IBM 5140 - a blast from a past

[Adventurer]

Today I opened the back of the machine - to look for possible problems in Power Supply Unit. Again, I must admit I like how simply it is possible to remove components here - just 4 screws, taking off the back plate, and pull out power supply board - no hidden cables or secrets here, it just comes out:

Now, floppy drive cables, attached to the floppy drives, are visible on both sides, battery compartment in the middle, and modem board on the right. Power supply board looks clean and nice, but there can be a problem hidden:

Capacitors here:

And even more capacitors there:

None of them show any obvious visual signs of leaks, but as we all know, dead capacitors are not always leaking something visible. Anyway, 30 years old capacitors could cause unstable voltages or voltage spikes from PSU, resulting in failures. All I could check was battery charging voltage near battery connection socket, it was 14.91-14.92 volts, which drops to around 11.9 volts with battery connected. No voltage spikes there.

On-off switch working properly, shows 0 Ohms resistance between pins when pressed, this does not seems to be responsible for any problems mentioned.

If I only had a spare IBM 5140, problems could be traced much easier - just replacing modules would allow to detect the problems. RAM suspected - replace. Mainboard? - replace. PSU? -replace. Another option would be to test each capacitor on PSU and replace faulty ones, but I do not have a tester for them (yet).

At least now I can use IBM original power adapter - this one is not causing any problems for sure.

Anyway, I assembled back the machine, was greeted with a long beep on switching it on, second time again, and then it started to work as usual, with Parity Checks as usual, and dissapearing after trying to set the time several times in a row. I'm back where I started.

Still, I have not given up the hope to restore this Macbook Air of 80-ties to it's complete functionality. Using it with Parity Checks is like driving a car with "engine check" light on - can be done, but not reccomended, and sooner or later it will need to be serviced anyway...

 

[Adventurer]

While dealing with the Convertible's technical problems, I decided to compare two computers of the same era - Tandy 102 and IBM 5140. Despite running different hardware, they have many things in common. Both are made at the same time - in fact, living in 80-ties you could be thinking hard, what system to choose - fully XT compatible IBM convertible, or much cheaper, lighter, but less compatible Tandy 100/102 or one of it's sibblings - Nec PC 8201 or Olivetti M10. However, when putting both of them head to head, it becomes clear why IBM 5140 was loosing the fight.

First, similarities:

Both machines have great keyboard, and I really mean great - mechanical switches are much better for typing and give more tactile feedback than membrane keyboards, which are on most today's machines. Typing text on them is fast, reliable, and "clicky", which reminds a bit of typewriter sound.

Both are laptops of that era, and both have batteries. The main difference is Tandy 102 can use simple AA batteries, but IBM needs to use Ni-CD battery pack designed for this model.

Both have no hard drives - although there is a difference - Tandy 102 uses part of RAM for document storage, IBM Convertible - 720K floppy drive. However, an external floppy drive was available for Tandy 102, allowing of total 200K storage on a single floppy.

Both could be used for Word processing - although IBM Convertible could run "full size" desktop applications, there was third party software support, with additional programs stored on ROM chip.

Both have limited size for a document file. While maximum file size for Tandy 102 is about 30K, which is limited by free memory, IBM Convertible is not much better when it comes to larger documents. For example, IBM Notewriter, which was included in startup floppy, allows only 12K maximum size. There was an option to use PC-Write, which allows only 60K maximum file size.

Both need to transfer data to "bigger" machines - although it is more important with battery backed memory of Tandy 102, IBM Convertible with it's limited floppy storage and rather picky floppy drives was not reliable as a data storage machine.

Both can use modem for data transfer - was important at that time for journalists and writers, who needed to upload text to remote machine for storage or printing, using wired technology of that era - a phone line.

Both have built in BASIC, however, Tandy uses Basic for setting system time, calendar, date, and perform file operations, but IBM convertible uses it only for proframming - you can not control system functions from built in Basic.

Both can be connected directly to a printer. If anyone would want it, you could use either machine as full desktop system, with additional, usually expensive accesories.

Now, the differences:

IBM convertible is much larger, and much heavier machine. Even four Tandy 102 will weight less than almost 6 kg's heavy IBM "laptop". IBM however still tried to market their machine as a portable device, even making advertisement photos of smiling college girl holding the machine on her lap. This impressed some parents, who bought the expensive machine for their grown up kids, and they had to haul this beast from one classroom to another.

IBM convertible has much larger screen, and it displays compressed, but still, and 80 column wide text - Tandy 102 can display only 40 columns wide text. Screen height is much better on Convertible as well - 25 lines vs just 4 on Tandy 102.

