PC archeology: IBM PC XT with a strange appendage

Time for another episode of PC Archeology,. This PC has a strange thing hanging off the back -- what was it for? -- Video Links Support the channel on Patreon:   / adriansdigitalbasement   Adrian's Digital Basement (Main Channel)    / @adriansdigitalbasement   -- Tools Deoxit D5: https://amzn.to/2VvOKy1 http://store.caig.com/s.nl/it.A/id.16... O-Ring Pick Set: (I use these to lift chips off boards) https://amzn.to/3a9x54J Elenco Electronics LP-560 Logic Probe: https://amzn.to/2VrT5lW Hakko FR301 Desoldering Iron: https://amzn.to/2ye6xC0 Rigol DS1054Z Four Channel Oscilloscope: https://www.rigolna.com/products/digi... Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier: https://amzn.to/3adRbuy TL866II Plus Chip Tester and EPROM programmer: (The MiniPro) https://amzn.to/2wG4tlP https://www.aliexpress.com/item/33000... TS100 Soldering Iron: https://amzn.to/2K36dJ5 https://www.ebay.com/itm/TS100-65W-MI... EEVBlog 121GW Multimeter: https://www.eevblog.com/product/121gw/ DSLogic Basic Logic Analyzer: https://amzn.to/2RDSDQw https://www.ebay.com/itm/USB-Logic-DS... Magnetic Screw Holder: https://amzn.to/3b8LOhG https://www.harborfreight.com/4-inch-... Universal ZIP sockets: (clones, used on my ZIF-64 test machine) https://www.ebay.com/itm/14-16-18-20-... RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI) http://www.retrotink.com/ Plato (Clone) Side Cutters: (order five) https://www.ebay.com/itm/1-2-5-10PCS-... Heat Sinks: https://www.aliexpress.com/item/32537... Little squeezy bottles: (available elsewhere too) https://amzn.to/3b8LOOI --- Links My GitHub repository: https://github.com/misterblack1?tab=r... Commodore Computer Club / Vancouver, WA – Portland, OR – PDX Commodore Users Group https://www.commodorecomputerclub.com/ --- Instructional videos My video on damage-free chip removal:    • How to remove chips without damaging the c...   --- Music Intro music and other tracks by: Nathan Divino @itsnathandivino