New Light on the Legend of Mel
Bill_vo...@transarc.com
group and others. (I've appended it for clarification - if you're not
familiar with the legend, you might want to read it first.)
In the legend, Mel worked for Royal McBee, an early computer company.
In the recent Boston Computer Museum Email Auction, I bought a set of
manuals and a Read Flip Flop (5" square PCB, 4 tubes, etc.) for an
Royal McBee LGP-30. The docs are dated 1959, and have some *great*
illustrations of how drums work (all 4096 words of storage, on this
particular system), what users will look like, etc...
One of our local systems wizards recently posted the legend on one of
our internal bboards to warm our hearts, which got me interested in
reading the LGP-30 manuals I'd acquired (I'm funny that way.) In the
manual for the LGP-30 ACT 1 (Algebraic Compiler and Translator)
Compiler, the preface contains the following attribution from Clay S.
Boswell, Jr. (apparently ACT 1's designer):
>> I wish to acknowledge my appreciation to the many people who
>> offered suggestions and criticisms of the ACT 1 System. In
>> particular... Mel Kaye of Royal McBee who did the bulk of the
>> programming.
Perhaps Mel Kaye is the one true Mel? Interesting data to ponder,
Regardless. I thought I should post this here, since the legend comes
up every so often and the docs for these systems can't be all that
common. This also provides a fine excuse to repost the legend itself.
Has anyone run across a Royal McBee system in the last few years? Now
there's a bit of cool ancient hardware I wouldn't mind for my computer
collection. At least I have the docs...
Bill von Hagen
w...@transarc.com
----------------------------------------------------------------------
A recent article devoted to the *macho* side of programming
made the bald and unvarnished statement:
Real Programmers write in Fortran.
Maybe they do now, in this decadent era of Lite beer, hand calculators and
"user-friendly" software but back in the Good Old Days, when the term
"software" sounded funny and Real Computers were made out of drums and vacuum
tubes, Real Programmers wrote in machine code. Not Fortran. Not RATFOR. Not,
even, assembly language. Machine Code.Raw, unadorned, inscrutable hexadecimal
numbers. Directly.
Lest a whole new generation of programmers grow up in ignorance of this
glorious past, I feel duty-bound to describe, as best I can through the
generation gap, how a Real Programmer wrote code. I'll call him Mel, because
that was his name.
I first met Mel when I went to work for Royal McBee Computer Corp., a
now-defunct subsidiary of the typewriter company. The firm manufactured the
LGP-30, a small, cheap (by the standards of the day) drum-memory computer, and
had just started to manufacture the RPC-4000, a much-improved, bigger, better,
faster -- drum-memory computer. Cores cost too much, and weren't here to stay,
anyway. (That's why you haven't heard of the company, or the computer.)
I had been hired to write a Fortran compiler for this new marvel and Mel was
my guide to its wonders. Mel didn't approve of compilers.
"If a program can't rewrite its own code," he asked, "what good is it?"
Mel had written, in hexadecimal, the most popular computer program the company
owned. It ran on the LGP-30 and played blackjack with potential customers at
computer shows. Its effect was always dramatic. The LGP-30 booth was packed at
every show, and the IBM salesmen stood around talking to each other. Whether
or not this actually sold computers was a question we never discussed.
Mel's job was to re-write the blackjack program for the RPC-4000. (Port? What
does that mean?) The new computer had a one-plus-one addressing scheme, in
which each machine instruction, in addition to the operation code and the
address of the needed operand, had a second address that indicated where, on
the revolving drum, the next instruction was located. In modern parlance,
every single instruction was followed by a GO TO! Put *that* in Pascal's pipe
and smoke it.
Mel loved the RPC-4000 because he could optimize his code: that is, locate
instructions on the drum so that just as one finished its job, the next would
be just arriving at the "read head" and available for immediate execution.
There was a program to do that job, an "optimizing assembler", but Mel refused
to use it.
"You never know where its going to put things", he explained, "so you'd have
to use separate constants".
It was a long time before I understood that remark. Since Mel knew the
numerical value of every operation code, and assigned his own drum addresses,
every instruction he wrote could also be considered a numerical constant. He
could pick up an earlier "add" instruction, say, and multiply by it, if it had
the right numeric value. His code was not easy for someone else to modify.
I compared Mel's hand-optimized programs with the same code massaged by the
optimizing assembler program, and Mel's always ran faster. That was because
the "top-down" method of program design hadn't been invented yet, and Mel
wouldn't have used it anyway. He wrote the innermost parts of his program
loops first, so they would get first choice of the optimum address locations
on the drum. The optimizing assembler wasn't smart enough to do it that way.
Mel never wrote time-delay loops, either, even when the balky Flexowriter
required a delay between output characters to work right. He just located
instructions on the drum so each successive one was just *past* the read head
when it was needed; the drum had to execute another complete revolution to
find the next instruction. He coined an unforgettable term for this procedure.
