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'[OT] LET'
2014\05\12@071832 by IVP

face picon face
> When I started programming in the 80's, the let statement seemed
> pretty stupid... commodore code...  copy the value of the variable
> to a register, copy the value you want to set into another register,
> sys a kernel routine to copy the value to it, then sys another routine
One the most useful books I bought when programming the C64
was one that I still refer to from time to time. "What's Really Inside
The Commodore 64" by Milton Bathurst, 1983, is a commented
disassembly of the machine language of the operating system (I also
have a companion book, The Anatomy Of The 1541 Disk Drive,
also a commented disassembly).

A really cool thing about the C64 was that it had shadow RAM at
the same address as the ROMs, so you could make a copy of the
O/S in RAM and edit it. This included devising new instructions/
tokens for BASIC and writing your own ML routines to process
them, or alter BASIC or KERNEL functions. I had a lot of fun
with it, as well as valuable learning as to how ML works. They
packed a lot into 2 x 8k and to see it explained line by line was
just great

FYI, on the C64 LET is detected and processed as a token but
with the same routine that simply processes the variable following
as if there was no LET

$A7F1  BCC $A804 ;perform LET
....
$A804  JMP $A9A5 ;execute command LET
....
$A9A5  JSR $B08B ;gather name and get pointer to variable

etc

Ahhh, that takes me back

Joe
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2014\05\12@074244 by RussellMc

face picon face
On 12 May 2014 23:18, IVP <spam_OUTjoecolquittTakeThisOuTspamclear.net.nz> wrote:

> > When I started programming in the 80's, the let statement seemed
> > pretty stupid... commodore code...  copy the value of the variable
> > to a register, copy the value you want to set into another register,
> > sys a kernel routine to copy the value to it, then sys another routine
>
> A really cool thing about the C64 was that it had shadow RAM at
> the same address as the ROMs, so you could make a copy of the
> O/S in RAM and edit it.


I found something vaguely the opposite with Apple II.
I built a communication aid for a very severely handicapped user, which
linked two Apple II's - one running the user's program and another running
the communicator. An interface card in each provided a bridge between the
two systems.

As much as possible was in Apple BASIC but I wrote machine code programs
(sans assembler) for the 6502 to carry out some functions. I found that the
BASIC program was being corrupted by my machine code - AFAIR some constants
were being altered so that if you saved the program after running it did
different things than when first loaded.

This does not feel QUITE right - a bit more thinking (or somebody else's
comment) may refine:
.... Gets worse as I try to recall - I'll leave as I recall it and it may
clarify as it knocks around the back of my brain: So ...

The "problem" was that the system used program RAM memory as variable
memory and would alter program values. The solution was to carry out an
assignment that forced a new value to be used prior to calling the machine
code programs so that a memory area outside occupied program memory was
then used. [Yes. Doesn't quite make sense. Somebody else will have met
this].


              Russell
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2014\05\12@083413 by IVP

face picon face
> shadow RAM at the same address as the ROMs,

> I found something vaguely the opposite with Apple II.

Being at the same address as ROM, the 2 x 8k of RAM was
probably largely unused by most people, and certainly the O/S
didn't use it unless asked to. To access an 8k bank you had to
turn the corresponding BASIC or KERNEL ROM off and hand
over control to ML. Being out of reach of the O/S (BASIC
variable storage etc) it was a very useful place to store large
amounts of data like bitmapped screens / character sets, or ML
routines

The memory used for BASIC normally went from $0801 to
$9FFF. Programs built from $0801 upwards and variables
were stored from $9FFF downwards. Inevitably there would
be corruption and crashes as either the program got longer and
ran into the variables it created or you went a bit mad with
variable or string creation.

The BASIC ROM (and the underlying RAM) went from $A000
to $BFFF, but of course you couldn't turn BASIC off to access
the $A000 RAM for BASIC variables. However, by making an
editable soft copy of BASIC, it was (ISTR) possible to change
the default vectors and store variables at $CFFF -> $C000, which
was RAM not overlaid by ROM, the KERNEL ROM being at
$E000 to $FFFF, and other parts of the O/S at $D000 - $DFFF

Joe
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2014\05\12@111054 by Justin Richards

face picon face
>  I had a lot of fun
> with it, as well as valuable learning as to how ML works. They
> packed a lot into 2 x 8k and to see it explained line by line was
> just great.
>

Was a special dis-assembler cartridge required to do assembly.  I wanted to
learn assembly back then but the lack of cartridge seemed to be the
stumbling block.  I did enjoy programming the user interface to drive LEDs
solenoids etc.
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2014\05\12@135058 by John Guillory

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Yeah, when in machine language you could disable basic and use it as ram.  On the 80x86, there's another cool trick similiar to the commodore that you do something like:

Label1: Mov AX, 1
Db 3Dh
Label2: Mov ax, 2
Db 3dh
Label3: mov ax, 3
Cmp ax, 1
JZ read:
Cmp ax, 2
Jz write
Mov DX, verify


The 3d may be another byte, it's been a long time...

Where it allows 3 different  entry points to the same code... The first byte turns the mov into a Cmp...

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On May 12, 2014, at 6:18 AM, IVP <joecolquittspamKILLspamclear.net.nz> wrote:

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2014\05\12@135538 by John Guillory

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The commodore disk drives could be programmed as well.  In fact, it was simple to swap the load and save routines, but unless you told the computer they was swapped, a save wasn't setup to allocate room for the program...

