HP 75

[John W Kercheval]

Out of just general curiosity. Is anyone regularly using an HP-75? If so what are you using it for?

I love my 71B- it runs a lot o things, including all of the HP41 software. The 75 has a larger more luxurious layout but I've always wondered about its real world usability. Back in the 80s, in the Berkeley store we only sold 1 75. But a lot of 71s.


John

[Sylvain Cote]

(02-14-2015 12:57 PM)John W Kercheval Wrote:  Out of just general curiosity. Is anyone regularly using an HP-75? If so what are you using it for?

I love my 71B- it runs a lot o things, including all of the HP41 software. The 75 has a larger more luxurious layout but I've always wondered about its real world usability. Back in the 80s, in the Berkeley store we only sold 1 75. But a lot of 71s.


John

Hello John,

Yep! me. 8-)

I own several of them.
My two standard configurations are:
1) HP-75C/D + 8KB RAM + I/O-ROM + Math
2) HP-75C/D + 8KB RAM + I/O-ROM + Math + ExpansionPod
Both leaves me with 1 free port for other modules.

Today, I do most of my HP-IL tests with it. (along with my 41's and 71's)
The unit is fast and the keyboard, altough not perfect, is very good for typing.

Back in the 80's, I had the first configuration with the visicalc & text formatting modules,
the 82163A/82912A video display, the 82905B impact printer and the HP-7470A plotter.

I used it for math exploration, document writing, spreadsheet, agenda and as an instant problem solver.
It was also the machine where I learn the Forth language using the John Cassady implementation.

At the time I also had an Apple II setup (AppleII+Z80+80Col+FloppyDisks+Monitor+Printer+Softwares)
that was used basically for the same thing as my HP-75 setup.
The main reason I was using the 75 more often was the instant on/ready of the unit.

I also bought the HP-71B upon released, but I used the unit to control electronic labs,
remote devices and of course as an advanced calculator.

So in summary, the HP-75C was my general computing device
compared to my 41's/71's who was used as calculators and HP-IL controllers.

Best regards,

Sylvain

[John W Kercheval]

Thanks for the info!

It was the HP 41/71 Translator Pac that really moved the 71s back in our college computer store.

I do remember Visicalc! I guess you uysed it with the 75 interfaced to a TV screen? Right? i mean running that with 1 line may be hard.

Thanks again!

JK in NYC

[Sylvain Cote]

(02-14-2015 02:44 PM)John W Kercheval Wrote:  I do remember Visicalc!
I guess you uysed it with the 75 interfaced to a TV screen? Right?
i mean running that with 1 line may be hard.

Right, although it could be use on the 75 only, with the video it was much better.

Here two pictures that shows it ...
HP-75C Handheld Computer
HP-75 VisiCalc Module
HP-82912A 9" Composite Monochrome Monitor
HP-82163A 32 Columns x 16 Lines Composite HP-IL Video Interface
MC-00701A 80 Columns x 24 Lines Composite HP-IL Video Interface

Sylvain

[John W Kercheval]

One word:

Superlative

It is too bad the 75 never took off.

[rprosperi]

(02-15-2015 02:10 PM)Sylvain Cote Wrote:  

(02-14-2015 02:44 PM)John W Kercheval Wrote:  I do remember Visicalc!
I guess you uysed it with the 75 interfaced to a TV screen? Right?
i mean running that with 1 line may be hard.

Right, although it could be use on the 75 only, with the video it was much better.

Here two pictures that shows it ...
HP-75C Handheld Computer
HP-75 VisiCalc Module
HP-82912A 9" Composite Monochrome Monitor
HP-82163A 32 Columns x 16 Lines Composite HP-IL Video Interface
MC-00701A 80 Columns x 24 Lines Composite HP-IL Video Interface

Sylvain

Very cool Sylvain, thanks for posting these shots. I would not have guessed it's so usable this way. I experimemted with VisiCalc when I got a 75C with this ROM last year, and found it almost unusable with 1-line display as John noted. Did the display provide a full-screen image with the Text Editor module as well?

[Sylvain Cote]

(02-15-2015 03:12 PM)John W Kercheval Wrote:  One word: Superlative

I had to research this word, first time I had seen it.
There is a french equivalent to it, but I never heard it either.
Glad you like it. 8-)

(02-15-2015 03:50 PM)rprosperi Wrote:  Did the display provide a full-screen image with the Text Editor module as well?

