IBM Model 5160: Part 10 (640KB Conversion & Portable PC Keyboard Converter)
14Inspired by @Epictronics1 video where he converted a 256KB board to 640KB, I decided to do my PC/XT (Model 5160) and Portable PC (Model 5155) as well ... I do the 5160 in this video.
Roman's video:
https://youtu.be/F_AFgeEWewE?si=bkzyBY5XM7EiaBZ6
Documentation:
https://www.minuszerodegrees.net/5160/motherboard/5160_upgrading_256k_motherboard_to_640k.pdf
I sourced my 256kbit chips (Siemens 41256-12) from Unicorn Electronics in the US - not an ad, I just trust them compared to random Chinese sellers on Aliexpress.
https://www.unicornelectronics.com/IC/DYNAMIC.html
I also encounter an issue with my Model F keyboard ... it'll stop working shortly after booting. To identify where the issue might be ... keyboard or computer ... I use my Portable PC's keyboard.
It can't be used directly as it has an RJ12 plug, so I make an RJ12-to-DIN cable ... and it works. Thus it looks like my keyboard is the issue. That'll be another video.
For my converter plug, I used an RJ45 joiner (two RJ45 sockets) and an RJ12 cable with four conductors (pins 2-5, pins 1 & 6 on the outside edges not wired). The RJ12 pin numbering is from left-to-right looking at the plug with the clip on top.
DIN p1 = RJ12 p4 = clock
DIN p2 = RJ12 p5 = data
DIN p3 = not used
DIN p4 = RJ12 p3 = ground
DIN p5 = RJ12 p2 = +5V
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