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.The computerAlmost any popular microcomputer will do; hacking does not callupon enormous reserves of computer power.Nearly everything you hackwill come to you in alphanumeric form, not graphics.The computeryou already have will almost certainly have the essential qualities.However the very cheapest micros, like the ZX81, whilst usable,require much more work on the part of the operator/hacker, and givehim far less in the way of instant facilities.** Page 15(In fact, as the ZX81 doesn't use ASCII internally, but aSinclair-developed variant; you will need a software or firmware fixfor that, before you even think of hooking it up to a modem.)Most professional data services assume the user is viewing on an80-column screen; ideally the hacker's computer should be capable ofdoing that as well, otherwise the display will be full of awkwardline breaks.Terminal emulator software (see below) can some- timesprovide a 'fix'.One or two disc drives are pretty helpful, because you will wantto be able to save the results of your network adventures as quicklyand efficiently as possible.Most terminal emulators use thecomputer's free memory (i.e.all that is not required to support theoperating system and the emulator software itself) as store for thereceived data, but once the buffer is full, you will begin to losethe earliest items.You can, of course, try to save to cassette, butnormally that is a slow and tedious process.An alternative storage method is to save to a printer, printingthe received data stream not only to the computer screen, but also ona dot matrix printer.However, most of the more popular (and cheaper)printers do not work sufficiently fast.You may find you losecharacters at the beginning of each line.Moreover, if you printeverything in real-time, you'll include all your mistakes, falsestarts etc., and in the process use masses of paper.So, if you cansave to disc regularly, you can review each hack afterwards at yourleisure and, using a screen editor or word processor, save or printout only those items of real interest.Serial portsThe computer must have a serial port, either called that or markedRS232C (or its slight variant RS423), or V24, which is the officialdesignator of RS232C used outside the USA, though not often seen onfile:///E|/Books/Hackers Handbook.htm (17 of 133) [11/28/2000 5:58:48 AM] Hacker's Handbookmicros.The very cheapest micros, like the ZX81, Spectrum, VIC20, do nothave RS232C ports, though add-on boards are available.Some of theolder personal computers, like the Apple or the original Pet, werealso originally sold without serial ports, though standard boards areavailable for all of these.You are probably aware that the RS232C standard has a large numberof variants, and that not all computers (or add-on boards) that claimto have a RS232C port can actually talk into a modem.Historically, RS232C/V24 is supposed to cover all aspects ofserial communication, including printers and dumb terminals as wellas computers.The RS232C standard specifies electrical and physicalrequirements.** Page 16Everything is pumped through a 25-pin D-shaped connector, each pinof which has some function in some implementation.But in most cases,nearly all the pins are not used.In practice, only three connectionsare essential for computer to modem communication:Pin 7 signal groundPin 2 characters leaving the computerPin 3 characters arriving at the computerThe remaining connections are for such purposes as feeding powerto an external device, switching the external advice on or off,exchanging status and timing signals, monitoring the state of theline, and so forth.Some computers and their associated firmwarerequire one or other of these status signals to go 'high' or 'low' inparticular circumstances, or the program hangs.Check yourdocumentation if you have trouble [ Pobierz całość w formacie PDF ]