Sunday, September 15, 2013

Resurrecting APL\360

Back in 1973 I had my first introduction to a computer. I was in 7th grade and was looking through a list of clubs that we could join. Being the geek that I already was, I saw one that looked interesting - Computer Club. I remember being a little intimidated at the first meeting when it was me and a bunch of upper class-men. We were told that we'd be learning a computer language called APL and we were given a brochure that looked like this.
Inside there were a bunch weird of symbols that looked a lot like mathematics. 
We were brought down to a small office and introduced to the computer. It wasn't actually a computer, but a terminal which connected to a mainframe located some 25 miles away. It was connected to the phone line via an acoustic coupler. The terminal itself was an IBM 2741 that looked something like this. 
 It typed using the famous selectric type ball mechanism at an amazing rate of 10 characters per second (110 baud). The typeball looked like this. 
When running at full tilt it would whip this ball around and up and down and make a sound that I can remember to this day - almost like it was trying as hard as it could to express the thousands of calculations going on behind the scenes. The keyboard on the terminal looked like this
... with capital characters printed with unshifted keystrokes and and the funny symbols printed when shifted. During the next months of learning APL and playing with the computer I came to know these symbols very well and the ease with which one could express complex operations with just a very short expression. In fact,  the memory of APL would cause persistent frustration throughout my career when using other computer languages which required lines and lines of code to express the same thing which could be done with a vector here, some transformations there and wallah, the answer.
So that was 40 years ago now. Things have changed so much with computers, but this first experience with APL still intrigued me.  I searched the web to see what was out there about APL. I found many versions of APL that have been developed over the years based on this original, most running on Windows or Linux, some free and some required a paid license. But I also found this, Running APL\360 on OS/360-MVT 21.8F: MVT for APL Version 2.00. A group of people have resurrected the original APL\360 to run on an emulated IBM 360 system running OS/360 and MVT! And all this is available for free and can run on any Windows or Linux system.
I set out to get this system running on my home system. My first attempt was with Version 1.00 of the distribution. With very little experience with MVT, it took quite a few tries, but I eventually got it running. 
Here's a shot of the main operator console.
Here's a shot of a user session.
The symbols print very similar to the original APL typeball. All in all, the system is an exact operational replica of the original APL\360 with the exception of the 2741 terminal with its look, feel and noise.
Version 2.00 of the APL on MVS is now available and is much easier to install and run. Give it a try if you're an APL fan, especially if you were introduced to computers with APL\360 like me.

Wednesday, February 6, 2013

After the HP-41C

HP28C Opened
The HP-41C series remained as Hewlett Packard's top calculator for 8 years. In 1987, HP took a new direction and introduced the HP-28C, a graphing calculator with a new operating language called RPL. It featured the ability to enter and solve equations symbolically. The packaging also made a radical departure from the traditional slab style by replacing it with the so-called "clam shell" case. The left side of the case had an alphanumeric keyboard while the right side had the traditional scientific keyboard. The display was an LCD matrix which allowed to display either 4 lines of data or a graph.

The RPL programming language was not as intuitive as the former RPN. It came with two user's guides, totaling about 675 pages demonstrating the complexity of the calculator. This and the lack of ability to import or export programs limited the popularity of the model for programming development and sharing. On the other hand, its extensive built-in library of math, statistical, conversion and financial functions made it extremely powerful.
HP-28C Closed

Infrared Printer
Shown here (above and right) is a 28C that I found on eBay. Since the 28C was very quickly superseded by the HP-28S in 1988 having 4x the memory, the 28C does not fetch a very high price. This one was fully working with a good battery compartment (a common problem) and in otherwise good condition except for a blemish on the front cover.

The HP-28C had the ability to wirelessly connect to a printer via an infrared transmitter. Shown here (left) is one I found on eBay for not much. This model printer is still sold today to connect to HPs current graphing calculators.

HP enthusiasts were not happy with the move away from the intuitive RPN to RPL. To answer their concern, HP introduced in 1988 the HP-42s. This calculator was compatible with the HP-41C series but offered a more compact package and utilized a unique menu system which allowed to reduce the number of keys and the number of functions assigned to one key. While it had all the functionality of the earlier HP-41C, it lacked connectivity. It could not import or export programs and it could not connect with peripherals.

Free42 - an HP-42s Emulator for the iPad
With these two calculators, the HP-42s and the HP-28S, HP would start on a dual product line.  The former would be the traditional non-graphing RPN calculator with sequential programming. The later, a line of graphing calculators based on RPL. The HP-28S remained in production until 1992 when it was replaced by a more advanced graphing calculator without the clam-shell design, the HP-48 series. The HP-42s continued to 1995 with no real replacement. Other lower function RPN scientific calculators would follow, but the HP-42s remains among the most coveted calculators by HP enthusiasts. Prices on eBay start around $150 and go as high as $400 for boxed examples. For this reason, I don't have one of these (yet). I do however have an emulator app called Free42 that runs on my iPhone and iPad. It does everything that the original does, but for free!

Saturday, February 2, 2013

The HP-41C

Hewlett Packard took a while to come back with an answer to the Texas Instruments TI-59. They knew that a revolution rather than an evolution was needed. Their response came in 1979 with the HP-41C. This handheld calculator featured an alphanumeric display and continuous memory. No longer was it necessary to have a magnetic card reader to save programs. The alphanumeric display made it possible to prompt for input and to display results with meaningful labels. It also made programming easier as the instruction mnemonics could be displayed rather than key positions. Also, rather than having multiple shift keys and multiple functions per key, functions could be selected by spelling out their mnemonics.  The calculator proved to be very popular and was sold by HP all through the 1980's

I never had one of these back in the day. I considered buying one in college, but I was unable to sell my SR-52 and couldn't afford the $295 price tag. The one shown here is an HP-41CV which was an upgraded model introduced in 1980. I found it on eBay in 2012. It had some broken screw wells and some corroded contacts which prevented all the expansion slots from working. It has been repaired and is now fully functional.
A key feature of the calculator was that it was more than just a standalone unit, it was a platform for expansion. It featured four ports on the top of the unit which would accept ROM pacs and other accessories. ROM pacs could be purchased that contained programs targeted for specific markets like business, math, physics, surveying, etc. Other pacs expanded the programability features of the calculator or added memory capacity.

