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What is an 8087 -6?

Peter Holowaty

New Member
Joined
May 28, 2003
Messages
7
Okay, so we already have a thread going on the 8088-6. I currently have a 8087 -6 installed in my PC/XT, and I have my doubt that the -6 is an indication of frequency. These things are all over all newgroup postings, but I can't seem to determine what makes them special. Is it a low power version?
 

CP/M User

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Joined
May 2, 2003
Messages
2,980
Location
Back of Burke (Guday!), Australia
Re: What is an 8087 -6?

"Peter Holowaty" wrote in message:

> Okay, so we already have a thread going on the 8088-6.
> I currently have a 8087 -6 installed in my PC/XT, and I
> have my doubt that the -6 is an indication of frequency.
> These things are all over all newgroup postings, but I
> can't seem to determine what makes them special. Is it
> a low power version?

Yes, I believe the 6 represents the Clock speed of it. 6Mhz
would be my answer. An 8087 also has a certain speed to
it because people used to say that if the speed of the
maths co-processor was slower than the CPU itself, it
would not give you the best performance. Where's if it was
faster, the co-processor would run at the speed the
computer does.

Cheers.
 

Erik

Site Administrator
Staff member
Joined
Apr 27, 2003
Messages
3,592
Location
San Jose, CA
I'm not sure that it's a direct representation of clock speed.

I know, for instance, that the C8080-8 is a 2 MHz part. I'm not sure how/why Intel designated it -8.

Erik
 

MattCarp

Experienced Member
Joined
Sep 5, 2003
Messages
269
Location
Atlanta, Georgia (USA)
suffix depends on the part

suffix depends on the part

For the 8087 the -6 suffix is the maximum clock speed. It'll work just fine in a PC/XT (4.77 MHz, of course).

For the 8080 I'm not sure what the meaning of the suffix is.

There's no standard convention, so the meaning of suffixes vary based on part.

Note that the 8087 (and 287, 387) runs at the same clock speed of the CPU, so you'll want to get a math coprocessor that operates at the same speed.
 

Jorg

Veteran Member
Joined
Aug 31, 2003
Messages
1,322
Location
Switzerland
Re: suffix depends on the part

Re: suffix depends on the part

MattCarp said:
Note that the 8087 (and 287, 387) runs at the same clock speed of the CPU, so you'll want to get a math coprocessor that operates at the same speed.

AFAIK the 286 in my IBM runs at 2/3 of the 286 clock speed
 

Barry

Member
Joined
Mar 13, 2004
Messages
22
8086 and 8087

8086 and 8087

The 6 and 7 have nothing to do with clock speed. The 8086 was the original Intel CPU with segmented memory so it could access more than 64k RAM.

The one IBM used in their PC was the 8088, which was basically a cheaper version of the same CPU that used an 8 bit data bus. The 8086 was a 16 bit CPU and the 8088 was sort of a 16 bit CPU and sort of an 8 bit CPU. It was slower but it was cheaper.

The 8087 isn't a CPU, it's an FPU, a Floating Point Unit that can be installed along with an 8086 or 8088 to speed up numeric processing. It was only useful with programs that were designed to use it such as some spreadsheets and most CAD programs. Since most PCs didn't have an FPU most software wasn't written to take advantage of them.

Most PCs came with a socket so you could add an 8087. But it was always an add-on.

The 486 was the first Intel CPU that included an FPU. The idea was that if the computer always had one programs would be written to take advantage of them. But manufacturers wanted to cut costs so Intel soon came out with the 486sx which left out the FPU.

The 386sx shouldn't be confused with the 486sx. The 386 never had an internal FPU. But it was a 32 bit processor and they made the sx version to cut costs, giving it a 16 bit data bus. Kind of like they did with the 8088.

Finally with the Pentium they included the FPU with every version of the processor and kept it that way.

Barry
 

Terry Yager

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Joined
May 1, 2003
Messages
8,763
Location
Saginaw, MI, USA 48601
Well, Intel's website was of no help. They seem to disavow any knowledge of anything before the 80186/88, which BTW, is still a current product:
Search Results for: All Products And '8087 processor'

No results matched your search.
Check the spelling, use similar words, or try a wildcard
at the end of your search string and search again.
--T
 

Terry Yager

Veteran Member
Joined
May 1, 2003
Messages
8,763
Location
Saginaw, MI, USA 48601
Re: 8086 and 8087

Re: 8086 and 8087

Barry said:
The one IBM used in their PC was the 8088, which was basically a cheaper version of the same CPU that used an 8 bit data bus. The 8086 was a 16 bit CPU and the 8088 was sort of a 16 bit CPU and sort of an 8 bit CPU. It was slower but it was cheaper.

Barry

Other chips of the day also had a similar (8/16-bit) archetechture, but Intel had enough savvy to promote thier 8/16-bitter as a "16-bit" chip, giving them a marketing advantage. A big contributing factor in the design of the 8088 was that it could take advantage of the base of 8-bit components which were already widely available, as well as considerably cheaper than 16-bit parts, so that the entire system could be built for less, not just the CPU. IIRC, IBM looked at other chips before deciding on the 8088, like the Motorolla 68000 and the Zylog Z8000, but decided on the 8088 only because Intel was able to meet thier needs by supplying enough chips fast enough to fit IBM's manufacturing schedule.

