16 Jan
2012
16 Jan
'12
1:16 p.m.
I assume that it would be extremely difficult,
probably not worth the
effort, to modify the high order byte of the MFPT instruction at this
point for the 3rd party PDP-11 CPU boards, such as from Mentec.
Can anyone comment on this assumption? Might there be another
way for hardware to the tell a user which 3rd party board is being
used as a PDP-11?
Late versions of 11M+ use some fine details (timing?) to differentiate between a J11, and
the Mentec M1 and M100 (not J11 based).
Most of the 3rd party boards (including much of the Mentec stuff) are "just
J11's" maybe sped up/speed selected.
Tim.
16 Jan
16 Jan
1:58 p.m.
On Jan 16, 2012 10:28 AM, "Shoppa, Tim" <tshoppa at wmata.com> wrote:
Most of the 3rd party boards (including much of the Mentec stuff) are
"just
J11's" maybe sped up/speed selected.
Tim.
I wish the QED993 was just a fast J11. It's a Xilinx FPGA implementation
which has some compatibility issues.
I'd have to look at its configuration options. It might be possible to
alter the return values of the CPU type registers.
-Glen
8:06 p.m.
Glen Slick wrote:
On Jan 16, 2012 10:28 AM, "Shoppa, Tim"
<tshoppa at wmata.com> wrote:
Can you describe the fine details which make the QED993 different
Most of the 3rd party boards (including much of
the Mentec stuff) are
"just J11's" maybe sped up/speed selected.
Tim.
I wish the QED993 was just a fast J11. It's a Xilinx FPGA implementation
which has some compatibility issues.
from the J11 chip? For example, the early PDP-11
hardware did
not support the MFPT instruction. The PDP-11/73, PDP-11/83 and
PDP-11/84 which supported PMI memory could be tested for. The
Maintenance Register at 177750 had difference values for systems
which included the J11 chip.
Any specific differences for the QED993? Also, what is the official
spelling of QED993? If it is going to be noted, it is best to use the
official spelling used by QED.
I'd have to look at its configuration options. It
might be possible to
alter the return values of the CPU type registers.
That would not be needed if the compatibilities between the QED993
and the J11 from DEC can be tested for.
Jerome Fine
17 Jan
17 Jan
2:16 a.m.
On Mon, Jan 16, 2012 at 5:06 PM, Jerome H. Fine <jhfinedp3k at compsys.to> wrote:
Can you describe the fine details which make the QED993 different
from the J11 chip? ?For example, the early PDP-11 hardware did
not support the MFPT instruction. ?The PDP-11/73, PDP-11/83 and
PDP-11/84 which supported PMI memory could be tested for. ?The
Maintenance Register at 177750 had difference values for systems
which included the J11 chip.
Any specific differences for the QED993? ?Also, what is the official
spelling of QED993? ?If it is going to be noted, it is best to use the
official spelling used by QED.
QED is "Quickware Engineering & Design, Inc." In the documenation I
have it is "QED 993", with a space, not a dash.
I think one of the big differences is that the QED 993 had no support
for FP11 floating-point instructions at all. It wasn't like a DCJ11
chip without a companion FPJ11 Floating-Point Accelerator (FPA) chip.
It had no support for FP11 floating-point instructions at all. That
seemed to be one of the issues trying to get 2.11BSD to run on the QED
993. When I looked at the 2.11BSD code there seemed to be assumptions
in some places that FP11 instructions were always implemented.
-Glen
8:58 p.m.
Glen Slick wrote:
On Mon, Jan 16,
2012 at 5:06 PM, Jerome H. Fine <jhfinedp3k at compsys.to> wrote:
Can you describe the fine details which make the
QED993 different
from the J11 chip? For example, the early PDP-11 hardware did
not support the MFPT instruction. The PDP-11/73, PDP-11/83 and
PDP-11/84 which supported PMI memory could be tested for. The
Maintenance Register at 177750 had difference values for systems
which included the J11 chip.
Any specific differences for the QED993? Also, what is the official
spelling of QED993? If it is going to be noted, it is best to use the
official spelling used by QED.
QED is "Quickware Engineering & Design, Inc." In the documenation I
have it is "QED 993", with a space, not a dash.
I think one of the big differences is that the QED 993
had no support
for FP11 floating-point instructions at all. It wasn't like a DCJ11
chip without a companion FPJ11 Floating-Point Accelerator (FPA) chip.
It had no support for FP11 floating-point instructions at all. That
seemed to be one of the issues trying to get 2.11BSD to run on the QED
993. When I looked at the 2.11BSD code there seemed to be assumptions
in some places that FP11 instructions were always implemented.
As far as I know, every DEC J11 chip includes the floating point
instructions.
Most of the boards also allow the extra FPA chip, but that just speeds up
the execution of floating point calculations.
Having no floating point instruction support would be a way to distinguish
the QED 993 from a DEC J11 chip if every other implementation (including
DEC, Mentec, emulators, etc.) supports floating point instructions.
One thing about Ersatz-11 is that it would probably be able to configure
the CPU to match a QED 993 since it is so fine grained.
Jerome Fine
16 Jan
16 Jan
8:05 p.m.
Shoppa, Tim wrote:
I assume that
it would be extremely difficult, probably not worth the
effort, to modify the high order byte of the MFPT instruction at this
point for the 3rd party PDP-11 CPU boards, such as from Mentec.
Can anyone comment on this assumption? Might there be another
way for hardware to the tell a user which 3rd party board is being
used as a PDP-11?
Late versions of 11M+ use some fine details (timing?) to differentiate between a
J11, and the Mentec M1 and M100 (not J11 based).
Most of the 3rd party boards (including much of the
Mentec stuff) are "just J11's" maybe sped up/speed selected.
I seem to remember that the first Mentec board used the J11
from DEC. After that, Mentec developed their own
hardware.
I think that QED also went that route. I also remember a company
which was the very first hardware emulator which used a PC and
called the dick drives within the PDP-11 environment "container
files". Anyone remember their name? They developed a cross-
assembler that would run under DOS.
Jerome Fine
4603
days inactive
4605
days old
5 comments
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glen.slick＠gmail.com -
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tshoppa＠wmata.com