Screen quality is another issue - although much larger, Convertible's screen readibility is poor. Even later, backlit model has problems with it - it has great readability in subdued light, but in bright light screen contrast is too poor to be comfortable for reading. Tandy 102, on the other hand, has great non-backlit CD, which is perfectly readable outdoors, and even indoors, usually not requiring a direct light source for a good readability.

Autonomy - although IBM Convertible can run for impressive 8 hours on a new battery, it is no much for Tandy 102, which can go over 20 hours, and all you need is a set of 4 AA batteries to keep it ticking. Compare it to hauling around heavy AC battery for IBM convertible, and then guessing - how much time do I need for a battery to be charged? There is no battery indicator on Convertible, you never know when battery has fully charged. You never know how much is left, until the very end, when the machine gives beep s, when it is about to be dead. Tandy 102 was much better suited for off-grid operations than IBM, all you need was extra AA batteries.

Reliability - IBM convertible is more complicated machine with more moving parts, which are more likely to fail than Tandy 102, with keyboard as the only moving part in the machine. You could easily drop a Tandy on a floor, pick it up and continue working. You can easily break an IBM Convertible the same way, which appears well made, but it's own weight will work against it if dropped.

Expandability. Tandy 100 has built in printer port, RS232 port. Two ports you really needed at that era. IBM convertible has none. Only if you would shell out more money, and buy an additional expansion unit, you could be happy, but poor owner of IBM Convertible with serial and printer port. Even poorer, if you decided you would need an external monitor, and appropriate video output module for an IBM.

Pricing. You could buy at least 3 Tandy 100 computers for price of one IBM convertible. Even buying external storage cards and floppy drive would still allow to buy two Tandy 100 with accesories for single IBM convertible without any, even COM port.

 

[lowen]

While dealing with the Convertible's technical problems, I decided to compare two computers of the same era - Tandy 102 and IBM 5140. ...

A more direct comparison would be to the Tandy 1400LT or 1400FD, which is very similar to the 5140 in specs. In fact, the 80s-vintage 1400LT is very very similar to the 5140, and might even be more bulky.

The Tandy 100, 102, and 200 (and their parent machine) were in a class by themselves, and were not 'PC Compatibles' like the 5140 and the Tandy 1400.

 

[Adventurer]

A more direct comparison would be to the Tandy 1400LT or 1400FD, which is very similar to the 5140 in specs. In fact, the 80s-vintage 1400LT is very very similar to the 5140, and might even be more bulky.

The Tandy 100, 102, and 200 (and their parent machine) were in a class by themselves, and were not 'PC Compatibles' like the 5140 and the Tandy 1400.

I was comparing them from usability standpoint - Tandy 100 as another class system was in fact fully capable of doing work, almost the same as PC-Compatible models, and for a lpwer price. Besides, I do not have a Tandy 1400 (yet)

 

[krebizfan]

Reviews at the time considered the 5149 to be less effective than the Toshiba T1100 which was released a few months before. Toshiba only had 1 floppy drive but upped the RAM to 512k. Toshiba weighed 4 pounds less and had a full array of ports. Forget ultraportables, the PC Convertibles were a mediocre entrant in the 808x portable market.

 

[kyodai]

If you look at how bulky the IBM is it is hard to believe that just 2 years later (1988) NEC released the "UltraLite" which - at A4 size and a bit over 2Kg weight - set the mark for lightweight notebooks. Coming with a backlit monochrome CGA display at full 640x200 resolution, built-in 2400 Baud modem, 8 MHz NEC V30, RS-232 serial port, 640 KB RAM, 2 MB RAM Drive, DOS 3.3 in ROM, SRAM card slot. It was soooo impressive back in the days and pretty much all journalists and writers wanted one so badly.

Just one year later the Poqet PC came out, rendering the Ultralite a bulky and heavy opponent.

Back in the days you sometimes had the impression that in the 1990s we would probably soon have holodecks and wristwatch computers with SVGA resolution screens.


Maybe you should make a comparison between the IBM Convertible vs IBM PC-110...

 

[Adventurer]

If you look at how bulky the IBM is it is hard to believe that just 2 years later (1988) NEC released the "UltraLite" which - at A4 size and a bit over 2Kg weight - set the mark for lightweight notebooks.

Well, it is true, however, it did not have that great keyboard, and had only external optional floppy drive. At least for me, I prefer non-standard looking machines, which were often underdogs even when they were produced. They all have something different, a different idea or design. Even if it was not really succesful, it is interesting as a collector's item.

