11300
Internals Common to the 11301 and 11302
In this section, "11300" refers to the 11301 and 11302.
The 11300 is a digitally controlled analog oscilloscope. Like a typical analog scope, the 11300 has vertical amplifiers, a trigger circuit, a timebase/sweep, a horizontal amplifier, and a CRT. Unlike traditional analog scopes, an 11300 system contains contains a significant amount of digital circuitry, including multiple microprocessors, one in the mainframe and at least one in each plug-in. The digital circuitry provides several externally-observable features:
- self-test and diagnosis
- self-calibration
- remote control via RS-232 or GPIB
- on-screen menu-based touch screen user interface
Digital circuitry also implements some features that were traditionally implemented with analog circuitry, e.g., the trigger holdoff is implemented with a counter instead of with a multivibrator.
There are many DAC-generated analog control voltages in the 11300. These are produced by the Analog Control Voltage System.
The left and center plug-in can be used as the vertical axis and/or the trigger signal. The right plug-in can used as the horizontal axis and/or the trigger signal.
The RS-232 interface of the 11301 is implemented using an 8251A UART chip, interfaced using an MC1488 line drive and an MC1489 line receiver.
The mainframe communicates with the plug-ins via the Serial Data Interface (SDI), which is part of the 11000-series plug-in interface.
The 11300 performs a variety of self-checks and self-calibration. Some of the self-checks are digital in nature, e.g., testing RAM by writing a pattern, reading it back, and comparing what was read with what was written. Other tests are analog in nature. For the analog tests, there is an analog bus, ABUS, that allows various voltages throughout the scope to be measured by the test routine. The ABUS is a fan-in tree formed by 74HC4051 analog multiplexers. One level of multiplexing happens at the module level. The ABUS signals from each of the modules are brought to the main ABUS multiplexer (lower left corner of schematic drawing 12, Partial A11 Main Processor Board). The output of the main ABUS multiplexer is fed to an LF398 sample and hold IC, the output of which is fed to an AD574 12-bit successive approximation analog to digital converter.
The 11300 has a GPIB interface implemented using a TMS9914A GPIB controller IC.
The 11300 uses a TMS4500A DRAM controller to manage a bank of 41464 DRAM chips.
The main CPU in the 11300 mainframe is an Intel 80186. Program memory for the 80186, i.e., firmware, is stored on eight 27512 EPROMs. Four of the EPROMs contain the lower bytes and the other four EPROMs contain the upper bytes. This is shown on schematic figure 9, Kernel.
The 11300 has a real-time clock powered by a 3V lithium battery. The real-time clock is a 6242 IC.
The A sweep and B sweep are each generated by 155-0240-00 ICs.
The vertical amplifier in 11300 mainframes is U520, an H2053 hybrid with part number 165-2053-00.
Full calibration of an 11301 requires the use of the TEKCATS software.
Calibration constants are stored in an Intel D2817A EEPROM.
The 11300 scopes have a counter/timer IC, Tektronix part number 230-0022-50. The die is M229.