Although "optimum" is an absolute term, like "unique", it became common verbal
practice to make it relative: "not quite optimum" or "less optimum" or "not
very optimum". Mel called the maximum time-delay locations the "most
pessimum".
After he finished the blackjack program and got it to run, ("Even the
initializer is optimized", he said proudly) he got a Change Request from the
sales department. The program used an elegant (optimized) random number
generator to shuffle the "cards" and deal from the "deck", and some of the
salesmen felt it was too fair, since sometimes the customers lost. They wanted
Mel to modify the program so, at the setting of a sense switch on the console,
they could change the odds and let the customer win.
Mel balked. He felt this was patently dishonest, which it was, and that it
impinged on his personal integrity as a programmer, which it did, so he
refused to do it. The Head Salesman talked to Mel, as did the Big Boss and, at
the boss's urging, a few Fellow Programmers. Mel finally gave in and wrote the
code, but he got the test backwards, and, when the sense switch was turned on,
the program would cheat, winning every time. Mel was delighted with this,
claiming his subconscious was uncontrollably ethical, and adamantly refused to
fix it.
After Mel had left the company for greener pa$ture$, the Big Boss asked me to
look at the code and see if I could find the test and reverse it. Somewhat
reluctantly, I agreed to look. Tracking Mel's code was a real adventure.
I have often felt that programming is an art form, whose real value can only
be appreciated by another versed in the same arcane art; there are lovely gems
and brilliant coups hidden from human view and admiration, sometimes forever,
by the very nature of the process. You can learn a lot about an individual
just by reading through his code, even in hexadecimal. Mel was, I think, an
unsung genius.
Perhaps my greatest shock came when I found an innocent loop that had no test
in it. No test. *None*. Common sense said it had to be a closed loop, where
the program would circle, forever, endlessly. Program control passed right
through it, however, and safely out the other side. It took me two weeks to
figure it out.
The RPC-4000 computer had a really modern facility called an index register.
It allowed the programmer to write a program loop that used an indexed
instruction inside; each time through, the number in the index register was
added to the address of that instruction, so it would refer to the next datum
in a series. He had only to increment the index register each time through.
Mel never used it.
Instead, he would pull the instruction into a machine register, add one to its
address, and store it back. He would then execute the modified instruction
right from the register. The loop was written so this additional execution
time was taken into account -- just as this instruction finished, the next one
was right under the drum's read head, ready to go. But the loop had no test in
it.
The vital clue came when I noticed the index register bit, the bit that lay
between the address and the operation code in the instruction word, was turned
on-- yet Mel never used the index register, leaving it zero all the time. When
the light went on it nearly blinded me.
He had located the data he was working on near the top of memory -- the
largest locations the instructions could address -- so, after the last datum
was handled, incrementing the instruction address would make it overflow. The
carry would add one to the operation code, changing it to the next one in the
instruction set: a jump instruction. Sure enough, the next program instruction
was in address location zero, and the program went happily on its way.
I haven't kept in touch with Mel, so I don't know if he ever gave in to the
flood of change that has washed over programming techniques since those
long-gone days. I like to think he didn't. In any event, I was impressed
enough that I quit looking for the offending test, telling the Big Boss I
couldn't find it. He didn't seem surprised.
When I left the company, the blackjack program would still cheat if you turned
on the right sense switch, and I think that's how it should be. I didn't feel
comfortable hacking up the code of a Real Programmer."
-- Source: usenet: utastro!nather, May 21, 1983.
Chris P. Burton
couple of issues:
1 The Elliott 401, designed 1953, exhibited 1954, had the same drum
addressing scheme, operand-function-next instruction as mentioned
for the LGP30. We are restoring the only '401 in existence at the
Science Museum in London. One interesting task last year was
recovering the information from the drum, last switched-off in
1965. We have recovered most of the information, and are now
puzzling-out the meaning of the code, with this "non-sequential"
execution sequence. Hope to publish an article about it in
"Ressurection" in the next few months.
2 Surely they didn't use hexadecimal? I always thought hex came in
with 8-bit oriented objects, around the time of the introduction
of the IBM360 series. I would have preferred to have seen
references to octal, not hex. Assigning the letters A to F for the
super-decimal numbers seems a bit arcane for the 1950s.
--
Chris P. Burton, Wern Ddu, Llansilin, Oswestry, Shropshire, SY10 9BN, UK
ch...@envex.demon.co.uk Tel & fax: +44 (0) 691 70274
A member of the Computer Conservation Society.
Magnus Olsson
Chris P. Burton <ch...@envex.demon.co.uk> wrote:
>Fascinated to read the bit of folklore about Mel - it raises a
>couple of issues:
>1 The Elliott 401, designed 1953, exhibited 1954, had the same drum
> addressing scheme, operand-function-next instruction as mentioned
> for the LGP30.
I think this was common on drum-memory machines. And even if you
didn't have that kind of instructions, but a more "modern-looking"
instruction set with sequential execution, the drum revolution time
was still so long that it would be worthwhile to insert extra jump
instructions to the right address after each instruction.
