Motorola SM56

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By: Bradford W. Liedel

The Motorola SM-56 is another Host Signal Processing (HSP) chipset based modem. The lack of a Digital Signal Processor (DSP) or control chip yet again hitting the modem market with a nasty blow. The modems will connect, and you will get the same speeds as other modems, however the lack of the DSP cuts into your computer's processor, and instead of the modem running off of it's own internal instructions, it largely runs off of software on your computer. Due to this, as always, it is HIGHLY RECOMMENDED that one of the major steps that you take in getting these modems to connect is to get the latest software for the modem.

I have yet to find a basic procedure for getting these modems to work, as I have not dealt with them quite as much as I have certain other brands. They are tricky, but any connection troubles you experience with them can be fixed. One of the main things I have noticed about Motorola SM-56's when connecting to USR Total Controls is that they often connect at v.34 and have frequent dropped connections. It may be, perhaps, that the Motorola SM-56's are more sensitive to line noise, or that they were just getting poor connects and eventually dropped due to this. Here is the procedure I would use:

Fifos: You cannot change the fifo settings on an SM-56.

Inits: First lower the port speed to 57600

AT&F&C1&D2*mm14 (Basic connection trouble solving init + disable k56flex)

AT&F&C1&D2\KS10=200S15=125 (Basic connection trouble solving init + not a clue)

AT&F&C1&D2*mm15 (Basic connection trouble solving init + disable k56flex)

ATZ (Basic init)

AT&F (Basic init #2)

AT&F%B18 (Set connection speed to 33600)

AT&F&C1&D2 (Basic connection trouble solving init)

Three very important strings to remember when dealing with an SM56 are *mm15(disable kflex), *mm14(disable kflex), *mm13(disable v90), and *mm12(force v34).

Other things to try: If dropped connections are a problem, try checking the box that says required to connect under error control. A newer thing we have been trying on the Lucent modems which is an odd fix, but works is switching RTS/CTS (Hardware flow control) to XON/XOFF (Software flow control). I think this fix might also work for these modems. If drop connects are not the problem then you may want to try (as a last ditch effort) turning error control OFF.

Other things to note: The minimum system requirements are as follows:

The SM56 ISA:

150MHz Pentiumョ Processor
w/256K L2 cache

The SM56 PCI:

150MHz Pentiumョ Processor
233MHz AMD K6/K6-K6-2 Processor
266MHz Cyrix 6x86MX Processor
256K L2 cache
Windowsョ 95/98 with 16 Mbytes RAM
Windowsョ NT 4.0 with 32 Mbytes RAM

The SM56 AC-L:

233MHz Pentiumョ II Processor with 256K L2 cache
266MHz Celeron Processor
AC-Link V.2.1 Compatible Core Logic chipsets
Windowsョ 95/98 with 16 Mbytes RAM
Windowsョ NT 4.0/2000 with 32 Mbytes RAM
8 Mbytes free hard disk space One AMR/MDC slot

Here is a partial list of manufacturer websites who make modems with the SM56 chipset: