kirchner@uklirb.informatik.uni-kl.de (Reinhard Kirchner) (02/28/90)
From article <4975@scolex.sco.COM>, by seanf@sco.COM (Sean Fagan): > > Only one member of the 68k family implements the CALLM (and RETM) > instructions: the 68020. Nobody used it, apparantly, so it was dropped by > the time the '30 came out. > I remember on Electrica '88 a man from Motorola told me that CALLM and RTM where included because of a specific customer ( he didn't tell me which one ) and that this customer then did not use these instructions. So they where left out later on. R. Kirchner Univ. of Kaiserslautern, W-Germany kirchner@uklirb.informatik.uni-kl.de
ron@motmpl.UUCP (Ron Widell) (03/02/90)
In article <2609@uklirb.informatik.uni-kl.de> kirchner@uklirb.informatik.uni-kl.de (Reinhard Kirchner) writes: >From article <4975@scolex.sco.COM>, by seanf@sco.COM (Sean Fagan): >> >> Only one member of the 68k family implements the CALLM (and RETM) >> instructions: the 68020. Nobody used it, apparantly, so it was dropped by >> the time the '30 came out. >> >I remember on Electrica '88 a man from Motorola told me that CALLM and RTM >where included because of a specific customer ( he didn't tell me which one ) >and that this customer then did not use these instructions. So they where >left out later on. > From what I know of the situation (which is, admittedly, not everything) both of the above statements are true. The instructions were put in (the '020) to satisfy a request from a single (high-volume) customer who subsequently did not use them. Additionally, when the '030 was being designed, we polled all of the OEM customers we could track down (if you purchase from distribution we might not have found you) and discovered that *NO-ONE* was using these instructions in their code. They do require a tight linkage with and co- operation of the OS; thus it seemed highly unlikely that there would be applications out there at the locations we hadn't polled which used these instructions. In the final analysis, we couldn't justify the expense (both in silicon and clock cycles) of keeping them; and they could be simulated by the unimplemented instruction trap handler (maybe we should call the '030 a RISC :-)). This (their absence) was noted in the '030 user's manual, so I guess I'm a little suprised that they're only now being missed. Regards, -- Ron Widell, Field Applications Eng. |UUCP: {...}mcdchg!motmpl!ron Motorola Semiconductor Products, Inc., |Voice:(612)941-6800 9600 W. 76th St., Suite G | I'm from Silicon Tundra, Eden Prairie, Mn. 55344 -3718 | what could I know?
mslater@cup.portal.com (Michael Z Slater) (03/04/90)
>From article <4975@scolex.sco.COM>, by seanf@sco.COM (Sean Fagan): >> >> Only one member of the 68k family implements the CALLM (and RETM) >> instructions: the 68020. Nobody used it, apparantly, so it was dropped by >> the time the '30 came out. >> >I remember on Electrica '88 a man from Motorola told me that CALLM and RTM >where included because of a specific customer ( he didn't tell me which one ) >and that this customer then did not use these instructions. So they where >left out later on. I believe that this customer was Apollo. Michael Slater, Microprocessor Report mslater@cup.portal.com