From: lasner@watsun.cc.columbia.edu (Charles Lasner)
Subject: Re: What is so great about the PDP 10?
Reply-To: lasner@watsun.cc.columbia.edu (Charles Lasner)
Organization: Columbia University
Date: Mon, 21 Dec 1992 06:29:57 GMT

In article <9699354@zl2tnm.gen.nz> don@zl2tnm.gen.nz (Don Stokes) writes:
>lasner@watsun.cc.columbia.edu (Charles Lasner) writes:
>
>> As far as I'm concerned, System 3 never was a viable product, and its
>> followons 32, 34, 36, 38, 36-revisited, AS-400 are as miserable.  But that's
>> besides the point.  IBM isn't telling existing customers to chuck them by
>> manipulating them into a newer product by the extortive technique of telling
>> them they are officially obsoleting the product.  On the contrary, they kept
>> stringing along customers claiming that actual software was going to be
>> producted for these turkeys.
>
>Ummm, making it clear to all the /36 customers that their machine isn't
>going anywhere and they'll have to migrate to an AS/400 (or another vendor)
>to upgrade their hardware comes pretty close.  It looks to me like Jupiter
>all over again.

There was a period where IBM claimed a renewed "commitment" to the 36, thus
encouraging people to use the 36 while letting the 38 down.  Later, the
AS-400 was offered up as the next-generation panacea of system 3-land.  I
wouldn't compare it to what DEC did with 36-bit machines.  Moreover, 36 bit
machines have *real* software available for them.

>
>> >	Robin (VT180)	CP/M in a VT100, probably too expensive
>> 
>> Another stopgap; the VT-180 was a retrofit for existing VT-100 boxes; DEC
>> got caught up into that obligatory market where you just had to have a 
>> *something* that ran CP/M.  Having a minimal peripheral set made it a toy
>> even by CP/M standards.
>
>I don't know what DEC charged for it, but it doesn't seem a lot different
>to most of the CP/M boxes of the day.

True, but no possible upgrade was offered, no hard disk, etc.

>
>> >	Pro/350		F-11 chip, let down by s/w
>> 
>> No, let down by itself.  It's not compatible with certain key requirements of
>> existing -11 software.  It caused wasted efforts to attempt to make the
>> prevailing -11 software be compatible with its incompatibilities, and was
>> only partially successful and at great expense.  The incompatiblity could've
>> easily been avoided.  Same for DECmates.  Moral: don't let Harris Semiconductor
>> design the software configuration of your hardware you farm out the design
>> of to them.
>
>DEC should have put RSX on these boxes, not a crippled version.  The pdp11
>hackers who tried to use them got quickly frustrated by the nearly-RSX-but-
>not-quite-ness of P/OS.  RSX is good enough that you don't need to program
>on the bare metal to get anything done.  Serious pdp11 hackers ran RT11 on
>them.  Later came the Pro/325, which was only good for running RT11.
>
>I don't think DEC really knew what they were going to do with these boxes
>when they were designed.  At the time I got the impression DEC left the
>customer to figure out what to do with them.

*Real* RT-11 can't run on the PRO series.  RT-11 has been kludged to run
there, and absolute incompatibilities are noted in the documentation.  The
video space has been designed to exquisitely be in the wrong place.

>
>> >	DECmate III	Small box DECmate, shares many characteristics with 
>> >			DECmate II, but not parts (Intersil 6120)!
>> 
>> This was a partial VLSI treatment of the DM II to get the whole thing smaller.
>
>Not a bad size either.  That probably accounted a lot for the popularity 
>of the things; the system box sits neatly under the monitor with very little
>waste space.  I rather like them, even if Charles doesn't.  8-)

I didn't say I didn't like them, just that they are quite minimal.  They do
about what you'd expect from a machine whose entire disk complement is two
400K floppies.  Put a hard disk on it and it becomes more useful.

>
>> The III is the "toy" model and comes with only two floppies and no upgrade
>> possible, while the II has 2 floppies and optionally more floppies or a
>> hard disk.
>
>Gee Charles, so what did you do with the III -> III+ upgrade "kit" I sent 
>you?  

I made the III turn into a spare part on the shelf, and created a virtually
correct III+ in its place.  Since I have all the parts, it can be "quick-
changed" back into a III if need be, but instead is currently the much more
useful III+ which BTW can have two drives.

I would appreciate it if someone could send me a missing part:

I have the skid from an RX50 to hold in the drives in this box.  If you are
familiar with that plastic base part, it has 4 mounting holes in it.  This
is fine for the RX50, but in the III+, the front bezels of the drives are
double-thick - the RX33 is a TEAC drive with the normal TEAC front panel and
the one part that identifies the III+ - the plastic front bezel that proclaims
"PLUS" on it is an additional 1/4" thickness.  (Both III and III+ boxes merely
say "DECmate III" on them.)  So, the III+ uses an alternate skid to hold the
drives about 1/4" further toward the rear.  This part is easily identified
because it not only has the standard 4 holes as in the RX50-oriented skid, it
has 4 additional holes each 1/4" behind the corresponding RX50 hole.

So, if someone could send me an 8-holed skid, I would really appreciate it.  I
can also trade it for a 4-holed skid if required.  In someone's system that
uses an RX50 but has the 8-holed skid, the 4-holed skid is an adequate
replacement in that application, so I would appreciate the ability to swap.

Once I acquire the skid, I will have a truly authentic DM III+.  Don has even
graciously sent me the system serial label to paste on instead of the III's
label, so the transformation will be complete.

>
>(Admittedly, the "upgrade" does consist of chucking out everything that 
>makes it a III and replacing it with III+ parts.  You get to keep the
>box.  Maybe the power supply too, but it should really be replaced with 
>a bigger one.  8-)

Like I said, the III isn't upgradable, but the III box *is* :-).

>
>IIIs & III+s were very popular here.  I got mine off a pile of 40-odd of
>'em that were being disposed of (after DG did a better selling job into a 
>certain Govt Dept than DEC did) -- I got in early, people getting in afterward
>found the price had gone up a lot....  (It seems I managed to pick the only
>one in the pile with an APU (CP/M) board too....)
>
>--
>Don Stokes, ZL2TNM (DS555)                        don@zl2tnm.gen.nz (home)
>Network Manager, Computing Services Centre            don@vuw.ac.nz (work)
>Victoria University of Wellington, New Zealand              +64-4-495-5052

Someone else sent me an APU board, and I now have DECmate II CP/M-80 running
on the DM III+  While it was sold with only a single floppy, the interface
supports dual RX33 (TEAC FD-55GFR with a jumper added to a standard drive
setup for PC usage).  The DM II software depends on the existence of the
B: drive for its system generation and backup/restore operations.  All other
operations work on either a II or III+ equally from the CP/M-80 vantage point.
Of course from the PDP-8 side, it is easy to do a one-disk-oriented copy, and
this is provided from within Master Menu itself.  (The hard disk is used as
a buffer for the floppy before you switch diskettes, etc.)

Now the only thing I need is the III/III+ graphics board!

cjl


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