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>"Nice ISA to write assembly code for" was thrown out, or at least demoted significantly." Interesting. Was the guiding principle of CISC ISAs essentially that
by bogomipz 4y ago
>"Nice ISA to write assembly code for" was thrown out, or at least demoted significantly."
Interesting. Was the guiding principle of CISC ISAs essentially that be easy to write assembly code for then? Maybe it's obvious but I had never considered how or where CISC evolved from. Would I have to look at something like the history of the VAX ISA to understand this better?
- klelatti 4y agoI 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!
- pjmlp 4y agoYes, with CISC instructions and powerful macro assemblers like TASM and MASM.