pardo@june.cs.washington.edu (David Keppel) (08/05/88)
>I respectfully differ. The 6809 has a SEX instruction ("Sign EXtend",
It also has Branch on LOw (BLO).
The TI 9900 is really kinky, it has the Branch and Load Workspace
Pointer (BLWP - Bullwhip) instruction.
All seriousness aside, if you ever get a chance to look at the
UMichigan list of opcodes (Circa 1970, since reprinted elsewhere) you
really should. Favorites include:
RETM # RETurn to Manufacturer
BROW # BRanch On Wednesday
HACF # Halt And Catch Fire
This last one (rumor has it) was actually implemented in a particular
IBM (if you ran the right program):
+ Temperature sensor is near the core memory.
+ Core memory must be written every time it is read.
+ Put a "branch to self" instruction in the right place.
+ One location keeps being read then written, gets hot.
+ Temperature sensor shuts down the computer.
Actually, I don't know if the opcode list was originally from UMich;
the earliest version that I've seen was from there. Anybody know of
older versions?
;-D on ( The processor blushes on instruction decode ) Pardo
pardo@cs.washington.edu
{rutgers,cornell,ucsd,ubc-cs,tektronix}!uw-beaver!june!pardo" Maynard) (08/09/88)
In article <5440@june.cs.washington.edu> pardo@uw-june.UUCP (David Keppel) writes: >Actually, I don't know if the opcode list was originally from UMich; >the earliest version that I've seen was from there. Anybody know of >older versions? This sounds like the legendary product announcement for the IBM 360/69. I've heard of that particular piece of writing, buit have never seen one. Anyone out there have (even a [legible] n-th generation Xerox copy) version of that they could send me? E-mail, please. -- Jay Maynard, EMT-P, K5ZC...>splut!< | Never ascribe to malice that which can uucp: uunet!nuchat! | adequately be explained by stupidity. hoptoad!academ!uhnix1!splut!jay +---------------------------------------- {killer,bellcore}!tness1! | Birthright Party '88: let's get spaced!
mbutts@mntgfx.mentor.com (Mike Butts) (08/09/88)
From article <5440@june.cs.washington.edu>, by pardo@june.cs.washington.edu (David Keppel): > All seriousness aside, if you ever get a chance to look at the > UMichigan list of opcodes (Circa 1970, since reprinted elsewhere) you > really should. Favorites include: > > RETM # RETurn to Manufacturer > BROW # BRanch On Wednesday > HACF # Halt And Catch Fire > > This last one (rumor has it) was actually implemented in a particular > IBM (if you ran the right program): > > + Temperature sensor is near the core memory. > + Core memory must be written every time it is read. > + Put a "branch to self" instruction in the right place. > + One location keeps being read then written, gets hot. > + Temperature sensor shuts down the computer. > Early versions of the Floating Point Systems FPS-164 minisuper had what amounted to a Halt and Commit Suicide instruction similar to the above. The main memory was built out of 16K DRAMs (circa 1980). The machine has a REFResh instruction, which forces a memory refresh cycle to occur, allowing diagnostic scope loops to appear stable, without unsynchronized refresh cycles floating around. Since the 164 has a 64-bit multi-field instruction word, the following instruction is valid: "REFR; JMP .". This will force the entire memory system to do refresh cycles every cycle. Since the memory normally draws power one bank at a time, the power demand of all memories cycling all the time greatly exceeds the capacity of the memory system +12V supply. It current-limits, and the power monitor shuts the computer down, filling the panel with red lights. Since the memory is volatile, the entire memory and CPU state are gone, leaving no trace of how the suicidal instruction occured. It wasn't as bad as it sounds, since REFR only worked in supervisor mode. The problem was solved by fitting a watchdog which would NOP a REFR if one had occured in the last 16 cycles. -- Mike Butts, Research Engineer KC7IT 503-626-1302 Mentor Graphics Corp., 8500 SW Creekside Place, Beaverton OR 97005 ...!{sequent,tessi,apollo}!mntgfx!mbutts OR mbutts@pdx.MENTOR.COM These are my opinions, & not necessarily those of Mentor Graphics.
peter@ficc.UUCP (Peter da Silva) (08/10/88)
Ah yes. If anyone out there has a Compucolor-2 (a Z-80 based PC from the early '80s) you can implement HACF from Basic: 10 FOR I = 1 TO 255: OUT 6,I: NEXT I don't know what port 6 did, but I suspect that it had something to do with the power supply. In any case the machine would start overheating and you had to pull the AC cord out to prevent it smoking. -- Peter da Silva, Ferranti International Controls Corporation, sugar!ficc!peter. "You made a TIME MACHINE out of a VOLKSWAGEN BEETLE?" "Well, I couldn't afford another deLorean." "But how do you ever get it up to 88 miles per hour????"
hwt@leibniz.UUCP (Henry Troup) (08/11/88)
Someone mentioned the HCF (Halt and Catch Fire) opcode - the IBM 3800 printer is a continuous form laser printer. Halt and catch fire is a reasonably regular occurence, or was - whenever there's a problem, paper stops in the hot fuser... The toner was also carcinogenic but they changed that...