Meanwhile, my writing setup is ready. I decided to use the machine despite it's flaws. Pc-Write works well, and hotkeys F1,F3 allow to save a document even if all I see is parity check. However, now the machine seems to become more stable, and setting time no longer causes parity check:

Tried to connect LPT printer - the oldest I have is Minolta PagePro 1100. At least now I can confirrm that LPT port works correctly, however, it does print only first line of text - I guess I need to install and configure DOS drivers first. Next task would be to find cheap donor machine to get rid of Parity Check (easier said than done).

 

[Chuck(G)]

If you were IBM in 1985 or so, the only relevant question when evaluating competition was "Will it run Lotus 1-2-3?" Really.

That why IBM pirated a 5.25" copy 1-2-3 to run for their PS/2 launch announcement (at the time, 1-2-3 was copy-protected). Lotus at the time, did not offer 1-2-3 in 3.5" media.

So, I'd couch any comparisons in those terms.

 

[kyodai]

If you were IBM in 1985 or so, the only relevant question when evaluating competition was "Will it run Lotus 1-2-3?" Really.

That why IBM pirated a 5.25" copy 1-2-3 to run for their PS/2 launch announcement (at the time, 1-2-3 was copy-protected). Lotus at the time, did not offer 1-2-3 in 3.5" media.

So, I'd couch any comparisons in those terms.

I guess that explains why my dad used Multiplan on our family computer (286 with lovely Hercules monochrome screen). I actually liked the column naming of Multiplan better because they used simple numbers for them. Besides that Multiplan was rather cheap... I guess it was also easier to copy... XD

@Adventurer: Why not show some love and use Word Perfect? I always thought of Word Perfect being one of the best writing programs of the 1980s...

Not a fan of old printers here, but maybe just a problem with the line feed characters i guess?

 

[Adventurer]

@Adventurer: Why not show some love and use Word Perfect? I always thought of Word Perfect being one of the best writing programs of the 1980s...

Not a fan of old printers here, but maybe just a problem with the line feed characters i guess?

The problem is I need a program, which saves as close to plain text format as possible. Since I'm using diacritical marks for my language, I need to run the file through text conversion program to be correctly readable in Windows. Already tried Wordstar 4.0 before - although it worked fine, the file format was unusable later. I can try to use WordPerfect, but I strongly suspect there might be similar problem as with WordStar as well.

As for the printer - even managed to get a driver, but it does not seems to work with CGA display, it just crashes on launching.

 

[kyodai]

Hm, so you have a codepage to use your language characters in DOS/CGA? Or does Wordstar come with these? Or do you use kinda escape characters?

To convert old DOS wordstar or WordPerfect documents to use in Windows you will need to convert them. I think Microsoft Office 95 came with a WordStar converter, but obviously it was dropped later on.


For an LPT printer I am surprised you need a driver at all. Did you try something like "Type MYDOC.TXT > LPT1"? At least for ASCII based Text files that should work fine, make a small test file in EDIT and print it that way. Normally 99% of all printers should be able to handle that.

 

[Scali]

Hm, so you have a codepage to use your language characters in DOS/CGA?

CGA has a fixed character ROM, and cannot make use of alternative codepages. You'll need EGA or better.

 

[Chuck(G)]

I guess that explains why my dad used Multiplan on our family computer (286 with lovely Hercules monochrome screen). I actually liked the column naming of Multiplan better because they used simple numbers for them. Besides that Multiplan was rather cheap... I guess it was also easier to copy... XD

There was a real battle among spreadsheet programs back in the day. I'm responsible for a fair amount of code in SuperCalc (both 8 and 16 bit versions), myself. But if you were with any of the big finance firms, the standard was 1-2-3.

 

[Adventurer]

Hm, so you have a codepage to use your language characters in DOS/CGA? Or does Wordstar come with these? Or do you use kinda escape characters?

To convert old DOS wordstar or WordPerfect documents to use in Windows you will need to convert them. I think Microsoft Office 95 came with a WordStar converter, but obviously it was dropped later on.


For an LPT printer I am surprised you need a driver at all. Did you try something like "Type MYDOC.TXT > LPT1"? At least for ASCII based Text files that should work fine, make a small test file in EDIT and print it that way. Normally 99% of all printers should be able to handle that.

Well, all I have is a custom DOS language driver, but for obvious reasons I can not use any special font under CGA. Characters are not displayed correctly on the screen, however, I can later convert it to Windows codepage on another computer, and my diacritical marks are in place as should be, as the encoding itself is correct.

For me, the best way is DOS text -> Windows text (CP1257) -> Text processor (MS Word).