The module is not called "Text Editor" but "Text Formatter".
The modern equivalent for this module is LaTeX.

Basically you use the text mode of the hp-75,
you enter your text in a text file with the markup tags defined
for the module, then run your file through the text formatter
program to generate the printable format for a specific printer.

I have started to write a full screen text editor compatible with the
HP-75 and the HP-71 about a year ago, but I never had time to finish it.
I will post it here when it's done and no time frame is specified here ;-)

Best regards,

Sylvain

[TASP]

My 1991 EduCALC HP41/71/IL flyer shows a special deal;

buy either a 9114 disc drive or a Thinkjet for $199 and $129 respectively and get an HP75D with wand, expansion pod and extra 8k ram for $90

Buy both the drive and printer and get the 75D package FREE.

I don't know how many they sold, but I took the deal. I used the Thinkjet far more than the drive or 75.

[Dave Frederickson]

(03-04-2015 01:18 AM)TASP Wrote:  My 1991 EduCALC HP41/71/IL flyer shows a special deal;

buy either a 9114 disc drive or a Thinkjet for $199 and $129 respectively and get an HP75D with wand, expansion pod and extra 8k ram for $90

Buy both the drive and printer and get the 75D package FREE.

I don't know how many they sold, but I took the deal. I used the Thinkjet far more than the drive or 75.

While you can still get ink cartridges for your ThinkJet, nowadays your printer and disc drive are better off on the shelf as collector's items. Many folks here have gone virtual with the PIL-Box, an HP-IL to USB interface by J-F Garnier. Virtual devices allow you to print and save files to your modern-day computer.

[TASP]

I have located my Thinkjet. It's still in the backyard storage shed. The battery pack is in the same box and boy is it a corroded mess !! Glad it wasn't in the printer.

That box has the 9114 disc drive in it too, and the battery pack for it is just as scary. I'll rebuild one pack for both. I have maybe 75 to 100 floppy discs, I'm curious what's on them, my scribblings don't mean much to me.

As for the Thinkjet, I found at least one ink cartridge new in the packaging, I wonder f it is still good?

I also have a huge sheaf of printer paper. If the Thinkjet works I'll probably print some barcode with it, I'm sure I have the programs for that somewhere, probably in the PPCJournals, on card reader cards, and on a cassette, and a floppy. One of the few things I remember doing besides printing calendars, banners and work related stuff, was printing barcode on the Thinkjet.

I remember having the Radio Shack mini plotter too (printed with a turret with 4 colors of ink in little pens) but I definitely remember it getting broken and I pitched it. It was a fun little gizmo, miss it. I think it ran off my HP-IL with the 82166 converter I have.

[Dave Frederickson]

(03-04-2015 03:04 AM)TASP Wrote:  I have located my Thinkjet. It's still in the backyard storage shed. The battery pack is in the same box and boy is it a corroded mess !! Glad it wasn't in the printer.

That box has the 9114 disc drive in it too, and the battery pack for it is just as scary. I'll rebuild one pack for both.

Unfortunately you'll need to refurbish both batteries because they're different. The 9114 takes a block-type lead acid battery while your printer uses Sub C NiCd's. The 9114 battery is easy to replace and only costs $10. I should mention that an AC adapter can easily be made to replace the 9114 battery. Your ink cartridge has long expired. 51604A cartridges are available everywhere.

[TASP]

ah ha !

I have 2 battery packs for my Thinkjet and now I know what that big white thing is in the other box of stuff,


thanx !!

[Garth Wilson]

I hope this is ok since the topic has migrated.

My Thinkjet no longer prints. It acts like the cartridge is dead, but all cartridges act the same. Absolutely no printing at all, even right after priming the cartridge and cleaning the contacts. The printer goes through the motions, but the paper stays totally white. Are there any easy things to look for? It's not much of an issue, because I go through other interfaces to print with parallel dot-matrix impact printers.

