA support on both the
modem and printer ports.
If you have the option, you should use your modem port for high speed
operation instead of your printer port. On the other hand, I have heard many
success stories of individuals who are using their printer ports at 230Kbps
speed every day, with no problems. So it's certainly worth trying.
Can I use SerialSpeed 230 to speed up my serial printer?
Probably not, but it can’t hurt to try. Apple printers and Epson Stylus Color Pro
printers can operate at 230Kbps, but Apple’s serial printers already use
230Kbps serial transfers, so SerialSpeed won’t speed them up any further.
If you have an Epson Stylus Color Pro printer, SerialSpeed 230 may give you
a performance boost.
What is the “DMA Serial Driver” and why do I need it?
Since the first Macintosh, the serial ports have used an interrupt-driven serial
driver. This driver takes valuable CPU time to handle every character that is
received or sent through the serial ports. At high speeds, the interrupt-driven
serial driver gets completely swamped and starts to lose information.
57.6Kbps is about the best you can do with the interrupt-driven serial driver
for bidirectional data transfers (the kind you use with modem programs.) You
can go to 230Kbps in one direction (send) but not receive. That is what the
Apple printer drivers do, because you’re mostly sending data to a printer. But
it won’t work for a modem because you often use it to receive data.
The AppleTalk drivers achieve 230Kbps on all Macintoshes because they
completely take over your computer when they are running, something that
a modem program cannot do. They are “synchronous drivers” as opposed to
the “asynchronous” drivers used by modem programs.
The DMA serial driver makes use of special, improved hardware present on
the “AV” and most Power Macintoshes. This hardware allows information to
flow straight from the serial ports into memory with little or no work on the
CPU’s part. This means that the serial ports can support much higher speeds
in both directions, such as 115Kbps or 230Kbps. Note: The DMA Serial
Driver software is built-in to System 7.5.3 and later releases.
Will they ever release a DMA Serial Driver for my older Mac?
No, because your serial port hardware does not support DMA transfers. The
Mac IIfx does support DMA transfers, but it is unlikely that Apple will
attempt to support this discontinued model in a future software release.
I can force SerialSpeed 230 to load on my older Mac by turning off
the "Check for serial DMA at startup" option. Why shouldn't I do this?
If you happen to have a printer that supports 115Kbps operation or 230Kbps
operation, then SerialSpeed 230 may work to speed up your printer, even if
you have an older Mac.
But for all the reasons stated above, Brookline Software will not provide any
support to users who insist on using SerialSpeed and modems on their older,
non-DMA serial driver Macs. If you try it, it'll appear to work... until you try
receiving large quantities of data. For example, the first time you try a
ZMODEM receive. Then you'll get tons of garbage and the transfer will fail.
My communications software has built-in support for 115Kbps and
230Kbps. Do I need SerialSpeed?
Not for those products. For example, ZTerm 1.0b3 and newer versions of
FreePPP 2.5 have built-in support for these higher speeds. SerialSpeed 230 will
coexist happily with these programs, and won't harm their operation.
SerialSpeed is primarily useful for programs that do not have built-in support
for 230Kbps or 115Kbps operation.
How can I contact the author?
The best way to contact the author is via email;
info@brooklinesw.com. If you need to contact the author via postal
mail, the address is:
Brookline Software
217 East 86th Street, Suite 283
New York, NY 10028
How can I get the latest version of SerialSpeed 230?
New versions are always sent to major Macintosh FTP sites, including INFO-MAC (sumex.aim.stanford.edu). Copies are also available on AOL, CompuServe, and on
the Brookline Software web site: http://www.brooklinesw.com/