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2014\05\12@165459 by IVP

face picon face
> Was a special dis-assembler cartridge required to do assembly.

I used a wonderful little program called Zoom. Very small, could
fit into any 4k block, and was completely relocatable. So if you
had a copy installed and working in the $C000-$CFFF RAM
and decided that you then wanted to use $C000 RAM for eg an
ML program instead, you simply used Zoom to copy itself from
$C000 to say $8000 and ran it there. And could be saved and
loaded from any memory location too of course. Great stuff. I
tried ohers like Hesmon but they were nothing like Zoom

> I did enjoy programming the user interface to drive LEDs
> solenoids etc.

Blew out more than a couple of 6522 VIA I/O ICs myself !! :-)

I suddenly feel like writing a program

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2014\05\12@172254 by IVP

face picon face
> On the 80x86, there's another cool trick
> Where it allows 3 different  entry points to the same code...
The 6510 has quite a few undocumented opcodes that the really
nerdy thought would bewilder casual users. For example there
were several that could be strung together in the middle of bona
fide-looking ML which looked like data (came up as ??? in a
disassembly) and looked nonsensical. But one function was to
actually operate as a computed branch and NOPs. So you
could appear to jump into the middle of a series of data bytes
without a crash, ending up in a common routine from one of
several entry points

Some opcodes were seemingly useless or innocuous, like one
that just did LDX $#0A, or LDY (X),Y. Some were NOPs,
like the official one, $#EA

Others were not so cool. There were no opcodes ending in 2
(02, 12, ... F2). If you happened to execute an x2 byte the
processor/machine would just freeze and only a h/w reset could
get you out of it

Joe
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2014\05\12@173322 by IVP

face picon face
> The commodore disk drives could be programmed as well

People did some very useful hacking for the 1541, most notably
greatly improving the transfer rate, because the I/O routines in the
C64 were written for the achingly, hair-pullingly slow Datasette.

Joe
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2014\05\12@213812 by John Guillory

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Hmmm I just had a cool semi random thought.  Grab an old commodore setup and program the disk drives to use  multiple drives and disk as a raid array. --
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On May 12, 2014, at 4:33 PM, IVP <KILLspamjoecolquittKILLspamspamclear.net.nz> wrote:

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2014\05\12@214451 by John Guillory

picon face
I've read about some of the undocumented op codes.  And yes, couldn't find a use for any of them!  ;-)
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On May 12, 2014, at 4:22 PM, IVP <spamBeGonejoecolquittspamBeGonespamclear.net.nz> wrote:

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2014\05\12@222038 by IVP

face picon face
> Grab an old commodore setup and program the disk drives to
> use  multiple drives and disk as a raid array

More than one drive, at least two anyway, could be used together
by shorting something out in the h/w to make it a ,9 device instead
of the default ,8. I installed a switch on the back of my 1541 to do
that, for copying diskettes from one drive to another

Oh, and wow, the day I was told you could clip the sleeve of the
diskette and be able to use the other side of it !!

Joe
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2014\05\12@222420 by Richard R. Pope

picon face
John,
    That could be done. I had a friend who was a hacker in the truest sense of the word. He had built the hardware interface and wrote a program that allowed him to access an IBM-360 hard drive from a C-64. I believe that it was all of 1 MB. I don't remember how many platters there were but I do know that it ran on 240 volts. It made quite a whine on power up. I still had my Vic-20, C-64. C-128 and I had just bought an Amiga 1000. I was thrilled. 256KB of graphics ram and I bought an expansion case with 1MB of fast ram. I then bought enough chips to bring the fast ram up to 3MB. I also bought an external floppy drive. I could leave the WorkBench disk in the internal drive and use the external drive for programs and data storage. After I boosted the fast ram to 3Meg I setup a ram disc and transferred the WorkBench to it from floppy disc on boot up. Now both floppy drives were available for programs and data. Also the speed of WorkBench was very fast. There was no hard drive interface available for the Amiga yet but that quickly changed. I then added a 30MB Seagate SCSI drive. I was in heaven at this point.
    I found a case made by Seagate that could house up to 8 MFF drives and an Adaptec interface card for SCSI to MFF. I was able to buy 8 250MB MFF drives. I now had 2 GB of storage space on my Amigas. They sounded a lot like that 1 MB drive that my friend used. The Adaptec card allowed you to program the boot sequence so that each drive was delayed for a short period of time on a cold start. This reduced the amount of current that was drawn as the disc drives spun up to speed.
    I had used the VIC and the Cs to learn how to program in BASIC and 6502 Assembly. I had four 1541s and an Epson printer hooked up to my Cs. I then learned how to make the Amiga talk to the Cs and I had a very primitive network setup. I added additional Amigas including an A4000T. The Amigas were connected with arcnet.
    I taught myself AmigaBASIC which was a modified version of MS-BASIC. It was easy to port C-BASIC programs over to AmigaBASIC. I then went on to learn 68xxx assembler. I dappled in Forth and FORTRAN. I then learned how to program in C. I then built a PC out of necessity. I learned MS-Dos and MS-Dos scripts. I never learned Intel assembler as Win95 was available and I wasn't writing any programs for the compatibles. It was games that eventually pulled me away from the Amigas and into the compatible camp. As gamers left the Amiga market because of Commodore shooting itself in the foot I slowly quit using my Amigas for longer and longer periods of time. I eventually sold all of my C= equipment. Ah yes those were the days. Today I write programs for Pics and C/MRI. Ah and these are the days. No better and no worse just different..
Thanks for the thoughts,
rich!