Shown here are 3 ROM pacs installed. The X Functions pac adds more functions to the calculator. The X Memory adds memory and the Math pac adds Math programs.

Another expansion feature of the unit was an I/O port on the side which allowed more advanced peripherals like plotters, data acquisition equipment, etc to be connected. This made the calculator popular among many specialized engineering and scientific disciplines.

Even though a card reader was no longer necessary, one was available as an option to allow to free up memory for new programs while saving older programs for later use. The card reader unit attached to the top of the calculator using one of the expansion ports. The magnetic cards used were the same as those used by the HP-67 and in fact the unit had the capability to convert the HP-67 programs to HP-41C programs.

When attached it made the calculator somewhat long and unwieldy, but it could easily be removed when not in use.

The reader shown here was found on eBay, not working. The same design for the reader mechanism was used as the HP-67 so it suffered from the same "gummy wheel" problem whereby the rubber wheel driving the cards through the reader would turn to sticky gum. This one also had a bad transistor which I replaced. It is now fully working.
For the HP-41C series, HP decided to have an attachable printer. Luckily they made the unit much more compact and attractive than TI's PC-100A. It easily attaches into one of the 4 expansion ports on the top of the calculator.

The one shown here was found on eBay and was fully working (for once!). It just needed some cleaning

The eBay purchases luckily came with all the associated documentation and boxes which is unusual. I also have the original calculator case (not shown).

Thursday, January 31, 2013

The TI-59

The TI-59 was Texas Instrument's successor to the SR-52 and answer to the HP-67. It came out in 1977, just after I bought my SR-52, of course. It quadrupled the number of program steps and added ROM program modules. It still did not have constant memory so that every time you turned it off, you lost  your program. Thus it still featured a magnetic card reader. The cards were not compatible with the SR-52. 
The TI-59 was TI's top of the line calculator until it was discontinued in 1983, although it became less relevant in 1979 when the TI-58C was introduced which had constant memory and cost much less. In 1983 both were replaced by the TI-66.
I never had one of these back in the day since I had already committed to the SR-52. Currently, these calculators are not as desirable as the old HP's and they can be found cheap on eBay. This one is the product of two eBay purchases used to produce one fully working example. 

The PC-100A printer cradle and charger was introduced with the SR-52. It was larger and clunkier than the HP-97 combined package, but it had the advantage that you didn't have to buy two expensive calculators to have both a desktop and a portable programmable calculator. 
This example was not working when I bought it on eBay, but I was able to repair the printer. I also swapped out some parts from another non-working one to produce one that is both clean and working. The paper it uses is a non-standard size but I was able to find new blank rolls from a guy in Romania (also on eBay).
I accumulated a few accessories including a case, blank program cards, Master ROM pac and also the Leisure ROM pac.

Tuesday, January 29, 2013

SR-52 vs. HP-67

Before there was iPhone vs. Android. Before there was MAC vs PC. Before there was IBM vs Microsoft. There was Texas Instruments vs. Hewlett Packard. In 1976 I was in the market for a calculator and the two top-of-the-line calculators were the SR-52 from TI and the HP-67 from HP. Both were fully programmable and came with a magnetic card readers that allowed to store and load programs. I ended up getting the TI, mostly because it was cheaper. The two brochures shown here are ones that I used to help make my decision.

The first fully programmable calculator with program storage was the HP-65 introduced by HP in 1974 with an MSRP of $795. TI came with a response in 1975 - the SR-52 with a price tag of $395. Here's my original, purchased in December 1976 when I was a sophomore in high school.  I used this calculator all through high school and college and it served me well.
After years of sitting, the battery compartment corroded and the card reader stopped working. After more years the calculating unit itself fried and started to answer with jumbled displays.
I set out recently to restore it. Repairs included a rebuild and tuning of the card reader, rebuild of the battery pack and replacement of the main processor board (from a donor calculator). It now is fully working.

 I still have all the original stuff that came with the SR-52 including the Game pac and blank magnetic card pac. Original sales receipt too from 47th Street Photo, December 8th, 1976 showing a big discount off of retail price!
 The HP-67 was introduced by HP in 1976 in response to the SR-52. It bettered the specs and also had the well respected HP engineering and design. Big difference was that it was RPN instead of Algebraic entry.  If I had the resources back then, I probably would have picked it over the TI, but it cost twice as much - $450 - and this price was never discounted.
The  one shown here I purchased recently on eBay. Actually, I bought two of them and chose the best parts from both to make this one. Both of them needed the card reader repaired. I ended up selling the other one for enough to pay for both.

Here are some HP-67 accessories including a leather case (which is really from an earlier HP-65), an owners manual, a charger and the Standard Pac of magnetic cards. The charger needed a power transistor replaced.

 The companion to the HP-67 was the HP-97. It has the same capability but with a built in printer and larger keys and display. New, this cost $750 back in 1976. I found this one on eBay. It needed a thorough cleaning, painting and the printer and card reader repaired. Now it's fully working.

Accessories that I have for the HP-97 include case, charger, owners manual and Standard Pac manual.

Finally, a picture showing both HP-67 and HP-97 together, just like in the brochure.