aimania@killer.DALLAS.TX.US (Walter Rothe) (11/10/88)
I bought a CMI accelerator board at a good price from AMAZING, one of the two
amiga stores in Dallas and have run into some interesting information about
the board. I have a 2000 from the first trade in your 1000 deal and a
Starboard II with adapter card for conversion from 1000 to 2000. I also own
a Stardrive, also a Microbotics product. I have been real happy with the
service from Microbotics but it sure helps having them in town.
Anyway, I bought the CMI board with a 12MHZ 68881 and proceeded to try it out.
I took it home and found that it would not fit into the 68k socket well. It
interfered with the chip immediately to the right of the 68k. Being a
computer designer from way back, I had no qualms about buying a gold
extender socket and trying it out. This seemed to work. However, the Amiga
seemed to guru alot. I took the 68881 out and it worked fine.
I also tried the board without the Starboard and with the 68881 and it
worked fine. I called CMI and they said that they had run into some
crosstalk problems and were going to go to a multilayer board soon. They
said that they had a fix that seemed to correct the problem so I said I would
give it a try. They suggested cutting the etch to pin 6 of the 68k socket
and wiring a solid wire above the board to U3-12. Note that this does not
functionally change anything, it just may add some noise immunity or change
the reflection characteristics. They also suggested improving the grounding.
As a side note, the Lucas board has a 30 ohm resister in series with the
address strobe but I did not try this.
I also asked them what to set the jumper configuration to since the pamphlet
I got was missing the part about jumper settings. They suggested taking the
jumper off so that there were no jumpers on the board. The combination of
doing these two things helped alot. My system now made it through bootup
consistently and seemed to work fine most of the time. However, when I would
run my telecommunications package in the background trying to connect to
another machine over the phone and at the same time tried to load a large
program into Matt's DME editor, I could consistently Guru.
I called CMI back and they started accusing Microbotics and asked that
I call them and find out why it didn't work. I did this and Microbotics said
that they got a CMI board in and it did not work with any expansion devices.
At this point, I decided to give the board back to the dealer and let them
send it back. One of the dealers also sent all their CMI boards back also.
I really like the idea of having a cheap accelerator board but there seems
to be a few problems left to work out. Hope someone from CMI will address this.
By the way, the floating point speedup achieved from any 68881 connected to
a 68k will not be as great as that you can get by connecting a 68881
directly to a 68010 or 68020. There will still be a significant speedup on
double precision floating point calculations but only a small( 2 or 3 times )
speedup over the single precision Motorola FFP format.
--
Walter Rothe at the UNIX(Tm) Connection, Dallas, Tx
UUCP: {rutgers}!smu.killer.aimaniadave@dms3b1.UUCP (Dave Hanna) (11/11/88)
In article <6052@killer.DALLAS.TX.US> aimania@killer.DALLAS.TX.US (Walter Rothe) writes: [stuff about Accellerator board cross talk with expansion boards deleted] >By the way, the floating point speedup achieved from any 68881 connected to >a 68k will not be as great as that you can get by connecting a 68881 >directly to a 68010 or 68020. There will still be a significant speedup on ^^^^^ >double precision floating point calculations but only a small( 2 or 3 times ) >speedup over the single precision Motorola FFP format. Minor point, but connecting a 68881 to either a 68000 or a 68010 will not give you the speed up that it will on a 68020. Both the 68000 and 68010 interface to the device as an I/O peripheral, rather than through a co-processor interface, and there is a fairly significant amount of overhead in setting up the calculation, particularly for simple operations. Both the 68020 and 68030 use a co-processor interface, where 68881 operations are simply another instruction to the CPU. >Walter Rothe at the UNIX(Tm) Connection, Dallas, Tx -- Dave Hanna, Daltech MicroSystems | "Do or do not -- There is no try" P.O. Box 584, Bedford, TX 76095 | - Yoda (214) 358-4534 (817) 540-1524 | UUCP: ...!killer!gtmvax!dave |
billsey@agora.UUCP (Bill Seymour) (11/14/88)
From article <6052@killer.DALLAS.TX.US:, by aimania@killer.DALLAS.TX.US (Walter Rothe):
:
: Anyway, I bought the CMI board with a 12MHZ 68881 and proceeded to try it out.
: I took it home and found that it would not fit into the 68k socket well. It
: interfered with the chip immediately to the right of the 68k. Being a
: computer designer from way back, I had no qualms about buying a gold
: extender socket and trying it out. This seemed to work.
