Retrotronik RAM card for HP 48GX

[acoto]

Hello -

Just found this 128KB RAM card in ebay:

https://www.ebay.com/itm/154496920358

QR code redirects to this site
https://retrotronik.com/products/

Quite interesting. Planning to buy one

Seems to be a new implementation, but no details about design.

[rprosperi]

I agree they look both new and interesting. I've ordered one and it should be delivered in a few days (it is now in customs in Miami, on its way to NY). If you are willing to wait, I'd be happy to post some comments after testing it upon receipt.

If all is well, as I expect it will be, I will likely order another one, I have just found another 48SX in a closet with no RAM card.

[Kostas Kritsilas]

(06-20-2021 01:50 AM)rprosperi Wrote:  I agree they look both new and interesting. I've ordered one and it should be delivered in a few days (it is now in customs in Miami, on its way to NY). If you are willing to wait, I'd be happy to post some comments after testing it upon receipt.

If all is well, as I expect it will be, I will likely order another one, I have just found another 48SX in a closet with no RAM card.

I find it odd that they only specify the HP-48GX for the 128K card, either on the eBay listing, or on their own web site. Memory cards up to 256K should work on the HP-48SX, shouldn't they, or in slot 1 of the HP-48GX. Slot 2 is supposed to take up to 2MB cards in slot 2 of the HP-48GX only.

[rprosperi]

128K cards should work in either slot of any 48SX/GX.

Tripod made some special 256K and 512K cards for the 48SX, but they required manual bank selection, done by commands in a small library. These cards cannot be used in a 48GX.

Conversely, the 256k-4096k (4MB) cards intended for the 48GX cannot be used in an SX. These cards also used bank switching techniques, but controlled and hidden by the OS.

So yes, these cards should work anywhere; perhaps the manufacturer considers only GX machines to still be in use and is therefor marketing only to them. It seems lots of surveyors still use 48GX's to this day, but I'm not aware of any that still use a 48SX.

[jonese]

Part of it look 3D printed. Not saying it's bad, just an observation.

[Kostas Kritsilas]

(06-20-2021 01:50 AM)rprosperi Wrote:  I agree they look both new and interesting. I've ordered one and it should be delivered in a few days (it is now in customs in Miami, on its way to NY). If you are willing to wait, I'd be happy to post some comments after testing it upon receipt.

If all is well, as I expect it will be, I will likely order another one, I have just found another 48SX in a closet with no RAM card.

Has it arrived yet, and have you had a chance to try it out? I'm interested in getting one, so I went to the link that was posted earlier, and have not had a response in 2 days. Are they for real, or are they known to be slow in responding?

[rprosperi]

Not yet, it seems to be stuck in customs, all too common since the Pandemic changed just about everything. I did ask a question before my purchase which was answered promptly, but otherwise have not communicated with the seller, so can't say for sure about typical response time. Hopefully seller will reply soon.

[arborist]

I'm using mine (128k) to run Metakernel in slot 1. So far so good. I will report here if I run into issues!

[Sylvain Cote]

I missed that one, anyway he was not shipping to Canada, I just sent him a message through his web site.
Question, how do you control the 128KB bank switching with the 2MB card in a HP-48GX ?

[Eric Rechlin]

(07-01-2021 08:50 PM)Sylvain Cote Wrote:  I missed that one, anyway he was not shipping to Canada, I just sent him a message through his web site.
Question, how do you control the 128KB bank switching with the 2MB card in a HP-48GX ?

No need to worry about that on the GX (though of course it only works in slot 2). It divides cards into one port per 128 KB bank. Although 1 MB was the largest card HP sold for it, 2 MB cards work seamlessly. 4 MB cards mostly function but have a problem with the last port, so they generally aren't recommended.

[rprosperi]

(07-01-2021 10:01 PM)Eric Rechlin Wrote:  

(07-01-2021 08:50 PM)Sylvain Cote Wrote:  I missed that one, anyway he was not shipping to Canada, I just sent him a message through his web site.
Question, how do you control the 128KB bank switching with the 2MB card in a HP-48GX ?

No need to worry about that on the GX (though of course it only works in slot 2). It divides cards into one port per 128 KB bank. Although 1 MB was the largest card HP sold for it, 2 MB cards work seamlessly. 4 MB cards mostly function but have a problem with the last port, so they generally aren't recommended.

