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11A32: Difference between revisions
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The version of the M377 used in the 11A32 has a 100 Ω output impedance per side so that two of them in parallel create a source impedance of 50 Ω per side. | The version of the M377 used in the 11A32 has a 100 Ω output impedance per side so that two of them in parallel create a source impedance of 50 Ω per side. | ||
Each M377 amplifier's nominal common-mode output voltage is zero whether enabled or not. When not enabled, each M377 | Each M377 amplifier's nominal common-mode output voltage is zero whether enabled or not. When not enabled, each M377 differential output is exactly zero by design. This fact is used during calibration by the plugin’s firmware to determine the mainframe’s imbalance and compensate for it during normal operation. | ||
differential output is exactly zero by design. This fact is used during calibration by the plugin’s firmware to | |||
determine the mainframe’s imbalance and compensate for it during normal operation. | |||
Each of the two channels has its own AUX output on dedicated pins of the plug-in interface connector: | Each of the two channels has its own AUX output on dedicated pins of the plug-in interface connector: | ||
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The [[11A34]] and 11A32 were originally intended to use [[Intel 8052]] microcontrollers. | The [[11A34]] and 11A32 were originally intended to use [[Intel 8052]] microcontrollers. | ||
However, during development, the firmware swelled beyond that chip's 8192-byte maximum on-chip | However, during development, the firmware swelled beyond that chip's 8192-byte maximum on-chip | ||
ROM size. [[Doug Haines]] found an alternate supplier of 8051-compatible chips (OKI Semiconductor) | ROM size. [[Doug Haines]] found an alternate supplier of 8051-compatible chips (OKI Semiconductor) that offered a 16 KByte on-chip ROM, and that's what the plug-ins wound up with. The finished code size is about 14 KB. | ||
that offered a | |||
The 11A32 also contains a Dallas Semiconductor DS1220Y NVRAM storing last settings, calibration constants, and instrument serial number. | The 11A32 also contains a Dallas Semiconductor DS1220Y NVRAM storing last settings, calibration constants, and instrument serial number. | ||