You were having clearance problems with the ROM chip? Was the ROM fully
seated in it's socket? OR by any chance did we leave some leads too long on the
back of our board? Clearance in the 2000 hasn't really been a problem...
: However, the Amiga
: seemed to guru alot. I took the 68881 out and it worked fine.
: I also tried the board without the Starboard and with the 68881 and it
: worked fine. I called CMI and they said that they had run into some
: crosstalk problems and were going to go to a multilayer board soon. They
: said that they had a fix that seemed to correct the problem so I said I would
: give it a try. They suggested cutting the etch to pin 6 of the 68k socket
: and wiring a solid wire above the board to U3-12. Note that this does not
: functionally change anything, it just may add some noise immunity or change
: the reflection characteristics.
Did you cut both ends of the trace? There is a second trace cut on the
top of the board on the trace going to pin 12 of U3. We found this particular
cross-talk problem with both the Starboard and the Micron board. Re-routing
the trace away from those other on the bottom of the board seems to be the
solution. We probably won't be going multilayer on the boards, since the new
layout does so well on this problem.
: They also suggested improving the grounding.
Who did you talk to that suggested grounding? That refers to the PAL
grounding mods for the 1000.... Sometimes the technical support people can get
confused as to which machine you're talking about... Being on the phone all
day can do that to you. :)
: As a side note, the Lucas board has a 30 ohm resister in series with the
: address strobe but I did not try this.
: I also asked them what to set the jumper configuration to since the pamphlet
: I got was missing the part about jumper settings. They suggested taking the
: jumper off so that there were no jumpers on the board. The combination of
: doing these two things helped alot. My system now made it through bootup
: consistently and seemed to work fine most of the time. However, when I would
: run my telecommunications package in the background trying to connect to
: another machine over the phone and at the same time tried to load a large
: program into Matt's DME editor, I could consistently Guru.
It sure sounds as if you have problems other than the normal ones...
The U8.PAL may be acting up (U8 is the PAL that generates the E clock, among
other things. When the E clock is acting up, you get symptoms associated with
serial port and floppy drive activity.) At this point our normal response
would be to ask you to either swap the board with another at your dealers, or
send it in to us for the swap. We don't have to replace very many boards, but
it's sometimes easier to replace than to troubleshoot over the phone.
: I called CMI back and they started accusing Microbotics and asked that
: I call them and find out why it didn't work. I did this and Microbotics said
: that they got a CMI board in and it did not work with any expansion devices.
Again, I'd like to find out who was talking to you at this point. Our
board does work with the Microbotics adapter board/Starboard combo. At least
the one I used in house did. Microbotics had a mod for their adapter board on
the very earliest ones, but that had something to do with auto-configure, I
thought...
If you could have your contact at Microbotics give me a call, I'd like
to talk to him about our board. Stating that our board 'doesn't work with any
expansion devices' is not only untrue, it's almost libellous... Our board is
working with pretty much all the expansion devices that let it phisically fit
into your machine. We can't test it with all expansion combinations, but with
as many Processor Accelerators out there as there are, we here about possible
incompatibilities pretty quickly! (BTW, the only two expansions I know of that
consistantly fail when our board is installed are the Techni-Soft RAMbo and
the PAL Jr., both on the 1000. And we're working on that...)
: At this point, I decided to give the board back to the dealer and let them
: send it back. One of the dealers also sent all their CMI boards back also.
Hmmm, I haven't seen any big volume returns.. Did they by any chance
only have a couple of boards in stock when they sent them all back? I'd have
noticed if we'd had any big returns...
: I really like the idea of having a cheap accelerator board but there seems
: to be a few problems left to work out. Hope someone from CMI will address this.
I hope I've cleared it up a little... It sure helps now that my local
site allows me to post...:
: By the way, the floating point speedup achieved from any 68881 connected to
: a 68k will not be as great as that you can get by connecting a 68881
: directly to a 68010 or 68020. There will still be a significant speedup on
: double precision floating point calculations but only a small( 2 or 3 times )
: speedup over the single precision Motorola FFP format.
Let's all hope for a single precision IEEE library for 1.4!
: --
: Walter Rothe at the UNIX(Tm) Connection, Dallas, Tx
: UUCP: {rutgers}!smu.killer.aimania
--
-Bill Seymour ...tektronix!reed!percival!agora!billsey
...tektronix!sequent!blowpig!billsey
Creative Microsystems Northwest Amiga Group At Home Sometimes
(503) 684-9300 (503) 656-7393 BBS (503) 640-0842