On 5/12/2014 8:37 PM, John Guillory wrote:
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2014\05\12@222744 by Richard R. Pope

picon face
Joe,
    The Cs supported up to 4 154xs and two printers. The C serial bus was a cut down parallel bus but I forgot what it was based on. Yes, you could cut a notch on the other side of the disc but this was risky as the other side had failed certification.
Thanks,
rich!

On 5/12/2014 9:20 PM, IVP wrote:
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2014\05\12@223740 by IVP

face picon face
> I had a friend who was a hacker in the truest sense of the word. He
> had built the hardware interface and wrote a program that allowed
> him to access an IBM-360 hard drive from a C-64

I read about such things in Compute ! and Compute ! Gazette but
never tried it myself. Was still exploring the insides of the C64 when
I was gifted an IBM luggable and then a Commodore PC20, which
had DOS and a 20MB HDD, so there was little point. Just carried
on using the C64 for electronics and ML

Joe
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2014\05\12@225201 by Lyle Hazelwood

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Richard,

> Amiga 1000. I was thrilled. 256KB of graphics ram and I bought an

Nice to know there are other Amiga enthusiasts here.

I am currently writing software for the latest generation, The Amiga X1000.
Dual core PPC processor, and reasonably "standard" memory, hard drives,
peripherals, and modern graphics cards.. but still works and feels like its
namesake. A fair share of the classic software will run unchanged on the
new system.

There is a 4-core board in development as well.
:)
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2014\05\12@225825 by Richard R. Pope

picon face
Lyle,
    Very interesting, Could you please send me a link about the latest Amigas? The hardware and software? I miss WorkBench. It is so much better than Windoze or Mac.
Thanks,
rich!

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2014\05\12@231736 by Richard R. Pope

picon face
Joe,
    Those magazines were very good. It was because the articles were written by people who loved their C= equipment as much as the people who read the magazine. I got a big kick out of stripping an Amiga down to just 128MB of ram and doing multitasking with it. Was it slow, yes, but it could be done. The look on the faces of people who had been only exposed to compatibles was great to see. And when I showed them what an Amiga with 2 meg of graphics, 8 megs of fast, and 32 megs of 32 bit ram running on a 040 at 50MHz was great.
     I can make my  dual Athlon system with XP run real slow at times. The Cs brought so many people in to computing.
Thanks,
rich!

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2014\05\13@023943 by William \Chops\ Westfield

face picon face
>  the let statement seemed pretty stupid.

Yes.  Yet I've heard various respectable CS types claim that NOT having a separate and explicit assignment operator/statement causes computer languages to be "confusing" to mathematicians, because of course in Mathematics, a statement like "a = a+1" can never be true.  Thus ":=" in Pascal, backward-arrow in APL, and etc.
Wikipedia has the details: http://en.wikipedia.org/wiki/Assignment_%28computer_science%29

BillW


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2014\05\13@171146 by IVP

face picon face
> The Cs brought so many people in to computing.

They sure did, also the dozens of other "home computer"
marques that were so popular (with boys !) in the 80s.

I'm rather disintereted in PCs.

Joe
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2014\05\13@191023 by Neil Cherry

flavicon
face
On 05/12/2014 04:54 PM, IVP wrote:
>> Was a special dis-assembler cartridge required to do assembly.
>
> I used a wonderful little program called Zoom. Very small, could
> fit into any 4k block, and was completely relocatable. So if you
> had a copy installed and working in the $C000-$CFFF RAM
> and decided that you then wanted to use $C000 RAM for eg an
> ML program instead, you simply used Zoom to copy itself from
> $C000 to say $8000 and ran it there. And could be saved and
> loaded from any memory location too of course. Great stuff. I
> tried ohers like Hesmon but they were nothing like Zoom
>
>> I did enjoy programming the user interface to drive LEDs
>> solenoids etc.
>
> Blew out more than a couple of 6522 VIA I/O ICs myself !! :-)
>
> I suddenly feel like writing a program

For the Atari (400 - 130XE) users there was Omnimon. I learned more
interrupting programs and figuring out what it was doing than I did
from most books. ;-)

PS: Sorry to drop in on the C64 party. ;-)

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2014\05\13@221517 by Richard R. Pope

picon face
Neil,
    No problem about you being an Atari fan. I wasn't one of these rabid C= guys that wasn't willing to appreciate other peoples points of view. Do you still have any Atari equipment?
Thanks,
rich!

On 5/13/2014 6:10 PM, Neil Cherry wrote:
> PS: Sorry to drop in on the C64 party. ;-)
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2014\05\13@222036 by Richard R. Pope

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Joe,
    I only switched over because of need and it is hard to maintain to completely different systems. By systems I mean a collection of computers, not just one computer. At one point I was running different different computers on three different networks. Now it is four computers on one network.
Thanks,
rich!
P.S. When C= quit production on the C-64 it had sold more C-64s than all other computers combined. You could compare the Vic to the Model T and the 64 to the Model A. Hugely successful.
rich!

