On Wed, 6 Aug 2025 at 12:47, Mike Schwab < [email protected]> wrote:
> LH loads 16 bits and extends the sign bit through the register. > ICM loads selected 8 bit bytes per the mask. > Is there a LLH Load Logical Halfword? > Yes. And LLGH which also zeros the high half of the 64-bit register, as you would expect. Which just adds to the question of Byte vs Character. One could argue, in line with the longstanding use of Halfword to mean 16 bits (and the default of "word" meaning 32) that they should have used "Quarterword" to mean 8 bits. But using Q in instruction names would have conflicted with Quadword, going in the other direction from the root "word". Tony H. On Wed, Aug 6, 2025 at 10:40 AM Charles Mills <[email protected]> wrote: > > > On Wed, 6 Aug 2025 05:42:55 -0400, David Cole <[email protected]> > wrote: > > > > >Why use B in one case and C in the other? > > > > I see what you are asking. Why 'B'? I don't know. Does any other opcode > > use B for Byte? Lots of C's: MVC, CLC, ICM, STC, ... > > > > I agree -- LC would have made more sense. Other than it might be > construed > > as or reserved for Load Complement; analogous to LCR. > > > > Charles > > > > ---------------------------------------------------------------------- > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