If I do it other way, there is a risk of conversion problems after importing WordPerfect or Wordstar documents in modern text editor. Besides, I really do not need any formatting features for writing. All of it can be done later on a more modern machine.

As for printing - the command works, however, it only prints one line. I can do nothing about it yet, this is why I tried Minolta DOS driver, which does not work under CGA. I guess this one belongs to the 1% not working without a special driver

 

[paul.brett]

I'm responsible for a fair amount of code in SuperCalc (both 8 and 16 bit versions), myself.

Supercalc 4 rocked!

 

[Chuck(G)]

CGA has a fixed character ROM, and cannot make use of alternative codepages. You'll need EGA or better.

I don't know what's in the 5140, but the plain old PC CGA had an 8KB character generator ROM with only half used (A12 is tied high). One could always burn one's own version. Not that CGA characters were any great shucks, compared to the MDA set.

 

[Scali]

I don't know what's in the 5140, but the plain old PC CGA had an 8KB character generator ROM with only half used (A12 is tied high). One could always burn one's own version. Not that CGA characters were any great shucks, compared to the MDA set.

Well yes, you can replace the physical ROM chip on the card. But the DOS codepages will upload a new font to your videocard, if it supports it (EGA or higher), on-the-fly.
This allows you to dynamically load a codepage for your specific country/region, whereas CGA/MDA were sold with a particular ROM, and that's what you had to use (or modify the ROM chip, as said... but you couldn't just load whatever codepage you wanted from your config.sys).

 

[kyodai]

Well, all I have is a custom DOS language driver, but for obvious reasons I can not use any special font under CGA. Characters are not displayed correctly on the screen, however, I can later convert it to Windows codepage on another computer, and my diacritical marks are in place as should be, as the encoding itself is correct.

For me, the best way is DOS text -> Windows text (CP1257) -> Text processor (MS Word).

If I do it other way, there is a risk of conversion problems after importing WordPerfect or Wordstar documents in modern text editor. Besides, I really do not need any formatting features for writing. All of it can be done later on a more modern machine.

As for printing - the command works, however, it only prints one line. I can do nothing about it yet, this is why I tried Minolta DOS driver, which does not work under CGA. I guess this one belongs to the 1% not working without a special driver

Well yeah I'm not that much of a language crack, but at least i can speak some German, French and Japanese. Well for German and French the CGA codepages displayed the special characters "considerably" well, for Japanese you'd need crazy hacks to have Kanji displayed properly - the huge interest in the HP 200LX (Japanese like small computers) helped developing a CGA character scene. Let's not talk about Kanji input in DOS, that is even worse than displaying these characters...

I had some documents converted from WordPerfect 5.1 to Office 95 and that worked really well. I still had some old WordPerfect docs on floppy when i first used Office 97 and i was soooooo pissed that they got rid of the WordPerfect converter.


That the command only outputs the first line puzzles me since all it does is doing a straight pipe to the LPT port - so why should the printer give up after one line? I've used so many different printers back in the days but "type xy.txt > LPT1" was my usual way of printing and it never failed. Back in the days that was how i usually printed manuals or cheat sheets for popular games that i downloaded from mailboxes. Minolta must have put som evil magic in their printers...

 

[Chuck(G)]

I read some Lithuanian, and I believe the character sets are similar. The problem is that the standard 437 (CGA) character set lacks a number of characters with diacritical marks, notably csz with caron, aeiu with macron, gkln with cedilla. That's all that comes to mind amidst a misspent youth designing a Teletext/Videotex-compatible terminal.

There's also translit and Pokemon encodings, but they look weird to these old eyes.

 

[Adventurer]

I read some Lithuanian, and I believe the character sets are similar. The problem is that the standard 437 (CGA) character set lacks a number of characters with diacritical marks, notably csz with caron, aeiu with macron, gkln with cedilla. That's all that comes to mind amidst a misspent youth designing a Teletext/Videotex-compatible terminal.

There's also translit and Pokemon encodings, but they look weird to these old eyes.

Well, the character set is similar to Lithuanian and Latvian languages. To have full support for my language, I need at least EGA display. However, it would force me to use only newer machines. This is why using driver without fonts work fine with me, it is not so big deal as I thought - all I need to remember is the sign or symbol for diacritical characters, and then I can easily read or even edit the text I've written.

For other machines with no language support, such as Tandy 102 I use translit, and then convert it to normal text - works fine as well.

Meanwhile I'm starting to get error 0172 on restart. Pressing F1 allows the computer to boot. All I could find from diagnostics code was: "Rolling bit test failure on NVRAM diagnostic byte". Does that makes diagnosing the problem easier?