To expand on Eric's comments:

When you put a 128KB card in a GX, you have: Port0, Port1, Port2
When you put a 1MB card in a GX, you have: Port0, Port1, Port2, Port3, Port4, Port5, Port6, Port7, Port8, Port9
When you put a 2MB card in a GX, you have: Port0 - Port17
When you put a 4MB card in a GX, you have: Port0 - Port32 (and not 33)

Technically, it is in fact bank switching, but its hidden from the user and 'invisible and seamless'. And since you can only move items between ports via the stack, it remains invisible even when using it.

These extended ports can best be used with a graphical file management tool such as:

PCT: https://www.hpcalc.org/details/2457

or, IMHO even better:

Filer48: https://www.hpcalc.org/details/4242

[Eric Rechlin]

(07-02-2021 02:27 AM)rprosperi Wrote:  When you put a 128KB card in a GX, you have: Port0, Port1, Port2
When you put a 1MB card in a GX, you have: Port0, Port1, Port2, Port3, Port4, Port5, Port6, Port7, Port8, Port9
When you put a 2MB card in a GX, you have: Port0 - Port17
When you put a 4MB card in a GX, you have: Port0 - Port32 (and not 33)

Just a clarification here, the above are only correct when you also have a 128 KB card in slot 1. If you don't, then remove port 1 from the lists.

[rprosperi]

(07-02-2021 02:42 AM)Eric Rechlin Wrote:  

(07-02-2021 02:27 AM)rprosperi Wrote:  When you put a 128KB card in a GX, you have: Port0, Port1, Port2
When you put a 1MB card in a GX, you have: Port0, Port1, Port2, Port3, Port4, Port5, Port6, Port7, Port8, Port9
When you put a 2MB card in a GX, you have: Port0 - Port17
When you put a 4MB card in a GX, you have: Port0 - Port32 (and not 33)

Just a clarification here, the above are only correct when you also have a 128 KB card in slot 1. If you don't, then remove port 1 from the lists.

Dang! Really good point, thanks for clarifying this Eric.

[Joe Horn]

(07-01-2021 10:01 PM)Eric Rechlin Wrote:  4 MB cards mostly function but have a problem with the last port, so they generally aren't recommended.

Does anybody remember (or have a link to) what the Port 33 Bug was, exactly? I vaguely remember that Port 33 will actually exist (if you have a 4 MB card in slot 2 of a 48 GX), but that it misbehaves in some nasty way. Any info in that regard would be helpful. Thanks in advance! Related question: Is there any way of write-protecting ONLY Port 33, so as to avoid getting bitten by the Port 33 Bug?

[rprosperi]

(07-02-2021 06:56 PM)Joe Horn Wrote:  

(07-01-2021 10:01 PM)Eric Rechlin Wrote:  4 MB cards mostly function but have a problem with the last port, so they generally aren't recommended.

Does anybody remember (or have a link to) what the Port 33 Bug was, exactly? I vaguely remember that Port 33 will actually exist (if you have a 4 MB card in slot 2 of a 48 GX), but that it misbehaves in some nasty way. Any info in that regard would be helpful. Thanks in advance! Related question: Is there any way of write-protecting ONLY Port 33, so as to avoid getting bitten by the Port 33 Bug?

Only a vague memory, not unlike yours, that Port-33 does in fact exist, but it is unreliable as data can be corrupted. I also kinda-remember that the 48GX uses one of the address/data lines used when Port-33 is active, for some other purpose, which is why it can clobber data you store there.

Since most port operations are controlled by the user (though I suppose an errant program could do that too) it's generally safe IIRC to simply ignore it. What isn't clear, since Port-33 is definitely there and exists if a 4MB card is installed, is what happens when you use wildcards to access data across any card, e.g. EVAL or PURGE ":&:MYDATA". Again if you don't store anything there, it should be OK... statistically speaking.

The RAM cards implement write-protect at the card level, so almost certainly not. There were programs/libraries that implemented port-locking, but I imagine such locking is only effective within the scope of that program. The FAQ has some fairly detailed notes from Dave Arnet on the various bits and signal lines involved; perhaps something could be done in assembler, but if nothing has emerged yet, it's not likely needed. Besides, all 11 people that own a 4MB RAM card know about the problem...

