smyoung@ames.arpa (Sarah M. Young) (03/30/88)
My group is having an emulation problem maybe someone else
has seen. We're trying to emulate a 68000 chip with an HP64000
68000 emulation pod and system. The chip is on a Force CPU-5
board. Whenever we try to access off-board memory (this is
VME bus, by the way), sooner or later (usually within a minute
or two) we get bus errors. Amazingly enough, some tests have
indicated the problem to be data-dependent, with writing 'FF's
working quite well while writing '00's failing almost immediately.
We have not had this problem with: any other Force or Plessey
board, llike CPU 2B or CPU 3; another emulator used with the
Force CPU 5 board (a MICE emulator). Force says they've never
seen this problem with any other emulators, and HP says they've
never seen this problem with any other boards. They both agree
that it should work, and that we don't seem to be doing anything
wrong that would keep it from working (and that it doesn't work).
Predictably, this isn't the biggest problem either company has
ever had, so can someone out there provide any clues? (We've
heard rumors of one or two other groups having this problem;
can anyone confirm or deny? We'd love names.)
Of course, I'm using 'we' advisedly, because I'm not speaking
for -- well, You know.
John Graybeal <smyoung@ames.arc.nasa.gov>bruce@voysys.UUCP (Bruce Beare) (03/31/88)
In article <6655@ames.arpa>, smyoung@ames.arpa (Sarah M. Young) writes: > My group is having an emulation problem maybe someone else > has seen. We're trying to emulate a 68000 chip with an HP64000 > 68000 emulation pod and system. The chip is on a Force CPU-5 > ... We have been having similar problems with their 6809E emulators. Whenever we use DMA (or if we have trap on illegal opcode enabled), the emulator will eventually get confused. This problem can be minimized by turning off the 'trap on illegal opcode' - then even if the emulator gets confused, the pod will continue to run the code. Bruce Beare Voysys Corporation ..!pyramid!ctnews!voysys!bruce Usual Disclaimer: I speak for me only, etc...