As for the battery in the Thinkjet, mine went bad in the late 1980's. When I found out how much a new one cost, I first replaced it with a 9V battery. That worked as long as the battery was brand new; but after about six pages, the battery could no longer deliver enough peak current for the job. I probably could have just put it in the battery box along with a big capacitor and gotten away with it. What I did instead was to make a 7.8V regulated power supply, which cost me fifty cents. I had everything I needed to make it except one zener diode, and the diode was fifty cents.

I never bought the disc drive, but my tape drive still works like new, as do my tapes, using an external regulated power supply since its batteries are long dead too; but I have a lot of memory in my 71 and 41 so I seldom need to get the drive out.

Someone gave me a beat-up but working 75, but I have never used it. It has no battery pack, so I clipped an external regulated power supply onto the terminals to chek it out.

[Paul Berger (Canada)]

(03-04-2015 06:35 AM)Garth Wilson Wrote:  My Thinkjet no longer prints. It acts like the cartridge is dead, but all cartridges act the same. Absolutely no printing at all, even right after priming the cartridge and cleaning the contacts. The printer goes through the motions, but the paper stays totally white. Are there any easy things to look for? It's not much of an issue, because I go through other interfaces to print with parallel dot-matrix impact printers.

Have you ever had ink leak out onto the head carriage? The ink is slightly corrosive and if left on the contact area it will corrode away the connections. The contacts will look fine as the plating seems to protect them but there is a little of the bare copper foil on the flexible circuit that connects to the ink cartridge. The symptom is usually dropped dots but there is also a common connection that would cause no printing if broken.

[TASP]

If the platen advances and the cartridge goes side to side, and there is no ink deposited no matter what cartridge is installed implies an electrical problem such as Garth noted.

If the contacts are OK, then it is further upstream; cabling, or driver electronics.

[Dave Frederickson]

(03-04-2015 03:15 PM)TASP Wrote:  If the platen advances and the cartridge goes side to side, and there is no ink deposited no matter what cartridge is installed implies an electrical problem such as Garth noted.

If the contacts are OK, then it is further upstream; cabling, or driver electronics.

Leaking ink and over-cleaning destroyed the contacts on the flex cable on my 2225B. Luckily I found a cheap printer on eBay with a good cable.

Adam and Paul shared their experiences in this post.

If it's not the cable, then yes, it's the electronics, but it's probably the cable.

You might like to check out the Service Manual.

Dave

[TASP]

Wonder what condition mine is in?

I figured the battery being out of it would imply it is probably going to work, but, without looking, I'd almost bet there is an ink cartridge in it.

Sounds like 25 years ago I should have taken it out and swabbed the contact area with rubbing alcohol.

Poo.

My storage shed is not heated, but it has been dry inside. The winter cold is unabated, but in summer it was never that hot inside.

[Garth Wilson]

Thanks. It sounds like it's probably the ribbon cable then. Ink has never leaked in the head carriage, and I only put clean cartridges in, and the printing stopped working suddenly, ie, it did not degrade over time. I had many cartridges of black and different colors plus the ones that worked better on plain paper (so you don't always have to use the inkjet-specific type), and they all quit working at once.

[TASP]

Ewww.

Went and looked closer at my Thinkjet.

Ink cartridge is still in it, and there is ink sludge all over.

And I've read here the cassette drive is functionally defunct these days too. Hope I can get the 9114 up and running without too much bother.

I presume if I want to clean my Thinkjet Q-Tips and rubbing alcohol will do ?


Or do I need to extract a special solvent from rare and expensive Tibetan goose berries ??

[Dave Frederickson]

(03-04-2015 09:05 PM)TASP Wrote:  Ewww.

Went and looked closer at my Thinkjet.

Ink cartridge is still in it, and there is ink sludge all over.

And I've read here the cassette drive is functionally defunct these days too. Hope I can get the 9114 up and running without too much bother.

I presume if I want to clean my Thinkjet Q-Tips and rubbing alcohol will do ?


Or do I need to extract a special solvent from rare and expensive Tibetan goose berries ??

That's exactly what happened to my printer. I had to completely disassemble it to get it clean. I made the mistake of using a too high concentration alcohol plus an aerosol degreaser and it caused the flex to delaminate. Start with 70% and be gentle.

9114: Most problems are due to the grease in the eject mechanism hardening. This can cause the disc to mangle the R/W head. I suggest you disassemble the drive and clean and lube it before putting in a disc. Here's a list of repair parts.

Dave