>2 Surely they didn't use hexadecimal?
Why not?
> I always thought hex came in
> with 8-bit oriented objects, around the time of the introduction
> of the IBM360 series.
It is a common misapprehension that octal is in some sense more
"archaic" than hex (I've been a victim of it myself). Granted, modern
computers almost invariably use hex, but even some quite old ones did.
For example, SMIL, the first computer in Lund, which was built using
vacuum tubes and a drum memory in the mid-fifties, used hex, with A-F
for the last digits. SMIL had a 40-bit word length and 20-bit
instructions (packing 2 instructions into a word) and no concept of
8-bit bytes, but since 20 is a multiple of 4 and not 3 hex is mch more
suitable than octal (especially when itnerpreting one 40-bit word as
two instructions)
>I would have preferred to have seen
> references to octal, not hex.
Sorry, but your preferences are totally irrelevant. What if aI would've
preferred Mel to be called Eric? :-)
>Assigning the letters A to F for the
> super-decimal numbers seems a bit arcane for the 1950s.
Why? People where as logical then as they are now.
But some old computers did use totally different characters for the
digits above 9. In some cases the choices were related to the character
code chosen; in ASCII, that would mean using 0123456789:;<=>? rather
than 0-F.
Magnus Olsson | \e+ /_
yacc - the Computer Society at LU and LTH | \ Z / q
Lund, Sweden | >----<
mag...@thep.lu.se, m...@loglady.df.lth.se | / \===== g
PGP key available via finger or on request | /e- \q
Joel Sumner
an archive where it might be found? Thanks
-Joel Sumner
Motorola
jo...@oakhill.sps.mot.com
Carl Lowenstein
>It is a common misapprehension that octal is in some sense more
>"archaic" than hex (I've been a victim of it myself). Granted, modern
>computers almost invariably use hex, but even some quite old ones did.
I remember reading that Turing (yes that Turing) used base-32 arithmetic
to describe coding for some machine that used 5-level paper tape for I/O.
The Bendix G-15 (29 bits per word, as is now known to all spectators
at Usenix Jeopardy) used UVWXYZ for the hexadecimal digits above 9.
There's nothing quite so final as ZZZZZZZ, in my observation.
When the computer was annoyed with the operator, its generic error message
was Z0ZZ Y00.
carl
--
carl lowenstein marine physical lab u.c. san diego
{decvax|ucbvax} !ucsd!mpl!cdl c...@mpl.ucsd.edu
clowe...@ucsd.edu
Joseph Monzo
hexadecimal, but using F G J K Q W for 10 11 12 13 14 15.
Joseph Monzo
http://tonalsoft.com
Charles Richmond
II, but I did *not* know about the F G J K Q W on the LGP-30.
Interesting...
--
Charles Richmond
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
Quadibloc
> 2 Surely they didn't use hexadecimal?
However, this was before the IBM 360, and before C, so they chose their own way
to represent the digits beyond 9:
0123456789fgjkqw
John Savard
Quadibloc
> I have heard of using K S N J F L for 10 11 12 13 14 15 on the Illiac
> II, but I did *not* know about the F G J K Q W on the LGP-30.
10 11 12 13 14 15
C a b c d e f
Bendix G-15, SWAC u v w x y z
Monrobot XI S T U V W X
Datamatic D-1000 b c d e f g
Elbit 100 B C D E F G
LGP-30 f g j k q w
ILLIAC k s n j f l
Pacific Data Systems 1020 L C A S M D
John Savard
Christian Corti
> In fact according to its Programming Manual of 1957, the LGP-30 did use
> hexadecimal, but using F G J K Q W for 10 11 12 13 14 15.
Flexowriter code.
In fact, you can use other characters for 10..15 as long as the lower
four bits have the value 10..15, so instead of FGJKQW you can write
UTHCAS.
You can even replace 0..9 with ZBYRIDNMPE (or the other way round).
All this of coure only with 4-bit input ;-)
Christian
Dennis Boone
systems? I think the IAS machine (MISTIC, ILLIAC, etc) one is widely
reported.
De
Quadibloc
In addition to the usual one for the ILLIAC, "King Size Numbers Just for Laughs", a
search turned up an alternate: "Kind souls never josh fat ladies".
A similar search for the Pacific Data Systems sequence turned up no results.
But I *did* find some for the LGP-30.
FiberGlass Javelins Kill Quite Well
For God and Jesus Khrist(os), Quit Worrying
John Savard
Quadibloc
the PDS system, it does occur to me that its sequence of letters actually
lends itself to a mnemonic; something like
Lovely Computer Arithmetic; Some More Digits
John Savard
Phil Howell
Lgp30
http://obsolescenceguaranteed.blogspot.com/2016/06/using-simh-lgp-30-emulator.html?m=1
http://www.e-basteln.de/computing/lgp30/lgp30/