Why blinkenlights ?

Jos Dreesen wrote: Direct access to the memory and CPU without any interceding translation? It was the simplest and best known. And it was easy to adapt to and use. And it was easy to debug or modify. Mainframe legacy (habit?). And simple. And inexpensive. And cool. EPROMS did not exist (or were very unavailable) in the beginning and then were far more expensive than a handful of switches and lights. And specialty keyboards like those on the H8 also did not exist "In The Beginning" and they required additional interface circuitry. 7-segment LED's were also very expensive--once they were invented and other display devices were cumbersome, expensive or required additional circuitry. But I think that fuse PROMs were used before EPROM's for loading bootstraps. Programming (E)PROMs was expensive, above and beyond their high prices, and took time. And one had to beware of the rip-off programmers that took money for doing nothing, burning the wrong code, damaging the device, taking your new device and giving you their broken one, keeping the device and your money, or not burning it at all. Programming gear was very expensive, well out of hobby range. (E)PROMs were more valuable than gold or diamonds when they first came out and less forgiving of errors. (In the case of PROMs, mistakes were permanent .) Panel switches allowed one to fix mistakes more or less instantly for free. PROMS, you tossed them. EPROMSs, you sent them back to figure out whether they broke, were programmed wrong or the program you provided was wrong then paid to reprogram them and waited. The first micros use incandescent lamps such as "grain-o-wheats" in panel inserts. There were lamps designed specifically for use in computer panels and were common in minis. $50 would more than cover the switches and lamps for a front panel, IIRC. Far less pricey than building a binary-7seg converter for incandescent or a nixie driver at the time. There were indicators and single-digit displays available as well but they were expensive. More expensive than 32 or so single lamps or LEDs. Besides, they wouldn't look as cool. Data General took the switches and lamps off their Nova front panels and put on just a three-position rocker or paddle switch and booted from PROM. Looked desolate and naked. Not at all like a Real Computer. And if it was actually running--well it wasn't telling; only if there was output could you tell. That's when someone else invented boot prompts & messages. -- jd Comparing information and knowledge is like asking whether the fatness of a pig is more or less green than the designated hitter rule." -- David Guaspari