On 5/13/2014 4:11 PM, IVP wrote:
>> The Cs brought so many people in to computing.
> They sure did, also the dozens of other "home computer"
> marques that were so popular (with boys !) in the 80s.
>
> I'm rather disintereted in PCs.
>
> Joe

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2014\05\13@232458 by Neil Cherry

flavicon
face
On 05/13/2014 10:15 PM, Richard R. Pope wrote:
> Neil,
>       No problem about you being an Atari fan. I wasn't one of these
> rabid C= guys that wasn't willing to appreciate other peoples points of
> view. Do you still have any Atari equipment?

Yup, I'm not giving up my Omnimon for anything! ;-)

For those that are not familiar with Omnimon, it's a ROM monitor with
all sorts of nifty entry points and assembly/disassembly tools. Together
with Don Lancaster's Apple II articles on how to reverse engineer taught
me tons about computing and electronics.

I'm hoping to get some spare time to play with a few peripherals but I'm
not going to say much further until I actually have something in process.
Too many ideas, not enough time.

I have donate some of my spare stuff to MARCH ( http://www.midatlanticretro..org/ ).
There are one or two things I won't give up but they have most of what I still
have anyway. :-)

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2014\05\13@235340 by John Gardner

picon face
Good fun. I happened to acquire a TI-74 programmable

calculator, circa 1985... A robust implementation of BASIC,

but otherwise a closed system. So I learned to hack...

:)

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2014\05\14@220217 by Richard R. Pope

picon face
John,
    That's cool! TI like RS made it very hard for independent developers. C= always made their systems wide open. This was one of the reasons that these computers were so popular.
Thanks,
rich!
On 5/13/2014 10:53 PM, John Gardner wrote:
> Good fun. I happened to acquire a TI-74 programmable
>
> calculator, circa 1985... A robust implementation of BASIC,
>
> but otherwise a closed system. So I learned to hack...
>
>   :)
>

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2014\05\14@222920 by John Gardner

picon face
At this remove it's hard to say what I'd've done with a more

user-friendly platform. My opinion is that TI shot themselves

in the foot with their user-unfriendly approach.

Not the first, or the last time...

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2014\05\14@232221 by RussellMc

face picon face
On 15 May 2014 14:29, John Gardner <RemoveMEgoflo3EraseMEspamEraseMEgmail.com> wrote:

> At this remove it's hard to say what I'd've done with a more
> user-friendly platform. My opinion is that TI shot themselves
> in the foot with their user-unfriendly approach.
> Not the first, or the last time...
>


And yet, TI still have their feet and are still standing, whereas MANY of
their erstwhile competitors are gone (and/or now part of TI).


           R
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2014\05\14@234626 by John Gardner

picon face
Yep. Whether because, or in spite of, is debatable.

Nat'l Semi data sheets were the best - Looked at one

lately?

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2014\05\15@025722 by William \Chops\ Westfield

face picon face

> And yet, TI still have their feet and are still standing

Is TI still in the personal computer business?  No.
They were just big enough overall to try PCs on a whim, fail, and continue onward with their 'core business.'

BillW



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2014\05\15@042123 by Peter Johansson

picon face
On Thu, May 15, 2014 at 2:57 AM, William "Chops" Westfield
<RemoveMEwestfwspam_OUTspamKILLspammac.com> wrote:

> Is TI still in the personal computer business?  No.

TI failed because they got in too late, charged too much, and most
importantly didn't release any of their machine specs and put a
stranglehold on external hardware and software development.

Of course, even if they had succeeded, they would have almost
certainly been killed by IBM (and the PC clones) along with everyone
else.
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2014\05\15@044209 by Richard R. Pope

picon face
Peter,
    Yep and the only reason IBM succeeded in dominating the small and medium businesses with computers is because they already had a strangle hold on the business computer market. At that time if a business wanted to computerize they pretty much had to go to IBM and you didn't buy a computer. You had to sign into a mutli-year lease where IBM had total control over hardware, software, and maintenance. The reason they could do this is because their reputation was extremely good. So they invented a small computer and then overwhelmed the market with it. With the scale of production they were able to sell their computer for less than what anyone else could.
    I will continue the story at a later time. I am not putting anyone or any company down. I am only telling the facts.
Thanks,
rich!

On 5/15/2014 3:21 AM, Peter Johansson wrote:
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2014\05\15@064519 by IVP

face picon face
> Yep and the only reason IBM succeeded in dominating the
> small and medium businesses with computers

Wasn't it also the case that "IBM-type" PCs proliferated,
compared with an at-that-time struggling Apple because Apple
chose not to license their system for general manufacture. I can't
honestly say what portion of the high(er) cost of a Mac was
down to quality or the lesser economy of scale

Joe
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2014\05\15@092412 by RussellMc

face picon face
On 15 May 2014 14:57, William "Chops" Westfield <EraseMEwestfwspamspamspamBeGonemac.com> wrote:

>
> >
> >
> And yet, TI still have their feet and are still standing
>
> >
> Is TI still in the personal computer business?  No.
>
>
Is IBM still in the personal computer business? ...
I (still) don't know what lessons should be learned from that.

(Almost as shocking as Minolta not being in the camera business!)

____________________

Something I've wondered for a while.

Given: Wang Labs -> DEC -> Compaq -> HP.

What comes next?


