Choosing an HP-48



#25

Hello all,

I am looking for a not-collectible, not pristine HP-48, as a "discovery machine" for this generation of calculators. [Is RPL that evil? :-)].

I looked on this site for a comparison table between S(x) and G(x) series, but as you know, the 48S are the last covered. (Nice tool anyway, thanks David)

The Gs are naturally more expensive, and I wonder if you could share your experiences with either/both series.

In no particular order, here are some basic interrogations

- is one series sturdier than the other? (they seem difficult to open/refurbish/repair)

- are 32k RAM useable, or should I target a 128k machine (SX+extRAM or G+ or GX), or should I expect to need even more?

- are -X versions that useful, since cards seem extinct?

- are the S- "fast enough", given the "typical" problem you throw at them?

I realize that for most of these, the short answer is "it depends"... I would appreciate personnal experience / typical cases reports, as I can't really relate the technical specifications to any real world experience.

Thanks for your help!

Etienne
(Still waiting for bits & pieces to set up my WP34S "flashing station")


#26

Hi Etienne,
I'm going to try to answer your question - all is strictly "in my humble opinion" of course! :)

Quote:
I am looking for a not-collectible, not pristine HP-48, as a "discovery machine" for this generation of calculators. [Is RPL that evil? :-)].
I think they're great machines. I have never shared the "negative feelings" about the 48 series' complexity or unfriendliness, and I've always loved RPL - to the point that I just "put up" with RPN because I can't get RPL on a smaller machine! ;)

Quote:
The Gs are naturally more expensive, and I wonder if you could share your experiences with either/both series.
If you find a well-used one (see my recent post) the price difference isn't much. It all depends on the condition and on the seller's choices, but a good GX can be had for less than many sellers ask for a S/SX.

Quote:
- is one series sturdier than the other? (they seem difficult to open/refurbish/repair)

They *are* very difficult to open. It can be done, and I've done it several times, but especially the first time it's difficult to end up with a machine that looks (and especially feels) like new. And it's time consuming.
Apart from that, as far as I can tell the build quality is exactly the same (though the later Gs, made in Indonesia, have painted keys instead of molded).
Quote:
- are 32k RAM useable, or should I target a 128k machine (SX+extRAM or G+ or GX), or should I expect to need even more?

32KB are not much. I started out with a G, and I found myself constantly moving things between the computer and the calculator. And most downloadable libraries (i.e. the wonderful speedui) simply *need* 128KB. So I'd say go for a GX, even though you'll probably never use the cards.
If you buy a G, it's rather easy to replace its memory chip with a 128KB chip, turning it into a GX without the expansion ports, but again, you'd have to open it and you have to be good with a soldering iron.

Quote:
- are the S- "fast enough", given the "typical" problem you throw at them?
I honestly find the S series too slow. Not just in programs or complex calculations: all the UI is much much slower and unresponsive. And the G/GX also have added features and commands. I'd say, if you're not going to collect but use it, go for the G series.

So all in all, I'd just find a good, non-pristine GX or an expanded G if you can find it.
Hope that helps,
Cristian


#27

With the right tools and technique I don't think these are hard to open.

I've repaired about 20 bad keyboard contact S, SX, G & GX's over the years. For sure the first one or two were butchered but after that I can barely tell they were opened.


#28

I know, I too have done that, but the point is exactly that the first couple don't look that good after the procedure. And I don't think the OP wants to sacrifice a few 48's, he just wants to buy one and he would like to know which one... :)

Cristian


#29

Hi,

I happen to have repaired an HP-48G, which has intermittent key problem, yesterday.

It took half an hour to open the case, and another half an hour to fix the contacts and to replace a RAM and an electrolytic capacitor.

Though I have a 50g which have much RAM, I rather prefer 48G's look and feel.

However, 32KB of RAM of the 48G is too small to install some libraries, so I replaced the RAM with a 128KB chip.

Lyuka


Edited: 29 Sept 2011, 2:57 p.m.

#30

Quote:
If you buy a G, it's rather easy to replace its memory chip with a 128KB chip, turning it into a GX without the expansion ports, but again, you'd have to open it and you have to be good with a soldering iron.

Have you considered the "HP48G+" it has 128K ram but no card slots. I have found that to be a good mix. For some extra money you could get a 48GX and 128KB ram card and Merge Page 0 with main memory. That works nicely too once you have all the libraries configured the way you want.

#31

Of the units I own, I find that the SX feels sturdier than the G or GX. Either way, it's almost impossible to open one without causing significant cosmetic damage (and possibly functional damage as well).

You can get by with 32 KB, but it's awfully tight if you plan to do any substantial programming, and you can forget about installing any large libraries. Even adding just a 32 KB card to an SX is a huge improvement. A GX with an extra 128 KB card is more than enough if you don't plan to run the heavy-weights like Alg, Erable, Metakernel, etc.

