Subject: IBM 5100 tinkering

From: Hans Pufal <[email-masked]>
Date: Sun Jul 13 19:34:21 2003

We did some tinkering with our IBM 5100 the other day with results which 
might be of interest.

Our 5100 is a model A4; it has 64Kbytes of memory and APL (only).

When we opened up the beastie for a service a year or so ago and 
speculated on the fact that there were no empty slots in the card cage 
(we do seem to have every built-in option made) which led us to propose 
that perhaps the BASIC interpreter was also included but made 
unavailable by the absence of the language selector switch on the front 
panel.

Examining the cable harness behind the panel showed a particularly thick 
section encased in insulation tape just behind where the language select 
switch would be installed and tempting evidence of one, possibly two 
unconnected wires.

At that time we went no further.

This week we were prompted to revisit the 5100 with a view of seeing if 
we could in fact run BASIC. Carfully cutting open the insulating tape 
around the cable harness behind the language select switch position 
revealed two unconnected wires complete with tiny push on connectors.

We jumpered the two wires, powered on the machine and waited with bated 
breath. Following the familiar self-test display we were presented with 
an unfamiliar prompt, not the APL one at all. A little fiddling with the 
keyboard quickly confirmed that we had BASIC operational!

So at least the APL only versions of the 5100 are configured with the 
BASIC interpreter which is disabled simply by the absence of the 
language select switch. Our IBM engineer speculates that the reverse is 
not the case : the BASIC only configuration does not include the APL ROM 
code. Anyone care to experiment and confirm that?

We are now installing a language select switch (though alas not of the 
same type as the others) and look forward to playing with BASIC on the 
machine.

Does anyone know the price difference between the A4 and C4 models? I 
would hazard a guess that that switch cost several hundered dollars at 
least ;-)

Oh, what prompted us to revist the 5100? We recently acquired a 
Commodore PET 2001 and on compiling some techinal notes for it found a 
web site stating that the PET was 2 to 3 times faster than the 5100. 
That statemnet surprised me and I wanted to confirm it.  Early 
indication show that the two machines are remarkably alike in 
performance (another suprise) the following program runs in the same 
time (to the second) on both machines :

     10 a = 0
     20 print a, a*a, sqr(a)
     30 a = a + 1
     40 if a < 100 goto 20
     50 stop

The 5100 seems about 30% faster on though with the following program:

     10 a = 0
     20 b = a*a
     25 c = sqr(a)
     30 a = a + 1
     40 if a < 100 goto 20
     50 stop

So it seems it is the display which slows it down.

Regards,

   -- hbp

---

From: "J.C. Wren" <[email-masked]>
Date: Sun Jul 13 19:58:00 2003

I'm not sure what video controllers the PETs used, but Motorola 6845 type 
controllers had a register that set the starting scan address of the video 
memory.  So scrolling was as easy as changing this pointer.

	IBMs have always scrolled by doing screen copies.  I don't know if you 
remember Xenix, but Xenix used to scream on a Hercules graphics card.  That 
was because they used a similiar technique, and weren't limited to the BIOS 
implementation.

	I wonder if the difference in speed you are seeing is a result of this type 
of comparison?

	--John

---

From: "Hans Franke" <[email-masked]>
Date: Thu Jul 31 12:57:01 2003

> So it seems it is the display which slows it down.

Well, to some extend. To my experiance it's rather the PET who
slowed down the programm. The PET had realy one of the slowest
BASIC interpreters / Systems around at that time. An Apple II
did usualy outperform it by some 30-50% with exactly the same
coding.

Gruss
H.

And back from KFest.

--
VCF Europa 5.0 am 01./02. Mai 2004 in Muenchen
http://www.vcfe.org/

---

From: hansp <[email-masked]>
Date: Thu Jul 31 20:37:36 2003

> did usualy outperform it by some 30-50% with exactly the same

Interesting. We are told that the PET BASIC is in fact a version of 
microsoft BASIC which was an outright sale with no royalties. Can anyone 
confirm/deny that?

We have a number of working BASIC machines of that era and plan on doing 
a grand performance comparison one of these days.

  -- hbp

---

From: Guy Sotomayor <[email-masked]>
Date: Thu Jul 31 21:27:00 2003

> So it seems it is the display which slows it down.

Before you jump to that conclusion, remember that "print" does a fair
amount of processing to put the numbers into EBCDIC (for the IBM anyway
-- but ASCII would be similar) as you are dealing with "floating point"
(it also does *some* column formatting as indicated by "," as opposed to
";").
-- 

TTFN - Guy

---

From: Joe <[email-masked]>
Date: Fri Aug 1 12:32:00 2003

>a grand performance comparison one of these days.

   I have an Intel MDS-800 (8080) and BASIC-80 if you want to benchmark it.
How are you timing these things anyway?

   Joe

---

From: Bob Shannon <[email-masked]>
Date: Fri Aug 1 18:34:00 2003

I could run some benchmarks using HP's 1968 HPBASIC if needed.

hansp wrote:

> Hans Franke wrote:
>
>>> We did some tinkering with our IBM 5100 the other day with results 
>>> which might be of interest.
>>
>>
>>
>>>     10 a = 0
>>>     20 print a, a*a, sqr(a)
>>>     30 a = a + 1
>>>     40 if a < 100 goto 20
>>>     50 stop
>>
>>
>>
> microsoft BASIC which was an outright sale with no royalties. Can 
> anyone confirm/deny that?
>
> We have a number of working BASIC machines of that era and plan on 
> doing a grand performance comparison one of these days.
>
>  -- hbp

---

From: "Rick Bensene" <[email-masked]>
Date: Sat Aug 2 00:03:00 2003

I'd be happy to try benchmarks out on:

A) TRS 80 Model 100  (MS BASIC)
B) HP 9830  (HP BASIC subset)
C) Tandy 600 "Laptop" (MS BASIC)

Rick

> -----Original Message-----
> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of Hans Franke
> Sent: Thursday, July 31, 2003 10:54 AM
> To: [email-masked]
> Subject: Re: IBM 5100 tinkering
> 
> 
> Well, to some extend. To my experiance it's rather the PET 
> who slowed down the programm. The PET had realy one of the 
> slowest BASIC interpreters / Systems around at that time. An 
> Apple II did usualy outperform it by some 30-50% with exactly 
> the same coding.
> 
> Gruss
> H.
> 
> And back from KFest.
> 
> --
> VCF Europa 5.0 am 01./02. Mai 2004 in Muenchen http://www.vcfe.org/

---

From: hansp <[email-masked]>
Date: Sun Aug 3 01:49:01 2003

OK, there seems to be a certain interest in running some benchmarks.

Back in 1977 Kilobaud published a set of BASIC benchmark programs and 
the following year PCW (in the UK) updated them. I have put up a set of 
pages at : http://www.aconit.org/hbp/BasicBench/ based on a 1982 PCW 
article. There is also a submission form if you want to measure your 
system(s).

  -- hbp