barmar@think.com (Barry Margolin) (11/10/90)
In article <403@bally.Bally.COM> siva@bally.UUCP (Siva Chelliah) writes: >Q: If you have just the hardware, how would you feed the machine language > into the computer ? >A: I thing you should burn the machine language into a chip, that would > accept a machine language from the user, and execute it. Ah, how soon they forget: front panels! In high school (I graduated 11 years ago) we had a PDP-8 minicomputer, which contained no bootstrap ROM. When powering it up, we had to feed in a short (around ten instructions) program by manually flipping the front-panel switches. This program was called the Read-In Mode (RIM) Loader, and it was a simple loop that read bytes from paper tape reader into consecutive memory locations, and was used to read a short tape containing the BIN Loader, which was then run to read in the OS tape. However, the above answer is correct for most modern computers. There's generally a ROM or PROM that contains code that knows how to talk to the console and read the OS from a disk, and often also contains diagnostics that can be run without the OS (for instance, to tell you why it's having trouble talking to the disk). I've redirected followups to comp.misc, as this no longer has anything to do with C. -- Barry Margolin, Thinking Machines Corp. barmar@think.com {uunet,harvard}!think!barmar
alanj@nevermore.WV.TEK.COM (Alan Jeddeloh;685-2991;61-201;292-9740;orca) (11/13/90)
In article <1990Nov9.174222.18666@Think.COM> barmar@think.com (Barry Margolin) writes: >Ah, how soon they forget: front panels! > > <description of booting the PDP-8> And don't forget the back panels. Anyone remember the venerable CDC 6000 ? The mainframe had a matrix of N (12 <= N <= 32)(?) X 12 toggle switches. Big ones -- the whole array being about 18 inches X 24 inches. Each rom was one 12-bit Peripheral Processor instruction. Into those switches you entered the bootstrap code for the first PP. What I would call a bootstrap MWROM -- Manually-Writable Read-Only Memory! -Alan Jeddeloh (503) 685-2991 Tektronix Network (Yes, we're still here) Displays D/S 60-180; PO Box 1000; Wilsonville, OR 97070 alanj@nevermore.wv.tek.com Quoth the printer, "Nevermore!"