--T
 

CP/M User

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Joined
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Messages
2,980
Location
Back of Burke (Guday!), Australia
Re: 8086 and 8087

Re: 8086 and 8087

"Barry" wrote:

> The 6 and 7 have nothing to do with clock speed.
> The 8086 was the original Intel CPU with segmented
> memory so it could access more than 64k RAM.

> The one IBM used in their PC was the 8088, which
> was basically a cheaper version of the same CPU
> that used an 8 bit data bus. The 8086 was a 16 bit
> CPU and the 8088 was sort of a 16 bit CPU and sort
> of an 8 bit CPU. It was slower but it was cheaper.

That still doesn't explain what the 6 & 7 after the
CPU represent! But IIRC someone has already
explained this.

> The 8087 isn't a CPU...

Well I wasn't suggesting that the 8087 was a CPU.
However, it's true about what people have said about
the various speeds (I don't know if this applies for
the 8087 - I guess it would, but I know that the 80387
does).

> ...it's an FPU, a Floating Point Unit that can be
> installed along with an 8086 or 8088 to speed
> up numeric processing. It was only useful with
> programs that were designed to use it such as
> some spreadsheets and most CAD programs.
> Since most PCs didn't have an FPU most software
> wasn't written to take advantage of them.

> Most PCs came with a socket so you could add
> an 8087. But it was always an add-on.

I sure hope you're not explaining this to me! ;-)

> The 486 was the first Intel CPU that included an
> FPU. The idea was that if the computer always
> had one programs would be written to take
> advantage of them. But manufacturers wanted
> to cut costs so Intel soon came out with the
> 486sx which left out the FPU.

> The 386sx shouldn't be confused with the
> 486sx. The 386 never had an internal FPU.
> But it was a 32 bit processor and they made
> the sx version to cut costs, giving it a 16 bit
> data bus. Kind of like they did with the 8088.

I do do quite a bit of work with these types of
systems, so I know! ;-)

<Yawn!! Snip!> ;-)

Cheers,
CP/M User.
 

Barry

Member
Joined
Mar 13, 2004
Messages
22
> I sure hope you're not explaining this to me! ;-)
>
> I do do quite a bit of work with these types of
> systems, so I know! ;-)

I don't know anybody here and I don't know what anybody knows.

I'm just trying to answer a question.

This is fun stuff for me. If you already know about this, maybe somebody else doesn't.

I do know that when I talk with experienced programmers they hardly ever have the same experience that I had. I enjoy hearing the things they know and sharing what I know. If I already know something they share that's okay. Almost everybody knows something I don't know about and they'll get to it in time.

Barry
 

CP/M User

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Joined
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Messages
2,980
Location
Back of Burke (Guday!), Australia
"Barry" wrote:

>> I sure hope you're not explaining this to me! ;-)

>> I do do quite a bit of work with these types of
>> systems, so I know! ;-)

> I don't know anybody here and I don't know
> what anybody knows.

Sorry, it's just I get a little cockey sometimes, I
wasn't sure who the respondant was ment to be.

Reason I thought it was for me, was you just
happen to start by discussion what the numbers
after the CPU represent (which is what I'm still
not sure about!) & because this is such a old
thread brought back to life, I couldn't remember
if someone had suggested it (which I thought
they did), or it was just a thought.

> I'm just trying to answer a question.

> This is fun stuff for me. If you already know
> about this, maybe somebody else doesn't.

Well, that's another thing I was unsure. That's
perfectly fine if you're giving to the group as a
hole, which is why I'm guessing you didn't
have a respondants in question at the start.

> I do know that when I talk with experienced
> programmers they hardly ever have the
> same experience that I had. I enjoy hearing
> the things they know and sharing what I
> know. If I already know something they
> share that's okay. Almost everybody knows
> something I don't know about and they'll
> get to it in time.

Well, I try to agree with that, but as natural
since you're new here, I'm sorry if I came
over as hostile, sometimes I get cranky if
I see something which is in reference to
stuff I wrote with stuff I'd picked up
elsewhere. Trouble is, I pick up stuff from
all around & it get muddled sometimes. I
wasn't sure about the number after the
CPUs or FPUs.

Cheers,
CP/M User.
 

Barry

Member
Joined
Mar 13, 2004
Messages
22
> Well, I try to agree with that, but as natural
> since you're new here, I'm sorry if I came
> over as hostile

No problem. Hostile wasn't what I thought. I was afraid I'd stepped on some toes.

Barry
 

CP/M User

Veteran Member
Joined
May 2, 2003
Messages
2,980
Location
Back of Burke (Guday!), Australia
"Barry" wrote

>> Well, I try to agree with that, but as natural
>> since you're new here, I'm sorry if I came
>> over as hostile

> No problem. Hostile wasn't what I thought.
> I was afraid I'd stepped on some toes.

No toes were stepped on here, as far as I can
see!

Cheers,
CP/M User.
 
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