[Sylvain Cote]

(07-01-2021 08:50 PM)Sylvain Cote Wrote:  I missed that one, anyway he was not shipping to Canada, I just sent him a message through his web site.

I got this response from a representative of retrotronik:

Quote:Thank you for your interest in our products.
We are currently out of stock of 1MB and 2MB cards.
For low quantity (<50 units) orders, 128kB card retail at 40 Euro, 1MB cards retail at 65Euro and 2MB cards retail at 99Euro plus shipping.
We can ship to Canada but this location is outside of our regular shipping plan (Europe and USA only) so it would ship on standard international registered mail without insurance.
Please notice that you will be responsible for any loss or delay and for any customs costs.

I will wait for the 2MB card to become available before ordering some.

Sylvain

[Eric Rechlin]

If you try to use a 4 MB card, the last port won't show up and you will get a perpetual Invalid Card Data error message on powerup. There was a resolution to this with a special switch on some cards to allow you to switch two of the top banks and properly initialize all of them to avoid the error.

I don't recall them ever being available in mass-produced form (only in the homemade-style with bare circuit boards) so I doubt many exist. I think Oliver Klotz was the only person to actually try to sell them in the latter form; apparently they cost 499 DM twenty years ago.

[rprosperi]

I received my Retrotronik HP-48SX/GX 128KB RAM card late this past week; it came protected in a anti static bag, along with a new, sealed battery, together in a well-padded small box. I of course appreciate the lower cost, but also quite like the modern industrial design and though quite light, the cards feel solid and well-made. Unfortunately, the card could not be fully inserted into card slots of any of my 48SX or 48GX machines. I contacted the seller, and he immediately advised me that a few cards indeed had been assembled by mistake with the wrong, slightly too-thick plastic shell, but that others had also been sold with the correct shell and he had received positive feedback from those buyers. He also volunteered that that a buyer in The Netherlands received another card also with the incorrect part. The seller then immediately provided me a full refund, and informed me he had created a revised design and all new cards will include the correct, thinner shell.

I told him I had many HP and other 3rd-party RAM cards and offered to make some measurements and send him the data. More conversation ensued and eventually I suggested loaning him some sample cards and another machine to measure, compare and confirm dimensions and fit of the new design. He has already mailed me a card with the revised shell design to verify in my machines, this should probably arrive around the end of this coming week. Once confirmed, purchasing via the website (https://retrotronik.com/) and I also assume via eBay should quickly become available again.

I also mentioned the MoHPC Forums and that this exact product was being discussed in this thread, and encouraged him to register and join into the discussion here, for direct access to buyers, their feedback and comments, but also to be ready for lots of questions about when the larger cards seen in the website will be coming. He assured me that they are indeed coming, but only after the new design has been confirmed by users.

I buy a lot of 3rd-party items (ok, too many…) on eBay and have had many different kinds of experiences, and I can say I am both surprised and pleased at how forthright, eager and helpful this seller had been. It has been a pleasure to work through this issue, nice to work with a supplier so interested in ensuring the product is correct and the customer satisfied. I will post additional comments when the card with the new shell design arrives, and hopefully this seller will join our discussion here. It’s nice to welcome a new vendor into the community; I expect this small issue will be corrected soon and look forward to positive feedback from other customers.

[Kiwi]

I also ordered one of these cards mid of June and received it quite fast (in less than a week with international shipping). Unfortunately, I also received one of these cards with a small manufacturing mistake with the card shell. Communication was very good with the seller and I had a full refund.

They are now looking into solving this issue to make sure this will not happen again in the future.

On the positive side I'd like to add that even if the 128K RAM card should only be used in a HP48GX (as mentioned by the seller), it perfectly works in a HP48SX. I also appreciated the clever design where the built-in (half) latch is molded into the shell.

[jcrbarbosa]

Hello.

Thank you all for your interest and feedback on Retrotronik products.
Unfortunately, a small batch of 5 cards was sold from which at least 2 cards shells were manufactured using a wrong (older) printing file.
Because of this, sales are suspended until we can make sure this will not happen again and until we have complete and perfect feedback from both buyers and testers.
We’re getting good feedback so far, so I’m confident we will resume sales soon.

I want to thank Bob and Kiwi for their positive attitude, care, and availability.

Once we have any news on the sales, we'll announce it here.
Meanwhile, feel free to ask any questions about the products or to make any suggestions.

João
https://retrotronik.com