   R
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2014\05\15@100954 by Carl Denk

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On 5/15/2014 9:23 AM, RussellMc wrote:
> On 15 May 2014 14:57, William "Chops" Westfield <RemoveMEwestfwKILLspamspammac.com> wrote:
>
> Is IBM still in the personal computer business? ...
IBM sold personal computer to Lenovo (China) some time ago, maybe 15 years or more. The handwriting was on the wall, had to be mid 80'S, MY FIRST PC (had S100 buss (IEEE 696??) before that was bought from JDR Microdevices (Still in business), a AT clone by Mylex, forget who made the CGA video, but a close friend designe the QDP VIVA which was one of the first high resolution AT video cards made here in Cleveland, Ohio. Bought the stuff at Hamvention, a Dayton, Ohio ham/computer flee market, still goes today, if you can make that weekend.
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2014\05\15@104147 by John Gardner

picon face
....My opinion is that TI shot themselves in the foot...

I had in mind the TI-99/4a, which I think was the 1st widely

available (low-cost) 16-bit machine.

Being TI, though, they deliberately crippled the 99/4a to pre-

vent it competing with their minicomputer business. It did'nt -

They ended up giving them away.






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2014\05\15@104230 by Jean-Paul Louis

picon face
Yes Carl,
Hamvention in Dayton rocks.
I’ll be there too, most of friday, saturday and sunday for the great deals.

Jean-Paul
AC9GH

On May 15, 2014, at 10:09 AM, Carl Denk <cdenkSTOPspamspamspam_OUTwindstream.net> wrote:

> The


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2014\05\15@104900 by Isaac Marino Bavaresco

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Em 15/05/2014 11:09, Carl Denk escreveu:
> IBM sold personal computer to Lenovo (China) some time ago, maybe 15
> years or more. The handwriting was on the wall, had to be mid 80'S, MY
> FIRST PC (had S100 buss (IEEE 696??) before that was bought from JDR
> Microdevices (Still in business),
I used to buy from JDR about 20 years ago. It had a varied inventory of
electronic components and tools and was the only store we knew that sold
over the Internet and dispatched to Brazil (soon after that I met Mouser).

JDR now seems only a faint shadow of its past.

Isaac

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2014\05\15@112907 by John J. McDonough

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On Thu, 2014-05-15 at 10:42 -0400, Jean-Paul Louis wrote:
> Yes Carl,
> Hamvention in Dayton rocks.
> I’ll be there too, most of friday, saturday and sunday for the great deals.
>
> Jean-Paul
> AC9GH

Sadly, I won't be there.  Family obligations this year, and it has been
a number of years since something hasn't interfered.

Especially disappointing since there will be an NTS forum this year, and
as STM for Michigan I would like to be there,  many of the ECAC members
who I have worked with over the past year and haven't met will be there,
and I expect a significant announcement from Mike Corey.  So lots to
miss.

The best part is Thursday, tho, at Fairborn.  Lots of technical
presentations, and a bunch of incredibly smart and friendly folks.
http://www.qrparci.org/fdim

--McD


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2014\05\15@140005 by John Ferrell

face
flavicon
face
I could give you the other side of the story from the IBM employee's view.
We did not always have the best product but we were obligated to make it work and without losing money.
If the best products were the survivors DEC and Compaq would not have been swallowed by HP.
A Technology company that is a "One Trick Pony" does not have a future!

On 5/15/2014 4:42 AM, Richard R. Pope wrote:
>   I will continue the story at a later time. I am not putting anyone
> or any company down. I am only telling the facts.

-- John Ferrell W8CCW

"Go confidently in the direction of your dreams.
 Live the life you have imagined."
– Henry David Thoreau


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2014\05\15@190453 by RussellMc

face picon face
* I will continue the story at a later time. I am not putting anyone or any
company down. I am only telling the facts.*
Facts can be told of in a very wide range of ways.
The long arm of the Bob reacheth even into OT and if you post more on this
in the same tone I predict that you will wake him from his so far
slumbering and that verily he will stamp all over this so far interesting
thread. The comments are fine enough as a perspective but are put in such a
way that would indeed feel like :putting someone down" to some.
Perhaps even replacing the introduction with both the words AND the mindset
of "A significant factor in IBM doing so well for so long with computers
was ...".
This is NOT just a matter of semantics and pedantics - it is a genuine
shift of perspective to a more level viewing field - even if only to one
far edge of the level field.

FWIW, from my point of view, as a user and later manager of a small sized
business area without a vast amount of leverage into what was done - the
IBM PC was the computer of choice because it was the best value for money
or the best or the sensible only affordable or in any way achievable
computer at the time.

I was extremely surprised way back then to pay a visit to the boffins
backroom of a head office department in another city which I visited very
seldom, and to find a significant number of Apple IIs with people
programming using them intensively for major head office computing tasks.
That may have been just before the IBM PC entered its days of glory.

My occasional look through various IBM PC offerings of the day impressed me
with the strong focus on maintainability of the designs. Much of the
machines seemed to be accessible with few or no fasteners used - I recall
being impressed on the ability to swap out a hard drive from the front of
the computer without opening the casing. (I recall at one stage an HP
serviceman requiring all engineers to leave the room while he opened the
case on an HP 'Mini' (9830?) so that they could not see how it was done
:-). (Really).

____________

Some of that sounds very good to me. Wrap it right, with whatever else
seems pertinent wrapped similarly, and it may well go down well enough.

eg you said:

....
> and the only reason IBM succeeded
> ...
>
....
> The reason they could
> do this is because their reputation was extremely good.
> ...
>

.... With the scale
of production they were able to sell their computer for less than what
anyone else could.

