dwatola@YODA.EECS.WSU.EDU (12/01/90)
hi again, just in case anyone is getting anxious, or if anyone is still interested, here is what's going on with my emulator. it is all but finished. only a few (rare) instructions need to be implemented and the sucker needs to be debugged (my flag emulation is apparently off). i only made a few compromises, the main one being that i ditched all BCD support. as far as i am concerned, it is a waste of time since i never use it. ditching the half-carry flag emulation sped up the program considerably (and yes, it is quite fast on this 25 MHz NeXT N1000). I also made some slight compromises in portability that should be easy to work around (especially if you are running 'real' BSD4.3). i am amazed that i had the time to do what i have done so far, so who knows when i will actually finish. in the next few weeks i have to design and lay out an entire vlsi chip plus prepare for finals. xmas break is looking good though--i'll get back to yall around the second week of january. dave watola dwatola@nextasy2.eecs.wsu.edu dwatola@yoda.eecs.wsu.edu "you're just a heroin face!" - R. Smith
del@fnx.UUCP (Dag Erik Lindberg) (12/09/90)
In article <9012010454.AA22006@yoda.eecs.wsu.edu> dwatola@YODA.EECS.WSU.EDU writes: > >apparently off). i only made a few compromises, the main one being that I am impressed with your effort, and look forward to seeing what you have done. >i ditched all BCD support. as far as i am concerned, it is a waste of time >since i never use it. ditching the half-carry flag emulation sped up the This is unfortunate, and will break more programs than you might suspect. The following seemingly innocuous code is a fairly common and extremely space efficient hack to convert a 4 bit binary number into ASCII ("0"-"F") representation of the hex value: add a,090H ; Set overflow character daa adc a,040H ; Add with ASCII offset daa Notice that it uses only 6 bytes, but includes the 'daa' (Decimal Adjust Accumulator), which is a BCD opcode. -- del AKA Erik Lindberg uunet!pilchuck!fnx!del Who is John Galt?