5 ms·
Author here. Hopefully you're not all tired of the 8086 by now :-)
by kens 4y ago
Author here. Hopefully you're not all tired of the 8086 by now :-)
- LanternLight83 4y agoCan't speak for everyone, but I'm lovin' it, thanks!
- deleted 4y ago[deleted]
- jacquesm 4y agoNever! I really should get that other chip to you...
- kergonath 4y agoAbsolutely not! I can’t say I understand everything but I love reading your work.
- rwmj 4y agoAre there any physical indications of the order in which instructions were added? I mean to say: Is there any indication that (for example) they added DIV last, perhaps because it's complicated and they didn't know if they could fit that in.
- kens 4y agoAndrew Jenner pointed out that the microcode for the string (block move) operations doesn't exactly match the flowchart in the documentation, and the micro-instructions are kind of scattered around. So it's likely that the string operations were modified late in the process. As far as the other instructions, I haven't seen any particular indication of the order.
- userbinator 4y agoDo you think the 8086/8088 were well-optimised/efficient in general? In other words, had they spent some more effort, could they have reduced the transistor count and reduced the number of cycles the instructions take without changing the functionality?
- kens 4y agoThe 8086/8088 look pretty well-optimized in many ways: the design of the instruction set, the architecture, the microcode, and the silicon layout. Studying it closely, I've seen multiple things that are more clever than I expected, and haven't seen anything that makes me shake my head in dismay.
- bonzini 4y agoJust a note that, just like AAD is a multiplication (and add) in disguise, AAM is an 8-bit unsigned division in disguise and also uses the CORD subroutine.