Assembly Language Throwdown to Steve by Dave of Microsoft

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M

Mainframe

Guest
Steve should do some Assembler tutorials. I am learning to do some Assembly programming on the Mainframe and seems fairly different than PC Assembly.
 

PHolder

Well-known member
Sep 16, 2020
737
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Ontario, Canada
Well the assembler is just a pretty sugar coating on machine language. Machine language is particular to the architecture of the machine. 6502, for example had exactly three registers (well aside from the program counter) A, X and Y. x86 has been extended a fair bit over the years, and has different modes, the real mode uses a 64k paging design that can be eliminated by later flat (protected) modes. ( https://en.wikipedia.org/wiki/Category:X86_operating_modes ) Motorola 68K has a very regular instruction set where you can use almost any register in any use whereas other architectures have specific uses for specific registers. Then there are the RISC processors which I don't think humans really write code for... they're so unfriendly to use they pretty much require machine generation of code.
 

Duckpaddle

Member
Oct 1, 2020
6
1
I totally agree, that should be his next project after SpinRite! I would love to see what approach Steve would take with teaching ASM. I used Assembler to code for Z80's and CPM. It seemed complicated then but looked back over the code and it seems trivial now. Loved selling customers solutions using CPM 8080 machines for a fraction of the cost of PDP-8s.
 

danlock

Well-known member
Sep 30, 2020
159
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USA
I'm sure there are plenty of Assembly Language resources. What might be harder to find is a cheat-sheet of sorts that lists optimization methods, the ways to do things more easily that Steve mentioned in response to the "throwdown."

[I've never worked for DEC.]
 
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Dave New

Member
Nov 23, 2020
16
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If you get nostalgic for PDP, you can always build one: https://obsolescence.wixsite.com/obsolescence

So far, I've built the PDP-11/70. Lots of fun, and you can see one running behind Leo during the SN podcast.

For that matter, I think those are PDP-8's running behind Steve, as well.

I also have one of these kits: https://adwaterandstir.com/altair/

Unbuilt, so far.

I didn't mess with PDP's much in my youth, but really cut my teeth on 8-bit micros, the 6800, 8080, Z-80, and 6502 on Digital Group systems.

Still have the quick-reference cards for each of those micros, and did write directly in machine code and assembly on each of those platforms.
 

Ralph

Member
Sep 24, 2020
17
3
When I worked for Burroughs (Unisys now days) the B1700 small system used cassettes to load the operating system (MCP) and diagnostics. I worked there from 1975-1982 and worked on a lot of stuff that was old even then. Tape drives, disks, card readers, printers, &c many with no chips, all discrete. Mainframes with core memory (B3500) were old back then, but I learned a lot from that old stuff. Interesting to see how computers have evolved. Someone I knew was going to open a business and was interested in technology. I wanted to make him a 'business card' out of an 80 column punch card but couldn't find a key punch to make it. TIme/ technology marches on. I still have a few bits and pieces of machines from them days.