I recall an aphorism from 'back then'.

          "Nobody ever got fired for buying IBM".

___________

FWIW, I may have been responsible for starting a process which caused
massive interim financial losses for IBM NZ (but a happy ending long term.)
I was not *responsible* and the consequences were not forseeable in any way
at all while I was involved (it took several years) but I started the
process quite independently of later consequences. [I managed to identify a
software system which seemed ideally suited to a major corporate task a day
before a high level team went on an overseas  fact-finding mission for the
same. Location and then use of the system and the fact that it ran on a
non-mainstream IBM line of hardware (I think seen as a very top end Mini)
meant that it almost certainly would not have been discovered by the team.
I put IBM and the team in touch with a just-before-leaving meeting, they
visited the US site and it went from there. Our company (then NZ's largest
corporate) ended up buying the system in a big way, and extending it very
extensively using the top then available compatible IBM hardware.
The T...... .. lawyers must have been better than the IBM lawyers or the
sales people and engineers too enthusiastic as the system performance fell
well below needed and guaranteed level and needed swapping out largish (by
NZ standards) quantities of 'boxes' for the new higher performance ones as
they became available. I think (memory may be wrong) that our need drove
the ongoing development of this line when it had not been intended. (Again.
memory may be wrong - longish ago and I was only an onlooker). I think the
story ended happily enough with IBM and T... partnering on the system
overall and selling it elsewhere in the world where it did OK. Again - that
may be dreaming :-).
But, once the action really got going, nobody knew that I had started it
:-). [[For the few (or less) who care or know the term "ICMS" will be an
adequate clue. And 'Sugraland' (yes, that one) has some US relevance. ]].



           Russell
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2014\05\18@164820 by Byron Jeff

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On Mon, May 12, 2014 at 11:39:40PM -0700, William "Chops" Westfield wrote:
> >  the let statement seemed pretty stupid.
>
> Yes.  Yet I've heard various respectable CS types claim that NOT having a
> separate and explicit assignment operator/statement causes computer
> languages to be "confusing" to mathematicians, because of course in
> Mathematics, a statement like "a = a+1" can never be true.  Thus ":=" in
> Pascal, backward-arrow in APL, and etc.

> Wikipedia has the details: http://en.wikipedia.org/wiki/Assignment_%28computer_science%29

That may or may not have been the initial impetus. A much simpler
explanation is that LET was a keyword that facilitated knowing what should
come next, therefore simplying the process of parsing the statement. As a
language designer, it's pretty easy for me to see that the statement:

A = 3

would require scanning through all possible keywords, reaching the end of
the list, then deciding it must be a variable and then it's an assignment
statement. Whereas:

LET A = 3

is keyworded with a specific keyword which is easy to find and defines the
semantics of the statement.

Parsing the latter is much easier.

BAJ

>
> BillW
>
>
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Clayton State University
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2014\05\26@185143 by IVP

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www.dailymail.co.uk/news/article-2639266/Its-hipster-Watch-confused-kids-try-make-sense-1970s-computer.html
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2014\05\27@145855 by Tamas Rudnai

face picon face
On 18 May 2014 13:54, Byron Jeff <spamBeGonebyronjeffSTOPspamspamEraseMEmail.clayton.edu> wrote:

> A = 3
>
> would require scanning through all possible keywords, reaching the end of
> the list, then deciding it must be a variable and then it's an assignment
> statement. Whereas:
>
> LET A = 3
>
> is keyworded with a specific keyword which is easy to find and defines the
> semantics of the statement.
>
> Parsing the latter is much easier.
>

Would that make any difference knowing that Basic implementations on old
(70s - 80s) computers were tokenizing Basic language before storing it in
memory or on tape/disk? Usually that happens when entering the source code
from the keyboard, therefore a slow lookup method should not be a big issue
-- and after tokenization this should not be matter as tokens are already
telling the interpreter what that is, right?

Tamas



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2014\05\27@190821 by Rupert Swarbrick

picon face
part 1 1576 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable)

Byron Jeff <KILLspambyronjeffspamBeGonespammail.clayton.edu> writes:
> That may or may not have been the initial impetus. A much simpler
> explanation is that LET was a keyword that facilitated knowing what should
> come next, therefore simplying the process of parsing the statement. As a
> language designer, it's pretty easy for me to see that the statement:
>
> A = 3
>
> would require scanning through all possible keywords, reaching the end of
> the list, then deciding it must be a variable and then it's an assignment
> statement. Whereas:
>
> LET A = 3
>
> is keyworded with a specific keyword which is easy to find and defines the
> semantics of the statement.
>
> Parsing the latter is much easier.

This is a nice insight, thanks. I wanted to add that it applies to
humans too! We're terrible at reasoning about mutable objects. I spent
an hour today debugging a mistake in a python script (SCons, in fact),
where someone had very carefully copied an "environment" object so that
they could override its properties. Unfortunately, they stored the
result like this:

  env = something
  orig_env = env
     for x in some_list:
     if is_funky (x):
        env = Clone(orig_env)
        env.some_flag = "way-cool"
        do_it (env)

(If confused: suppose that there are two elements in the list and the
first is funky, but not the second)

Forcing the original programmer to explicitly declare a local variable
would have avoided the problem.


