vanam@pttesac.UUCP (Marnix van Ammers) (10/29/86)
I've had one of the CardCo (now called C Ltd) 1 Megabyte memory
boards for about 3 months now. It's called the aMEGA RAM board.
There was some talk in this newsgroup about that board having
a problem. It apparently would cause wait states. I tested it
with Perry's memtest program and found that the FAST external
memory (the aMEGA board) was running 27% slower than my CHIP
internal memory.
Last week I read an article in Amazing Computing which showed me
how to fix my board. The article said that only the older boards
have this problem. I had to cut a trace and solder a tiny wire
between two points. I hadn't done any soldering in years and felt
somewhat nervous about doing this operation. But I went ahead and
did it anyway. I felt fortunate that the board worked (and still
is) after my soldering job. The article was on page 29 of
Amazing Computing Vol 1, Number 7.
After the fix I ran Perry's memtest program again. To my surprise,
not only did my FAST external memory speed up, but so did my CHIP
memory! My CHIP memory sped up by 15%, the FAST memory by 27%.
I hadn't done the memtest program with my aMEGA board disconnected
before, but apparently it had caused a slow down in my internal
memory (besides taking wait states on it's own). I'm hoping someone
out there will explain why.
Here are the results of Perry's memtest program:
Before modifying aMEGA card:
CHIP FAST DIFF
35400321 45000428 9600107
35416986 45117109 9700123
35383655 44900431 9516776
35400321 44833767 9433446
After modifying aMEGA card:
CHIP FAST DIFF
29950288 32433664 2483376
30200281 32416999 2216718
30066951 32533662 2466711
All tests were run with nothing else running.
As you can see I ran 4 tests before and only 3 afterwards. There
is still a difference of 8% between CHIP and RAM. This difference
was explained in an earlier posting. As I recall, that posting said
that under normal circumstances the difference would be around
4%. I suppose that the poster meant that normal circumstances are
when memory is not continuously accessed.
I would like to add an external zorro box (see I now know what zorro
means!) one day. I understand that C ltd is coming out with an
expansion box. I just hope that I won't have to throw my aMEGA board
away in order to use their expansion. $495 is a lot to throw away!
Marnix <- no, that's not an operating system! It's my name.
--
Marnix A. van\ Ammers
Home: (707) 644-9781 Work: (415) 545-8334
{ihnp4|ptsfa}!pttesac!vanam CIS: 70027,70hamilton@uiucuxc.CSO.UIUC.EDU (10/30/86)
vanam@pttesac says: > I've had one of the CardCo (now called C Ltd) 1 Megabyte memory > boards for about 3 months now. It's called the aMEGA RAM board. > > There was some talk in this newsgroup about that board having > a problem. It apparently would cause wait states. I tested it > with Perry's memtest program and found that the FAST external > memory (the aMEGA board) was running 27% slower than my CHIP > internal memory. > > ... > > After the fix I ran Perry's memtest program again. To my surprise, > not only did my FAST external memory speed up, but so did my CHIP > memory! My CHIP memory sped up by 15%, the FAST memory by 27%. > I hadn't done the memtest program with my aMEGA board disconnected > before, but apparently it had caused a slow down in my internal > memory (besides taking wait states on it's own). I'm hoping someone > out there will explain why. when you first ran perry's memtest, with the aMEGA connected, the program's code loaded into FAST mem, didn't it? so even while it was flogging data bytes in CHIP mem, the opcodes to do so were fetched from aMEGA ram. speedup aMEGA and those instructions fetch faster. wayne