Digital Circuitry; Microprocessor Circuit - Tektronix 2212 Service Manual

Microprocessor
Circuit
2212 Service Manual
Digital Circuitry
This section contains the descriptions of the circuitry on the A15 processor
board and the A12 frontboard. The A15 board assembly contains the
following circuitry :
- Main microprocessor (Diagram 18)
- Digital acquisition (diagram 16 and 17)
Digital display circuitry (readout, cursors and waveform display)
(diagram 19)
- Parallel interface circuitry (diagram 21)
- Communication options (diagram 22 and 23)
Power connections of the IC's on the A15 board are located on diagram 20A
and 20B. The A12 board assembly contains the following circuitry:
- Front panel switches (diagram 14)
- Front panel LED's (diagram 15)
Diagrams are located in section 9: Diagrams. See also the block diagrams in
this section for an overview of the circuits concerned.
The core of the digital system is a 68070 microprocessor, which basically is a
68000 derivative with build-in peripherals. Of these internal functions the
following are used in the 2212:
- The two channel DMA controller used in the display and acquisition
systems.
- The UART for serial communication (optional).
- I
2
C bus for communication with EEROM on the analog mainboard AlO.
- Timer for several timing tasks.
The 68070 processor (U1801 diagram 18) has a 16 bits databus
(PROD (0 .... 15]) and a 23 bits address bus (PROA
(1.. ..
23]).
Because it uses a 16 bits wide databus, the least significant address line is
Al.
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