Rupert


part 2 197 bytes content-type:text/plain; name="ATT00001.txt"
(decoded base64)

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2014\05\27@192953 by James Cameron

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On Tue, May 27, 2014 at 11:58:54AM -0700, Tamas Rudnai wrote:
{Quote hidden}

You're both right, in a way.

An example [1].

The Basic on the TRS-80 Model I Level II will tokenise the LET, and
the equals sign, but won't tokenise the variable name or the constant.

So after tokenising:

   LET A = 3

the buffer contains:

   0x8c (TOKEN LET)
   0x41 (ASCII A)
   0xd5 (TOKEN =)
   0x33 (ASCII 3)
   0x80 (TOKEN END)

The interpreter recognises variable names as different from tokens, as
tokens have a high bit set.  So when a variable name is encountered
without a LET token, the execution vector for the LET token is used.

Saves typing, which multiplied among many programmers is efficient.

For me, it was one of those moments of mild disgust that coincided
with my discovery of Forth.  And the realisation that if code like
this Basic interpreter could make money, I'm set for life!

References:

1.  Microsoft Basic Decoded & Other Mysteries for the TRS-80, by James
Farvour, third edition, September 1981, page 8, input phase,
interpretation & execution.

-- James Cameron
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2014\05\28@075144 by Byron Jeff

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On Wed, May 28, 2014 at 09:29:26AM +1000, James Cameron wrote:
{Quote hidden}

Actually this sort of changes my mind on it (which is why I prefaced the
entire statement with "may or may not" to begin with...). Since tokens were
in a different space than values, it's trivial to determine that the first
token after an end is a variable if the top bit is not set.
That would make the LET redundant, and clearly occupying valuable space.

BTW I too wish that I had come across FORTH early on instead of 6 or so
years ago. I'm in the process of putting together a completely self hosted
FORTH development system for the PIC24F series of chips. It would have
saved me the trouble of trying to write my own tokenized C-like
cross-compiler oh so many years ago.

BAJ

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2014\05\28@085603 by Isaac Marino Bavaresco

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face
Em 28/05/2014 08:58, Byron Jeff escreveu:
> Actually this sort of changes my mind on it (which is why I prefaced the
> entire statement with "may or may not" to begin with...). Since tokens were
> in a different space than values, it's trivial to determine that the first
> token after an end is a variable if the top bit is not set.
>
> That would make the LET redundant, and clearly occupying valuable space.
>
> BTW I too wish that I had come across FORTH early on instead of 6 or so
> years ago. I'm in the process of putting together a completely self hosted
> FORTH development system for the PIC24F series of chips. It would have
> saved me the trouble of trying to write my own tokenized C-like
> cross-compiler oh so many years ago.


I too am in a pursuit for some sort of interpreted/scripting language
for embedded systems for a long time.

My motivation it to allow the users of my boards to customize their
operation or write their own routines. The problem is that I don't want
them to be able to run native code because it would allow someone to
steal my own code.
That protection could be done with dsPIC's CodeGuard, but it is not
available for other platforms, and I don't know how secure it is indeed.

Some years ago, I tried XPL0 (<http://www.xpl0.org/>). It is a language
created in 1976 by Peter J. R. Boyle and maintained by Loren Blaney.
There is a compiler that generates 80x86 code and another that generates
a psudo-code called I2L. The original I2L interpreter was written in
80x86 assembly and I wrote a very portable new one in C to use in my
boards. The performance was acceptable, although not great.
It worked, but I wasn't satisfied with the fact that it is one more
language to be learned and it is very obscure. That would prevent its
adoption by my customers.

I'm working now in a Thumb emulator written in C, that can be compiled
for a lot of platforms (even 8-bit, although the performance would be
awful). This emulator creates a virtual ARM processor (Thumb1
instructions only) that won't allow any access outside its private
memory pool. System calls, common library functions and other predefined
operations are implemented natively and called with the Thumb "svc"
instruction.

I managed to convince the ARM-GCC to generate code for this virtual
processor and it seems very promising. The user's applications can be
written in any language with a compiler that generates Thumb code.

Right now I don't have time to polish it, but I'm excited about the
possibilities.

Isaac




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2014\05\28@093147 by Byron Jeff

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On Wed, May 28, 2014 at 09:59:08AM -0300, Isaac Marino Bavaresco wrote:
{Quote hidden}

Isaac,

This is a back to the future post. It seems that you and I had just about
this same discussion a bit more than a year ago. Using the Googlenator on
"XPL0 I2L" brings up the thread as the 3rd hit.

BAJ

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2014\05\28@095449 by John Guillory

picon face
I was somewhat thinking how it would seem fairly easy in pascal, but then I started hashing things out and had to wonder a few things.  1. Your code will be in rom/EPROM/EEPROM, and you don't want someone stealing your code.  So where will the script be stored?  How will the user upload it?  Memory card?  I could possibly write it in a unit, but then you would need pic pascal to use it.  If I wrote it like a program, the only way it'd be valuable to you is if you use one pic to interpret the script and the other to do whatever you wanted to do.... I could actually see it having potential to even market something like that.  Put a memory card slot and pic chip on a card with pins to interface to your main board, and allow you to mount it on one side of a plastic case, and run a ribbon cable to your board.  
--
KF5QEO
John Guillory
spamBeGonewestlakegeekspamKILLspamyahoo.com
Cell: 601-754-9233
Pinger: 337-240-7890
Google Voice: 601-265-1307


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2014\05\28@133748 by William \Chops\ Westfield

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> Basic implementations on old (70s - 80s) computers were tokenizing Basic language before storing it in memory

If we're talking about the original BASICs at the time when LET may have become optional, we're not talking about the personal computer BASICs of the 70s to 80s.  We're talking about the timesharing system Basics of the 60s and 70s.  AFAIK, they didn't tokenize until you typed "run."