For the SX, the only difference over the S is the addition of the card slots. If you never want to track down cards, then it won't make a difference. For the GX, you get card slots plus 128 KB internal RAM vs 32 KB in the G, but the GX is just a hair slower than the G because it has to do more bank-switching to accommodate the extra RAM. You can still find secondhand RAM cards, but they rarely come cheap.

If you're doing just typical calculation, the S/SX is fine in terms of speed. It's visibly sluggish, mostly in the areas of display updating, but it makes excellent use of a keyboard buffer, so you don't need to be concerned with typing "too fast" for the machine. You can type ahead, and it will wait to update the display until it's finished working. I keep one on my desk for day-to-day use, and have no issues with it. Honestly, the G and GX are still fairly pokey as well.

Also worth mentioning is that there is a library for the S/SX called simply "GX" which adds a lot of the new functions from the GX (mostly list-based stuff). It's just under 2.5 KB.


#32

Oh, one important thing I forgot to mention about the G/GX, if you choose to get one:

NEVER, EVER TURN OFF LAST ARG.

Whoever designed the keyboard layout was apparently hopped up on cold medicines on the day that they decided where to put PURGE. It was moved to a key adjacent to EDIT, and both are left-shifted functions. It's very, very easy to accidentally delete a program/whatever that you intended to edit. Fortunately, if LAST ARG is enabled, you can immediately press ARG, STO to undelete.

On an S/SX, this isn't an issue, since VISIT is right-shifted, and PURGE is left-shifted, plus they are two keys away.


#33

If I wanted to turn off LASTARG, how would I do that?

How could I check whether LASTARG was turned on or not?

And, for someone using a 48G for exploration (as the OP intends), where is all that information accessible?

Thanks.


#34

It should be on by default, I think. If LAST ARG is enabled, flag -55 will be cleared. You can also press right-shift MODES, FLAG and scroll to 55. Make sure there's no check mark next to it. There are a bunch of other options in there you can change, too.

#35

I have a real HP-48SX at my desk, where it stays. I find it plenty fast enough for what I use it, but I agree, for plotting and solving, it's reeeaaaally slow.

I have installed Emu48, which allows you to load either SX or GX - I have in the past used the Emu48GX for its TVM solver - which is nearly instant even when running in slow mode.

I would suggest you install Emu48 and compare the two, from a speed and functionality point of view, to decided it you want to spend the extra on the GX.

#36

Quote:
The Gs are naturally more expensive, and I wonder if you could share your experiences with either/both series.

Yesterday, on craigslist, I saw a 48G in Santa Fe, NM, for $30! Posting was Sept 9.

Also, a few of my own observations (I own an SX and (2) Gs):

- The display on the G is lightyears better than the SX.

- The G is a bit faster than the GX.

- I cannot tell a difference in build quality between any of the above.

- The SX is very slow. Don't waste your time, literally.

- I bought both of my Gs for under $35 each.

HTH

Edited: 29 Sept 2011, 12:55 p.m. after one or more responses were posted


#37

I would agree that the GX display contrast is generally better than the SX, but the SX has one advantage. Something about the design of the GX LCD causes the darkened pixels to cast shadows on the screen itself. You don't see this when viewing straight-on, but if you're at a shallow angle (such as with the calculator resting on a desk), you'll see a double-image that makes it very difficult to read. The SX has a definite advantage in readability in this regard.

You also don't see this shadowing effect on the 28C and 28S, but those two are excruciatingly slow, and in the case of the 28C, laughably ill-equipped with memory.

#38

Quote:
- The display on the G is lightyears better than the SX.


That's true only if you have one of the last 48G-series models ever made...the black display versions. Most 48G-series and all 48S-series have the poorest quality LCDs that anyone ever put on a calculator.

I have one HP 48SX and two HP 48GX units, all with various HP memory expansion cards installed, all purchased by me at retail cost and used for years. I was very happy to dump these dogs to basement storage when I got the HP 49G+, followed by the HP 50G. The only positive attribute of the 48S/G-series is the keyboard...and that's certainly not enough to make them worthwhile unless one can get them very very cheap, and can tolerate the many faults and limitations which were corrected with the HP 50G.

#39

Check the saginaw Michigan craigslist site for an SX for $10.

#40

I'll add my own US$0.02:

-- 32k is really tight. I highly recommend getting more memory than this, just for the sake of trying out programs that require more memory.

-- Of all the 48-series models, my preference is the 48SX. In part these are for superficial reasons, e.g., I prefer the color scheme and the domestic build quality. Add me to the list: I believe the S-series feels more solid (although not in a way that is easy to qualify) than any of the G-series units I've owned.

-- Yes, the S-series is slow, although I this is mostly an issue with display-intensive operations (equation editor, matrix writer, plotting). For regular calculations and short programs, I'm content with the SX's speed (these are 20-year-old calculating devices, after all).

