Manufacturer: Hewlett-Packard Model: 2116C Serial No.: 1047A00183 Year of Manufacture: Most component date stamps are from 1969 to 1971, HST interface 1976. Other ID: Also labeled with WTY 1111-A.   Received: September 2003 Source: Thru SPARC. State upon Receipt: Dusty dirt from storage, some spot corrosion on open aluminum surfaces, some scratches on cast frames and upper grey front panel, otherwise good condition. Missing key for front cover and power cord.

Repairs:

Oct 2003	(H):	Front panel lock drilled out due to lack of key. Exterior panels, power supply regulator modules, boards removed for dusting.
03 Nov 2003	(H):	Powered up with most boards in. Front panel operational. Problem with some memory locations. The first 64 words on each half-page (512-word) boundary are not accessible. (Appears they may be readable but not writable.)
04 Nov 2003	(H):	Front panel lock cylinder cover installed.
04 Nov 2003	(H):	HALT, A14 and M15 lamps are burned out. Parity Halt lamp moved to A14.
04 Nov 2003	(H):	Broken lower lever on INHIBIT board replaced.
04 Nov 2003	(S):	Simple test programs (incrementing loop, walking bit display) manually loaded and successfully executed.
18 Nov 2003	(H):	With X/Y driver board reverse-engineered, memory problem traced to bad transistor in driver BR2b-. BC junction reads at almost double 'resistance' than equivalent junctions of other drivers. With the pins disconnected, both junctions read open.
22 Nov 2003	(H):	X/Y driver board transistor for driver BR2b- replaced with 2N2219. 8K memory now fully functional.
10 Apr 2004	(S):	Assembler and disassembler written.
01 May 2004	(S):	Simulator written.
05 May 2004	(H):	Top and bottom panels cleaned, bottom and back structure wiped down.
05 May 2004	(H):	Original mil-spec power connector (Amphenol MS3102 A? 22-9P) removed, replaced with wired-in power cable.
05 May 2004	(S):	Time-Base Generator successfully tested with busy-wait program.
06 May 2004	(S):	HST interface successfully tested with busy-wait input and output programs.
07 May 2004	(H):	Side and back panels cleaned.
07 May 2004	(S):	PFR loader routine successfully executed. Initial problem with data overrun when data sent to the HST/loader has only one stop bit (even though HST interface is strapped for one stop bit). Runs successfully when data is sent with two stop bits.
07 May 2004	(S):	HST interface successfully tested with interrupt-based I/O programs and combined interrupt-based Time-Base Generator / HST interface program.
10 May 2004	(S):	First version of monitor (memory commands) successfully tested.
14 May 2004	(S):	7970A Tape drive exercised via monitor commands.
18 May 2004	(S):	Data (3 files) recovered from the 'Mag Tape System' tape (the one tape that came with the drive). The first couple of records of the first file had parity errors.
27 May 2004	(S):	Version 2 of monitor installed.
27 May 2004	(S):	HST properties examined to determine why it doesn't receive properly when sent characters with a single stop bit. Problem traced to busy flag remaining high through end of first stop bit and into following start bit.
28 May 2004	(S):	HST jumpered and tested at 9600 and 19,200 BPS. Successful.
29 May 2004	(S):	Problems with tape I/O, most commands work but any commands involving data transfer fail to terminate (command channel flag is not being set). Problem suggests an absence of read clock from the drive to the controller.
30 May 2004	(S):	Tape I/O problem seems to have gone away, perhaps as a result of rearrangement of equipment and cabling.
31 May 2004	(S):	Instruction rate tests performed, establishing basic memory cycle time and instruction period for single-memory-reference instructions at 1.6µS, the same as HP documentation specifies for the HP2116B. Two tests were implemented by counting loops of 8 instructions and 1000 instructions over 1 and/or 10 second intervals.
07 Jul 2004	(H):	Overflow lamp burned out. Indirect lamp moved to Overflow.
07 Jul 2004	(S):	New version of NSOM using DMA for mag tape tested. Problem with count of words transferred. Traced to lack of upper two bits of DMA length register, resulting in subtraction calculations being incorrect.
29 Sep 2005	(H):	Heatsink modules removed, compressed nuts re-tapped so screws don't bind. Screw hole for A301 drilled out for better fit.
29 Sep 2005	(H):	16V zener (2184) on A301 blown while measuring voltages (shorted from +12 to case/base of 2N1304. Replaced with MZ1000-19 (17V, measures at 16.8V). Shutdown tested by opening new zener, still functions, so transistor and IC input are OK.
30 Sep 2005	(H):	Power supply diagram / reverse engineering completed.
May/Jun 2013	(E):	Powered up. Blinken program runs after a memory correction. - MonitorV2 shows boot message but displays 'interrupt at 11' repeatedly after being started at 000100. - BBL has numerous memory errors. Re-toggled. - MonitorV2 reloaded via BBL, runs.
24 Sep 2014	(E):	Powered up. Blinken (017100) and Monitor (002000) run.
24 Sep 2014	(H):	New CM345 bulbs inserted in HALT switch, M15, INDIR, INTERRUPT & 2 SPAREs.