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I think 'easy to write assembly code for them' might be stretching it a little bit. Some instructions were pretty complex and I would expect be quite hard to us
by klelatti 4y ago
I think 'easy to write assembly code for them' might be stretching it a little bit. Some instructions were pretty complex and I would expect be quite hard to use in practice.
What is certainly true is that a single instruction could do a lot, making for much more concise code than would be the case for RISC code.
IBM S/360 is probably the most influential CISC architecture. There is lots of S/360 documentation online. If of interest I did a short post on S/360 assembly a little while ago.
https://thechipletter.substack.com/p/writing-ibm-s360-assembly-by-hand https://thechipletter.substack.com/p/writing-ibm-s360-assemb...
- bogomipz 4y agoThanks but your link has two sentences and then is interrupted by an input box to subscribe to your newsletter and by the time I made it to there my reading was again interrupted, this time by an obnoxious pop up prompt again asking me sign up for the newsletter. Is there a reason to be this aggressive? It's hard to believe this is a successful strategy. If someone enjoys your content they will sign up after they've actually been able read the article. Who signs up for a newsletter before they've even been able to read the first paragraph? I didn't bother with the rest of your link after this.
- klelatti 4y agoThanks for letting me know. It’s a Substack thing not something I’ve chosen to do - I’ve tried to see if I could could turn off all pop-ups in the past without success. I didn’t know it was quite that bad so will have another look and possibly feedback to Substack.
- bogomipz 4y agoSorry I didn't mean to imply that this was your choice. It was a general rant against the sorry state of these platforms that get in the way of the very product they are supposed to be promoting. It sounds like content I would be very interested in. Do you have a blog or somewhere else where this content also lives? Cheers.
- klelatti 4y agoI actually owe you a huge thank you for pointing out how bad the experience was! I genuinely had no idea how awful it was - of course you don't see pop-ups if you are logged in. To be fair to Substack the control to turn off pop-ups was there but it was turned on by default and a bit buried away in the UI. I've removed any mid-article calls to action and turned off pop-ups now so hopefully a much better and less aggressive experience. On the S/360, the article I linked to was a short look at how complex some S/360 instructions were and at how assembly used to be written using pen and paper. If you're interested in more on S/360 Assembly then the principles of operation may be worth a scroll through. [1] Thanks again - really appreciate that you fed back rather than just closing your browser window. [1] http://bitsavers.org/pdf/ibm/360/princOps/A22-6821-0_360PrincOps.pdf http://bitsavers.org/pdf/ibm/360/princOps/A22-6821-0_360Prin...
- flopsamjetsam 4y agoGreat little article. My image of CISC was "complex addressing modes," not something as complex as the EDIT instruction.
- klelatti 4y agoThanks - really appreciate that. S/360 is something else!