-- IMHO, the displays between the S-series and the G-series aren't that different, except the later G-series units that have the black LCD, which are very nice. (The units with these displays, alas, are in the minority.)

-- One difference that I haven't seen mentioned yet: battery life. The 3xAAA cells in an S-series calculator will last several times longer than those in a G-series calculator.


#41

FWIW, I find megarat's summary to be the closest to my own experience and preferences. I have never quite understood the complaints about the 48SX display. It's very readable to me. I have compared it to a black screen GX, and find I prefer the SX screen.


#42

This makes me wonder if maybe all my 48s/sx's are duds... All of them have a display that is much much worse than any of my G/GX's. By worse, I mean that the contrast is much more marginal: the difference between an on-pixel and an off-pixel is small. If I increase the contrast, the numbers are nice and dark but the background is darkish too; if I lower the contrast to get a "invisible" background, then also the numbers look very "washed out".
I may try taking some pictures tomorrow if someone is interested.

Cristian


#43

I agree my late production 48S (1992 vintage has a Yorke processor rather than the Clark) does not have the same display as any of my 48G and GX models. If I compare the displays with power off the 48S display is a darker shade of blue green than any of the Gs, and I too find the Gs display to be much improved, even though they are still the blue text screens. It seems both are made by Epson and are model LD-F8845A the 48S one has -22 on the end and the 48G one has -23. Maybe the difference is just a filter on the front that make it look different. I am tempted to swap the LCD from a dead G into the S while I have it apart and see what happens.

#44

Go for as much memory as you can. 32K can be filled quickly if you do a lot of programming. Get a 48GX or 48SX.

The 48G series is faster and performs better despite the 48S having the better colors (IHMO - I am fan of the blue/orange with the a brown background).

RPL is not evil - just slightly different from RPN. For instance, the stack is infinite, so the roll commands are modified a bit. Also, ENTER only terminates number (or object) entry, there is no automatic duplication.

My first HP calculator was an HP48GX - got it in 2001.

Edited: 29 Sept 2011, 11:37 p.m.

#45

All those people who are not sure about the LCD contrast differences between the different HP-48 types,

please read the following archived thread, and take a look at the pics.

HP-48 LCD contrast comparison

The SX and older GX displays have very low contrast, but the GX displays have more contrast than those of the SX.

The late production GX displays have _much_ more contrast than both predecessors, period.

However Han showed that even the SX can be equipped with the high contrast LCD.

Just sacrifice one of those worthless 39g/40g units...


And about performance: A GX loaded with SpeedUI will make the unit much nicer to use,
since nearly all user interface elements react much faster than the original ones.

Sorry, couldn't resist;-) But hey, SpeedUI is free of charge, so just try it.


Edited: 30 Sept 2011, 4:04 a.m.


#46

Quote:
All those people who are not sure about the LCD contrast differences between the different HP-48 types,

please read the following archived thread, and take a look at the pics.

HP-48 LCD contrast comparison

The SX and older GX displays have very low contrast, but the GX displays have more contrast than those of the SX.

The late production GX displays have _much_ more contrast than both predecessors, period.


I don't know, my 48SX's look more like the 48G in that photo, but contrastier in real life.
#47

If you want to play around a little bit with RPL on a real piece of hardware an HP 48G will fit most situations.



However, as soon as you want to start with all those fine libraries stated above in this thread you have no chance with the memory shortcomings of a 32 kB HP 48G - you will have to upgrade to a 128 kB GX. But even then, some applications (e.g. SpeedUI) come with a bundle of libraries that will reduce the memory considerably.

Then you have to search for a 128 kB card which is in fact rare and may cost more than the HP 48GX itself. And if you want to expand the calc beyond the 256 kB threshold, you have to get expansion cards which are almost impossible to get. (Or you will have to be a master of the soldering iron and a PCB virtuoso to compose your own cards.)



What I highly recommend is the use of EMU48 (already mentioned somewhere above). This great emulator comes with different skins (KML Scripts, of which I like most Jemac's GX because of its quite realistic display of the HP 48G) and can be "upgraded" to any memory configuration that is possible for the original hardware. You can fill it with any available library and save different configurations, just as you like.

Over the serial port you can connect EMU48 to a flesh-and-blood HP 48 and transfer programs you developed in the emulator (given that you purchaded the calculator together with a transfer cable). The great advantage of the emulator is that you can save its current state and restore it easily in case of crashes. A crash in a real calculator is really annoying as it may take seemingly endless time to get it back to the previous condition because you have to load all back with 9600 bauds on the serial line (given that you made an backup beforehand).



But before getting too enthusiastic about EMU48 I will come back to my initial statement: for a little RPL, an HP 48G is perfect. The programs you may develop initially won't put the memory reserves in danger.

At TAS they are usually sold in a decent condition at moderate prices.

#48

Are you interested in a 48gii (4 batteries model) by any chance?


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