Early
Electronic
Calculator		 Wang 520 Calculator

Manufacturer: Wang
Model: 520
Year: 1972
Form: Desktop
Functions: Scientific, programmable, tape storage, printer.
Number of Digits: 11, 11E2
Display Type: NIX
Display:Wang 340-0011
Display:Wang 340-0010
Logic Technology: SSI,MSI
Memory Technology: LSI
Diodes: 2469
Transistors: 98
Principal ICs: 7400 TTL Series (219 total)
Tech. Data Level: 2
Tech. Data Source: MF
Tech. Data Pages: 21
Tech. Data:offline

Notes:
  • Store/Recall Register-N function keys operate by pressing a numeral-pad key (not a register 0-15 key) after the Store/Recall key. Decimal-point, Clear-display, Set-exp keys, etc., are used for registers >9.

- Unit Log -

Serial Number: BB 1046
Year of Manufacture: 1972 (Board stamped with 31 January 1972)
Date of Receipt: 21 Sep 2003
Source: SPARC contact.
State upon Receipt: Received as 3 parts, main chassis, ROM board and keyboard. Missing case, printer and tape drive. -12V regulator transistor dented. ROM has at least one broken wire. Complete model number is 520-14-T-P. Also marked with Canada Agriculture 128516.

Date: 29 Sep 2003
Procedure: Dusted off, parts connected together to test basic functionality.

Date: 29 Sep 2003
Procedure: Power supply tested with all logic boards removed, all seems OK. Dented -12V regulator transistor (2N1540) replaced with ES21 (PNP-Ge). Upon power-up with everything connected, multiplexed display was active, but unresponsive to keyboard. After a minute, with switches set properly, unit was functional as regards basic operations.

Date: 05 Mar 2005
Procedure: Keyboar panel cleaned. Peeling sticker on keyboard removed ("Ensure Printer is OFF before switching Wang ON or OFF").

Date: 05 Mar 2005
Procedure: Redrawing of diagrams from Wang schematic largely complete. Exercises performed to figure out functioning.

Date: 11 Mar 2005
Symptoms: Program storage from locations 952 to 1463 (inclusive) have "4" bit stuck on.
Analysis: MK4008 memory chips for bit 4 moved around to confirm bad chip and to map memory. Chip in location 213 has 4 pins (16,15,14,11) rotted off.
Solution: New pins soldered on to IC (ceramic package).

Date: 25 Mar 2005
Procedure: Core Rope ROM interface constructed and program written to examine ROM via SWTP M6800 computer. Contents of ROM read successfully, except for a few locations which present inconsistent data.

Date: 26 Mar 2005
Symptoms: Search function and f(x) (which presumably uses search) do not function.
Solution: Broken wire on core ROM board at address 1260 (octal) spliced.


  Wang 520
Calculators | Integrated Circuits | Displays | Simulations
EEC 		bhilpert