BillW

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2014\05\28@154337 by Bob Axtell

face picon face
Hi, John!

It is almost impossible to prevent your code from being stolen, regardless of the processor or scheme.

In the olden days, before we began living in glass houses, we ground off the programming pins after we programmed the PIC, but nowadays the code can be read by nefarious companies who probe the raw chip.

The entire chip fab process needs to be rethought such that the cost to steal code becomes excessive. Burying the actual chip layout under several silicon layers wouldn't hurt, as would obscuring key sections of the chip. Its possible that a thin insulating layer that also obscured anything below it might be enough, because any effort to break through the obscuring layer would cause the chip itself to be broken in the process..

--Bob A
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2014\05\28@170709 by Isaac Marino Bavaresco

flavicon
face
Em 28/05/2014 16:43, Bob Axtell escreveu:
> Hi, John!
>
> It is almost impossible to prevent your code from being stolen,
> regardless of the processor or scheme.
>
> In the olden days, before we began living in glass houses, we ground off
> the programming pins after we programmed the PIC, but nowadays the code
> can be read by nefarious companies who probe the raw chip.
>
> The entire chip fab process needs to be rethought such that the cost to
> steal code becomes excessive. Burying the actual chip layout under
> several silicon layers wouldn't hurt, as would obscuring key sections of
> the chip. Its possible that a thin insulating layer that also obscured
> anything below it might be enough, because any effort to break through
> the obscuring layer would cause the chip itself to be broken in the process.
>
> --Bob A


Hello, Bob!


It seems that your post was directed to me, not to John.

I know that it is possible to probe the chip directly and read the code.
Just my boards most probably won't attract that much interest, because
that type of attack is still costly and complex.

The protection I want is against the software-only hacker, that if
allowed to upload native code to my MCU, could write a simple routine to
output my code through a serial port. This type of attack is accessible
to any high-school kid.

For this reason I devised the sandbox/virtual machine solution. It ought
be faster than an interpreted language with a much smaller footprint
than a Java VM.


Isaac

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2014\05\28@212547 by Byron Jeff

flavicon
face
On Wed, May 28, 2014 at 09:59:08AM -0300, Isaac Marino Bavaresco wrote:
> Em 28/05/2014 08:58, Byron Jeff escreveu:
> I too am in a pursuit for some sort of interpreted/scripting language
> for embedded systems for a long time.
>
> My motivation it to allow the users of my boards to customize their
> operation or write their own routines. The problem is that I don't want
> them to be able to run native code because it would allow someone to
> steal my own code.

That's the one good thing about being an academic. Code is for students to
learn. Nominal value isn't that important.

> That protection could be done with dsPIC's CodeGuard, but it is not
> available for other platforms, and I don't know how secure it is indeed.

I looked at code guard for a different reason: protection from being
overwritten. Unfortunately my latest darlings, the PIC24FV families with 5V
operation and 20 and 28 pin DIP pinouts, only have basic protection. This
level is all or nothing in terms of protecting the flash.

It doesn't work for my FORTH interpreter because I wanted to use part of
the flash as a cache for the RAM between powerups. If there were a separate
boot segment, then the FORTH kernel could be protected while still allowing
for the flash cache to be readable/writable. Alas that's not possible since
it's all or nothing. So right now I'm operating with the code completely
open.

{Quote hidden}

Interesting idea.

BAJ

{Quote hidden}

-- Byron A. Jeff
Chair: Department of Computer Science and Information Technology
College of Information and Mathematical Sciences
Clayton State University
http://faculty.clayton.edu/bjeff
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2014\05\29@043814 by alan.b.pearce

face picon face
> > That protection could be done with dsPIC's CodeGuard, but it is not
> > available for other platforms, and I don't know how secure it is indeed..

Yes, it seems a shame that CodeGuard hasn't taken off, it seems a nice feature, rather like the memory protection mechanisms in mainframes, but applied to Flash memory.

{Quote hidden}

Maybe you need to look at the 24E/33E series, which have an auxiliary memory area designed for bootloaders. Only trouble is they are 3v3 devices, but have some 5v tolerant pins.

-- Scanned by iCritical.

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2014\05\29@145216 by Byron Jeff

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On Thu, May 29, 2014 at 08:37:03AM +0000, TakeThisOuTalan.b.pearceKILLspamspamspamstfc.ac.uk wrote:
{Quote hidden}

You completely summarized my reasons for sticking in the area that I've
been.

I think the alternative I may use for students is to completely lock down
the flash and have them add a SPI/I2C flash chip that can be used to hold
ram images and data blocks. The key is to up the reliability so that errant
code won't erase the kernel.

BAJ

-- Byron A. Jeff
Chair: Department of Computer Science and Information Technology
College of Information and Mathematical Sciences
Clayton State University
http://faculty.clayton.edu/bjeff
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