I've been sort of a computer history enthusiast lately. Read about 7 books in the last few months. I found this read very interesting. Always wondered how these where built inside.
SLT is an interesting technology since it falls in between discrete transistors and integrated circuits. IBM's SLT hybrid modules were metal packages 12mm on a side. Inside a module they put a few separate semiconductor dies (transistors and diodes) and precision-trimmed thick-film resistors on a tiny circuit board. It's like an integrated circuit on the outside but separate components on the inside.
For a while, IBM built SMS cards that used SLT modules in place of the discrete resistors and diodes. They needed to keep the discrete germanium transistors though because the SLT modules were silicon-based. A picture of one of these SMS cards is here: http://righto.com/sms/DGW.html The result is extremely space-inefficient, but it was a cheaper way of building backwards-compatible cards.
For a while, IBM built SMS cards that used SLT modules in place of the discrete resistors and diodes. They needed to keep the discrete germanium transistors though because the SLT modules were silicon-based. A picture of one of these SMS cards is here: http://righto.com/sms/DGW.html The result is extremely space-inefficient, but it was a cheaper way of building backwards-compatible cards.