We ancient fossils fondly remember the "IBM System/360 Reference Data" (X20-1703), better known as the green card ... a 12-panel folded document that summarized the instructions, mnemonics, operands, and hardware data structures of the original IBM S/360. The appearance of a green card in a shirt pocket – likely behind a pocket protector full of pens – identified the bearer as a true believer ... a programmer not to be trifled with. Over the decades as the architecture grew from 151 instructions to well over 1,200 in the current z/Architecture models, the green card grew into a reference-summary booklet (of varying colors) that now exceeds 100 pages.
In this century, IBM eschewed hard copies by (a) providing these documents in a PDF for free, and (b) charging outrageous prices prices for hard copy; then about 10 years ago, they dropped hard copy completely. For the PoO, this was understandable ... it now consumes over two reams of paper and costs a bundle to ship. However, for the Reference Summary, this made the publication MUCH less useful. (I have actually printed a copy, trimmed it down to size, taken it to Kinko's for comb binding, and never looked at it again. ) Since all of the information in the Reference Summary can be found in the PoO – and it seems unlikely that IBM will come to their senses and make hard copy again – it seems ridiculous to bother producing it any more. I asked the current editor of the documents his opinion, and he agreed that it's unlikely that the Reference Summary is useful any more. This seemed like a great forum to solicit informed opinions. However I do hesitate, knowing that some will take this as an opportunity to vent their spleen about documentation in general. Please don't. I simply wish to provide feedback to the Systems Architecture group as to whether this document is used in its current online-only format.
