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View Full Version : Intel 8088-6 ES CPU in 5150 PC, anyone seen this before?



hharte
April 30th, 2003, 08:01 PM
Hi,

I have one fairly early serial number IBM 5150 PC in my collection, and it's in really nice shape. It came from a professor, and had stickers on most of the components in the machine with his name, phone number, and address. I guess back in '82 or so, these machines were fairly expensive and he didn't want it to grow legs. By those stickers, and since all of the components in the machine are genuine IBM, I'm pretty sure that the machine is all original.

The most interesting thing about it is that the CPU is marked I P8088-6 ES which I assume is an Intel 8088-6MHz, Engineering Sample. It also has a strange copper finned foil on the top of the package that looks hand-formed. What I'm unclear on is the 6MHz marking. As far as I know, Intel never produced a 6MHz part. All the other 8088's that I've seen are 8088-5 or 8088-8's, and I haven't seen any datasheets that mention the 6MHz part.

I'm curious if anyone has seen one of these before, or if they have heard of it. A close-up picture is on my web site at:

http://www.imsai8080.com/computers/IBM-XT/index.html

Thanks,
Howard

mbbrutman
May 3rd, 2003, 06:55 AM
I will check my PC5150 at work to see what the CPU is.

I know that my PC5150 is very old as well - it is a 64K motherboard with the limited BIOS that doesn't scan the ROM areas for ROM extensions on cards.

While I've never seen an 8088-6 before, it's possible that this machine may have been overclocked. Can you check the clock crystal to see if it is original? Going from 4.77 to 6Mhz would not have been a giant leap, and it still might be setup that way.

Erik
May 3rd, 2003, 09:09 AM
I'll have to pull out my old machine and check the markings on my processor.

One thing to consider is that the part number extension (-8, etc.) may not represent the clock speed directly. On the 8080s, at least, I know that they had markings that were effectively version numbers that could be translated back to maximum speed (i.e. the 8080-8 was a 2 MHz part, I think)

That may have changed by the time Intel started making the 8086/8088 line.

Erik

CP/M User
May 4th, 2003, 02:23 AM
"Erik" Wrote In message:

Hi Erik,

> I'll have to pull out my old machine and check the markings
> on my processor.

> One thing to consider is that the part number extension (-8, etc.)
> may not represent the clock speed directly. On the 8080s, at
> least, I know that they had markings that were effectively
> version numbers that could be translated back to maximum
> speed (i.e. the 8080-8 was a 2 MHz part, I think)

> That may have changed by the time Intel started making the
> 8086/8088 line.

I've heard of people removing resisters on their 486 mainboard
to slightly speed up the processing, but I don't think it's along the
same lines as what you're saying. But certainally the result is much
the same.

It's also risky doing this as it can fry the CPU! :-( But I'm not
game taking a solderning iron & removing resisters from a
mainboard.

Regards.

Jon Jarmon
June 6th, 2003, 08:43 PM
I've been looking for I.B.M. P.C. model 5150's in the thrift stores but have
NEVER found the really old revision A board ones.I do have 4 IBMPC's that are revision board B and all of them are maxed out at 640K of memory.They all have 2- 360k drives installed in each of them.
At least they all work.I also have 4 I.B.M. X.T's too.

Erik
June 7th, 2003, 06:11 AM
I managed to get an A and a B revision PC about two years ago. One is CGA, one is Monochrome and both work great.

The Rev A board is pretty much exactly like the first computer I ever owned. I have all of the original manuals and even the reciept for it. That's where I got DOS 1.0.

Erik

CP/M User
June 7th, 2003, 03:40 PM
"Erik" wrote in message:

> I managed to get an A and a B revision PC
> about two years ago. One is CGA, one is
> Monochrome and both work great.

> The Rev A board is pretty much exactly like
> the first computer I ever owned. I have all
> of the original manuals and even the reciept
> for it. That's where I got DOS 1.0.

I was lucky enough to see one of the original
IBM Personal Computers, unfortunately I
don't know if it was the Model A or B. This had
a mono screen, the 5.25" floppy disk as
standard & a external 3.5" floppy disk drive
& when turned on booted up BASIC in ROM.

The bootup disks I had didn't work on it, so
I'm guessing that the 5.25" disk drive was
broken (which I thought it might have been)
or it used a 160k floppy drive. But has
anyone ever seen the 3.5" external floppy
disk drive on it?

Cheers.

Jon Jarmon
June 7th, 2003, 04:16 PM
Hi Eric and CP/M user.Thats what I thought the first IBMPC's had a oddball 160k 5 & 1/4 inch drives on it.I've never seen a external 3 &1/2 inch microdisk drive for the PC.It Must be nice to have the first model of the PC
complete with all the original manuals,software,box and receipt.
I gave a IBMPC to my brother that had a 30mb SCSI hard drive in it with DOS 3.30 and Windows 1.01 just for laughs.

CP/M User
June 7th, 2003, 07:08 PM
"Jon Jarmon" wrote in message:

> Hi Eric and CP/M user.Thats what I
> thought the first IBMPC's had a oddball
> 160k 5 & 1/4 inch drives on it.I've never
> seen a external 3 &1/2 inch microdisk
> drive for the PC.It Must be nice to have
> the first model of the PC complete with
> all the original manuals,software,box
> and receipt.

It's horrible, because I cannot remember
what sort of connector the external 3.5"
floppy disk used. It had a simular sort of
connection to this card I've described in
'Long Shot #2' (but I cannot say for sure
that it had the same number of pins).
There was quite a few though.

We ended up throwning it out because
I couldn't get it to work (except for the
ROM BASIC which booted when it
didn't detect anything else). But I
couldn't get the Disk Drive to work or
if it was (it was such a long time now,
it wasn't reading my 5.25" disk to say
the least, so maybe it was a 160k
drive).

> I gave a IBMPC to my brother that had
> a 30mb SCSI hard drive in it with DOS
> 3.30 and Windows 1.01 just for laughs.

That sounds great. Oh oops! You should
have got GEM, that should have worked!

Cheers.

Jon Jarmon
June 7th, 2003, 07:17 PM
Hi CP/M user.I gave that particular machine to my brother because he worked at Microsoft.He understood the Windows 1.01(insider) joke.GEM would have been better as an actual useful WORKING interface.

CP/M User
June 8th, 2003, 01:45 AM
"Jon Jarmon" wrote in message:

> Hi CP/M user.I gave that particular machine
> to my brother because he worked at Microsoft.
> He understood the Windows 1.01(insider) joke.
> GEM would have been better as an actual useful
> WORKING interface.

Oops, unfortunately I forget very quickly! :-(
My latest activitys also tend to fill my head
with information (which is good in a way).

It's a pity you couldn't have done the
blind folded trick like they do in the Pepsi
ads! :-)

Cheers.