There was the so called “packed BCD” format, where every byte stores two decimal digits. This is usefull for fixed-point decimal arithmetic which in turn is important for financial arithmetics. 32-bit float as used back then were much to imprecise to be used for even simple financial stuff. So the BCD mode had it’s use because it made this much faster.
@thelleht it would have been useful if you were working on a 6502 built in a calculator that went 6502 -> bcd decoder -> 7seg or the such. For a normal desktop computer I can’t see it ever being useful either, I agree.
@ianhan79 There were BCD instructions in the 68000 too. Can honestly say I literally NEVER used them. I read they even took them out of later versions of the 680×0 series.
@mercatormac Aha. Cool, thanks. I didn’t see it the first time.
@Psychlist1972 6:51 It appears at the top left of the screen, because the code writes to the memory addresses directly.
In the presentation, WAIT 6502,1 didn’t appear to do anything. I thought it printed “MICROSOFT” on the screen?
@frother Looks like Apple Keynote
Does anyone know what presentation program that is?It doesn’t feel like powerpoint
Little-endian. The correct endian-ness, as everyone knows.
There was the so called “packed BCD” format, where every byte stores two decimal digits. This is usefull for fixed-point decimal arithmetic which in turn is important for financial arithmetics. 32-bit float as used back then were much to imprecise to be used for even simple financial stuff. So the BCD mode had it’s use because it made this much faster.
@thelleht it would have been useful if you were working on a 6502 built in a calculator that went 6502 -> bcd decoder -> 7seg or the such. For a normal desktop computer I can’t see it ever being useful either, I agree.
@ianhan79 There were BCD instructions in the 68000 too. Can honestly say I literally NEVER used them. I read they even took them out of later versions of the 680×0 series.
BCD was useful for 7seg displays driven by BCD decoders.