From: William Levak (wlevak_at_cyberspace.org)
Date: 2002-06-02 20:35:00
I have taken apart a number of Commodore modems to see what is inside.
The results are listed below.
In addition to the model number, the 1660 and 1670 modems have a part
number on the bottom right of the label on the back. In addition the 1660
modems have a name on the circuit board.
The earlier modems are made from discrete parts, standard logic chips, and
a standard modem chip (listed below).
The 1600 modem appears to be a 600 baud modem, but mine isn't working, so
I can't verify that.
The later modems use 2 80C49 microprocessors and what looks like a ROM.
Since these are custom parts, I have listed all the markings on the chips.
It looks like these were made by US Robotics. (A 80C49 is a 8 bit
microprocessor with 128 bytes of RAM, 2K ROM, and 24 quasi bidirectional
I/O lines).
I don't have any information on the 1650 modem. There may also be
310476-03 and 310476-05 versions which I do not have.
If anyone wants to supply the missing information, I will add it to the
list. The modems are held together with four pegs, one in each corner.
They are not glued and can be pried open with a screw driver. It is
easiest to start at the edge connector. WARNING! I pulled the speaker
wares out while opening two of the modems, and had to solder them back.
--------------------------------------------------------------------
Commodore Modems
1600
MC14412 Motorola 0-600 Baud Modem
1660 310476-01 Magic Modem TI-1660
TMS99532 Texas Instruments 300 Baud FSK Modem
1660 310476-06 Magic Modem 1660
MM74HC942N National 300 Baud Modem
1670 310476-02
U6 24 pin USR U100
16-255
8430
U5 40 pin <DKI>
MSM80C49-142RS
JAPAN 46067
U4 40 pin M80C49-206
OKI
JAPAN 48055
1670 310476-04
U4 28 pin (C) USR86
USR101 16-249
SS8839
44764.1
U3 40 pin (C)USR'85
U3J2
OKI C49-388
JAPAN 842018
U2 40 pin (C)USR'85
U2J2
OKI C49-387
JAPAN 842015
with paper label
R/W
14
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