AMR Modem Riser » History » Version 3
laforge, 12/28/2021 07:28 AM
1 | 1 | laforge | {{>toc}} |
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3 | h1. AMR Modem Riser |
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5 | AMR (Audio/Modem Riser) cards were used towards the end of the "modem days" where the actual analog modem was completley implemented in software, interconnected via a kind of sound card to a telephone jack. |
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7 | In certain generations of PCs, the mainboard contained an AC-Link interface to which external codec ICs (ADC/DAC) are attached. To avoid mainboards having to include the [expensive, space-consuming] line interface circuitry on-board, the AMR connector was defined by Intel. This way the AC97 modem codec IC and analog line interface was pushed to an extension card. |
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9 | See the AMR specification attached in attachment:amr.pdf for details on the AMR form-factor, as well as attachment:ac97_r23.pdf for the AC97 specification covering the AC-Link interface. |
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11 | h3. AMR mechanical connector |
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13 | The mechanical connector is a TE connectivity 5650090-7 PCB edge connector: |
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15 | !5650090-7_sml.jpg! |
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17 | h2. AZTECH MR2800-W |
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19 | 2 | laforge | This is an example of an AC97 codec based modem implemented in the AMR form-factor. |
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21 | The original user manual can be found in attachment:aztech_mr2800w_amr_modem.pdf |
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23 | In 2021, it is available for purchase as a low-cost surplus part from Pollin at https://www.pollin.de/p/amr-modem-aztech-mr2800-w-platine-mit-2a-relais-2-wechsler-700509 |
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24 | 1 | laforge | |
25 | !I700509.3-AMR-Modem-AZTECH-MR2800-W-Platine-mit-2A-Relais-2-Wechsler.jpg! |
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27 | h3. Si3014 + HAMR5603 DAA chipset |
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29 | As can be seen on the picture, it consists of a combination of Si3014 and HAMR5603. The data sheet for the Si3014 is available, but for the HAMR5603 we couldn't find it so far. |
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31 | It seems like originally the Si3014 was supposed to be paired with a Si3024 (the combination being called Si3038), see attachment:si3038_si3014_si3024_softmodem_ac97.pdf |
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32 | 3 | laforge | |
33 | h2. Talking to AMR modems in 2021 |
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35 | There is some work ongoing to create a break-out board (#5294) and an iCE40 based AC97-to-USB adapter, with the idea being to use those AMR cards as low-cost analog phone ADC/DAC interface for playing with [[linmodem:]] |