This TDS784D  is in good  condition and has options 13, 1F, HD, 2F, 2M. It passes all self testing, self calibration, and functional checks. 

Some options are defined here: 

Tektronix DPO Oscilloscope per TDS operator manual

Model TDS784D

Includes the following options:

13 - RS232/Centronics Hardcopy Interfaces

1F - Floppy Disc Drive

HD - Internal Hard Disc Drive

2M - Add'l 2M/Channel Memory Length

2F - Extended Waveform Math

2C - Communications Signal Analyzer

3C - P6701B with system calibration

Oscilloscope comes with a P6701B and calibrated short-wavelength optical reference

receiver on channel 1. (Option applies to TDS 500D & TDS 700D only, except TDS 794D.)

4C - Fibre Channel Optical Reference

Highlights:

1 GHz Bandwidth, 4 Channels

• Sample Rates to 4 GS/s
• Record Lengths to 8 M Points
• Up to 200,000 Waveforms per Second
• 8-Bit Vertical Resolution, >11 Bits with Averaging and >13 Bits with Hi-res
• 1 ns Peak Detect
• Floppy Disk Storage
• Iomega Zip and Zip Plus Drive Compatible
• Advanced Triggering
• 29 Automatic Measurements and Measurement Statistics
• FFT, Advanced Math, Histograms, Limit Test
• FastFrame Time Stamp
• Communication Signal Analysis, Including Mask Testing and SONET/SDH and Fibre Channel Optical Reference Receivers
• GPIB