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How many x86 instructions?
On 2/23/2014, Yousuf Khan posted:
On 23/02/2014 6:15 PM, BillW50 wrote: On 2/23/2014 4:41 PM, charlie wrote: The front panel on many of the old mainframes and minicomputers allowed direct entry of machine code, and was usually used to manually enter such things as a "bootstrap", or loader program. The way I recall is any computer only understands machine code and nothing else. Anything else must be converted to machine at some point. I know what Charlie is talking about. When he talks about directly entering machine code, it means typing in the binary codes directly, even without niceness of an assembler to translate it partially into English readable. This would be entering numbers into memory directly, like 0x2C, 0x01, 0xFB, etc., etc. Yousuf Khan Not so recently, when I worked on what were then called minicomputers, the boot process went like this: Set the front panel data switches to the bits of the first loader instruction (in machine language, of course) Set the front panel address switches to the first location of the loader Enter the data into memory by pressing the Store button. Set the data switches to the second instruction and the address switches to the second address. Press Store. Repeat a dozen or two times to get the entire bootstrap loader into memory Load the main loader paper tape into the paper tape reader Set the address switches to the starting location of the boot strap loader Press the Go button When to main loader is in, load the paper tape of the program you want to run into the reader Set the starting address to the main loader's first address Press Go That loader will load the final paper tape automatically, thank Silicon Over time the process was streamlined a bit, for example by letting the storage address autoincrement after each Store operation. Maybe you can guess how happy I was when BIOSes started to appear :-) -- Gene E. Bloch (Stumbling Bloch) |
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