Letters from Professor Schawlow

Jan. 3, 1977

The date on this letter is incorrect. It was actually written in 1978, not 1977.


Stanford University
DEPARTMENT OF PHYSICS

Jan. 3, 1977
Mr. J. Torzewski
51625 Chestnut Road
Granger, IN 46530

Dear Mr. Torzewski:

I am glad to see, from the December issue of Interface Age, that you
are collecting Apple I programs. After more than a year of struggling with
the Apple I, I have pretty much put it aside since I have been able to get
the use of computers with better hardware and software support (Cromemco Z1
and now an Apple II). But I did write some programs for it, which are
enclosed with this letter.

The enclosed cassette has two tracks of programs: A, starting at 0
on my tape counter, and B which starts at 10. A contains
A1 (280-7FF) Program to display large characters
A2 (800-FFF) Extended monitor (apparently a design study for the
Apple II)
B contains
B1 (700-71C) Porgram to display ASCII HEX equivalents o f any
keyboard character
B2 (750-776) Program to display ASCII HEX equivalents of all
printing characters
B3 (7C0-7FF) Improved search subroutine for disassembler (like the
one I published in the October issue of Interface Age, except that it prints
only two lines of disassembled code)
B4 (700-9FF) Disassembler (as published in Dr. Dobb's Journal and
Interface Age)
B5 (A00-BFF) Primitive, line oriented text editor

I had expanded the Apple I memory to 20K and have a 16K Star Trek
and a floating point calculator program. However, I have taken out the 16K
chips and put them in the Apple II and so can no longer run these. If you
want, I can make copie on the Apple II, but I cannot test them.

It will be interesting to hear what programs you find. I would also
be interested in any information on how to interface the Apple I. I do have
an SWTP printer connected to it, but that is all.

Yous sincerely,

Arthur L. Schawlow
Professor

Jan. 23, 1977

Standford University
DEPARTMENT OF PHYSICS

Jan. 23, 1977
Mr. J. Torzewski
51625 Chestnut Road
Granger, IN 46530

Dear Mr. Torzewski:

I can give only partial answers to your questions, and it has taken me
some time to assemble this much information. We did not make the conversion to
16K memory chips. That was done by Steve Jobs of Apple Computer, and he did not
give us any documentation. Therefore, I have taken photos of the board to show
the connections, and these are enclosed.

In the breadboard area, there are five sockets. One of them (slides 13
and 15: at the left if breadboard area is at the top) is a socket for the flat
cable connecting to the SWTP printer. The next small socket and the large one
were for a project that was never completed, and so have no function. The two
on the right, labelled 74153 and 74139, are for integrated circuits with those
part numbers and are used in the 16K chips conversion. The connections to these
sockets are the light green wires shown in slides 17 and 19. Note that two
traces on the underside of the board have been cut for the 16K conversion. They
have been bridged by the red wires shown in the photograph. Also, the X-0
solder bridge in the chip select area must be cut. (The red wires in that area
were for another unfinished project and serve no useful function). Pin 14 of
integrated circuit 74S257 at location B-8 was bent so that it did not go into
the socket. If you have questions about the photograph and can't see where a
particular wire goes, we can look again at our board, but this is about all we
know.

Steve Jobs published an article describing how to interface to an STWP
printer, in the October 1976 issue of Interface Age. A copy of that article is
enclosed. We followed it, and the corresponding connections are the yellowish
green and red-white wires shown in slide 17. There is a switch to permit the
computer to output characters to the TV display when the printer is not in use.
It is indicated in Jobs' article and is mounted on the comptuer hoiusing so that
it is not visible in these photos.

I am enclosing a handwritten sheet listing some of the commands of the
extended monitor, a copy of the commands of the Apple II monitor, and a
disassembler listing of the extended monitor. Frankly, I believe that the
extended monitor was juast a design study for the Apple II, and it is not much use
for the Apple I especially if you have only 8K memory.

I hope to hear something of what you have been learning before too long.
Would it be worthwhile for you to start a newsletter and sell subscriptions?

Yous sincerely,

Arthur L. Schawlow
Professor

Sep. 17, 1978

Stanford University. Stanford. California 94303

ARTHEUR L. SCHAWLOW
J.G. Jackson - C.J. Wood
Professor of Phyiscs
(415) 407-4358

September 14, 1978

Mr. J. Torzewski
51625 Chestnut Road
Granger, IN 46530

Dear Mr. Torzewski:

Since you want it, and since nobody else has the
information, we will work out instructions for expanding
the memory of the Apple I. To start, I have ordered
duplicates of the slides, and should get them in a week
or so. We will then set out to expand the memroy again
and will note what we do as we do it. If all goes well,
we will have something to send you in a couple of weeks.

Our Apple I belongs to the University and it is
impractical to sell it now. There would be a lot of red
tape, and I would have no say as to who they sell it to.
So it seems best to keep it and make some limited use
of it.

Yous sincerely,

Arthur L. Schawlow

ALS:jf

Oct. 30, 1978

ARTHEUR L. SCHAWLOW
J.G. Jackson - C.J. Wood
Professor of Phyiscs
(415) 407-4358

October 30, 1978

Mr. J. Torzewski
51625 Chestnut Road
Granger, IN 46530

Dear Mr. Torzewski:

I am enclosing the instructions for converting an Apple I
to 20K memory. I am still not convinced that it is worth the
trouble, but it does work. We reconverted ours to check the
instructions.

I really don't know whether the speed of the memory chips
is critical. I don't know anything about the chips we have
used, and they may have been fast ones made surplus for some
other reason, but we did not pay a premium for speed. Still,
bad chips can be very troublesome, and so you should try to
get good ones if you can.

Do you have any information about input and output port
circuits for the Apple I? Even with the primitive BASIC, it
could make a useful controller if it could be interfaced with
transducers or relays.

I will be interested to hear how you make out if you do
try the memory conversion.

Yous sincerely,

Arthur L. Schawlow

Jul. 19, 1980

ARTHEUR L. SCHAWLOW
J.G. Jackson - C.J. Wood
Professor of Phyiscs
(415) 407-4358

July 10, 1980

Mr. J. Torzewski
51625 Chestnut Road
Granger, IN 46530

Dear Mr. Torzewski:

After I received your letter of January 26, 1979, I made a
number of attempts to copy the Apple I version of Star Trek for you,
but did not succeed. The recorder may have been defective, or it may
have been the tape.

Subsequently, some months ago, I ran across the enclosed tape in
the clearance sale pile at a local computer store. It is a copy of
Star Trek for the Apple I. But before I could get around to trying
it out, the students using our Apple I burned out something vital in
it, and so that computer no longer works. Apple won't repair it, and
I haven't found anyone else to do it yet. So, this tape is untested
and may be damaged, blank or otherwise useless. Whatever it is, you
can keep it. If you are still using the Apple I, you can try the
tape or throw it away as you wish.

Yous sincerely,

Arthur L. Schawlow

ALS:fj
Enclosure
(Dictated by Professor Schawlow;
signed in his absence by - fj.)