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Folklore has variations on explanation, but two popular explanations are a) IBM used posedge IRQ in some of their “real” computers, and was used to it, or b) It saved half a dual D-flop for some onboard device.Ģ) Since this prevents (or rather, is believed to…) sharing of interrupt pins, all device drivers code their handlers as purely stand-alone, no concept of a general IRQ handler, circa 1960s or maybe older, or even a chain of “handlers that may be interested in this pin, please re-check when you are done”ģ) Some bright spark figures out that the IRQ pins can be shared, possibly by using a negative blip on a normally high line, with a polite set of IRQ handlers.Ĥ) Alas, once again the “hardware” is allegedly so-called because it’s hard to change, while the “software” is so called because it’s easily changed. #PRINTER DRIVERS FOR WORDSTAR 7 PC#What I recall of the IBM-PC IRQ fiasco was a bit of a chicken and egg.ġ) Original PC uses positive-edge-triggered IRQ. There were several aspects to Musical Boards:ģ, Get the system to drop the assigned IRQ for that boardĤ, Get the next board in guaranteeing an IRQ clashĥ, Put the boards in the proper order so the system would reassign the clashed IRQs in the system table in the order needed.īetween each step was a reboot and a lot of humming. It became a game of musical slots and boards to get all the device IRQs assigned to the proper boards. Except, not every device could use the table auto-assigned IRQ. Then came Plug and Pray and in theory, the system would auto-assign the IRQ from an internal table of open IRQs. So when installing you had to start with a big Venn diagram of IRQs. When there were just pin jumpers, it was not too difficult except where the device makers only offered a few IRQ options that were mutually exclusive to something else that was also needed. #PRINTER DRIVERS FOR WORDSTAR 7 INSTALL#The bus had only N IRQ addresses and often there was a need to install N+1 devices in the slots. Re: Plug and Pray with the IRQ Pin Jumpers I still follow “work flows” as it makes security rather easier to manage as a system guardian, and a lot harder to attack by both outsiders and insiders as it limits their scope at each stage. Walk down any town high street and what do you see? Yup people glued to their mobile phones etc, not looking where they are going, or even hearing the curses and bad words sent in their directions because they are immersed in their tunes etc …Įvolution has taught us the hard way there is good reason for “work flows” as they tend to improve our survival chances significantly… ![]() Whilst it might be nice to have a toaster to heat “pop-tarts” do we realy need one that also makes Strawberry Pavlov as just one of a myriad of overly refined carbohydrate comestables to rot our teeth, bodies and brains with, whilst turning us into push button simpletons getting the next quick fix / sugar high? That not only do they come with their own inbuilt programming languages, they also have inadvertant Turing Complete state machines acting as other hidden languages… Now it all get’s thrown into one “mega-app” we call a “Word-Processor” with so much redundancy, over complexity bells and whistles. Even less remember the early “Type-Setting” which still lurk around *nix man pages. If you think about traditional work flows such as writing a book or producing any other major work tgings were done in an order of increasing complexity.įew remember basic text editors as the only way to get human endevor into a computer. One of the things we forget is that “What You See Is What You Get”(WYSIWYG) is very much responsible for many many of our “computing ills”. The point is though, if you make something “easy to use” then it “hides complexity” and it is the complexity where the daemons get corrupted into demons and complexity is the place,where they hide out and play nasty with your system. ![]() IBM simply copied the idea in the PC because it was so successful, sitting on the sidelines in both cases was however Microsoft with their Hardware (yes few remember Microsoft were a hardware company back then).īut yes Microsoft founded what some called “Plug and Pray” as “The Microsoft Way”. #PRINTER DRIVERS FOR WORDSTAR 7 SERIAL#It goes back to the start of “Open Hardware Standards” and non CPU specific BUS standards for the likes of interchangable/removable and non-local peripherals, like serial terminals, modems, tape drives, floppy drives.Īpple took the idea of I/O bus into the heart of the CPU box, and added ROM support to hook into the BIOS. Historically you can blaim the hardware designer’s, of I/O devices of which I’m guilty of being one. Let’s place the blame on where it should be, One Microsoft Way. ![]()
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