On or about 2/4/2009 9:41 PM, James Knott typed the following: > John W Kennedy wrote: >> On Feb 4, 2009, at 7:18 PM, JOE Conner wrote: >>> You are using base ten numbers that are internally represented in >>> base 16 hexadecimal. >> Base 2 binary, actually. Base 16 was historically used by IBM >> mainframes, but they are migrating to base 2 nowadays. (They also >> support base 10, which Intel is unfortunately stalling on.) >> >> Yes, there is a difference between base 16 and base 2. In 1964, IBM >> thought there wasn't. They were wrong. >> > Many early computers, including some from IBM worked in decimal, using a > modified hexadecimal system. One method that was used in an ancient > computer I used to work on was called "excess 6", IIRC. This method used > four flip flops to hold a number, but if you read the binary it was > actually 6 more than the decimal value. This made it easier for the > stage to overflow and pass on the carry bit to the next stage. Setting > one stage to 6, representing 0, was easier than detecting a binary > equivalent of 10 for the carry etc. IIRC, it was IBM's commercial line > that used decimal, whereas the scientific stuff ran binary. > > > >
And don't forget base 12. Base 2, 8, 12, & 16 were very prevalent in the early days. I worked with them all starting in 1959. Sometime it got confusing when the mainframe worked with base 8 or 15 (0ctal or Hexidecimal) and the peripherals were using base 12 (duodecimal). Ed -- All mail is checked by avast! Antivirus Powered by SeaMonkey: http://www.seamonkey-project.org/ The trouble with life is that there's no background music. --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
