Rewiring Handheld Products Card Reader RAM



#2

I wonder if it's possible to add memory capacity to a 32K Handheld Products RAM, for instance. The Handheld products 32K RAM/EPROM has space for an EPROM, so it seems likely that one could use the space to add some additional RAM. Now, the EPROM wouldn't likely have a WR signal to it but that should be easy to find.

I also wonder if it's likely that they used the same controller for their 32K RAM as they do for their 128K RAM. If so, it should be able to add another 96K of RAM, one would think, with some creative piggybacking.

Also, there is a jumper that has 2 positions, plus a position with no jumper applied, giving 3 possible settings. Anyone know what this jumper is for? Might it be for different RAM configurations? Or, it might be for different sizes of EPROMs. Just curious about this.

As far as I can tell, there is only RAM, EPROM and the controllers. It appears there might be a seperate controller for the EPROM and one for the RAM. Both are on different boards. There is a RAM board and an EPROM board. So, unless the controller is different for each RAM Module size or between RAM and EPROM, it should be possible.

Anyone know if there is any article on reworking a Handheld Products RAM device?


Edited: 20 May 2006, 10:47 p.m.


#3

Each controller chip handles up to 32KB of RAM. To add more RAM, you need more controller chips.

The EPROM has its own controller. It's the same type as the RAM. If you're not using the EPROM, you could repurpose it for RAM. But you'd have to configure it differently so it knows it's talking to RAM instead of EPROM; otherwise it won't allow writing, which defeats the purpose.

I suspect that the jumper is just to connect the configuration daisy chain properly, depending on how many memory controllers are present.

It's reported that the data sheet on the Saturn bytewide memory controller chip was available at some point, but I don't have a copy of it.


#4

Quote:
The EPROM has its own controller. It's the same type as the RAM. If you're not using the EPROM, you could repurpose it for RAM. But you'd have to configure it differently so it knows it's talking to RAM instead of EPROM; otherwise it won't allow writing, which defeats the purpose.
That's what I figured. Do you know the part number for the 32K memory controller? So, if I'm not using EPROM, I should be able to add 32K, it seems.

But I'm curious. If each 32K requires a controller, that means there would be 4 of these boards inside a 128K RAM??? I haven't looked inside a 128K but that seems like a lot of boards for such a small device. OR, to they use 1 or 2 chips for 32K RAM instead of 4 as in the 32K device.?


Edited: 21 May 2006, 12:47 a.m.

#5

Hi,

I wonder if CMT used a similar controller in their 64k EPROM front port module. No reference can be seen, there is no package:

Who made these controllers? Was is HP, or did HHP and CMT design their own controllers?

BTW, the 64k EPROM die size is quite impressive...

J-F

Edited: 21 May 2006, 4:15 a.m.


#6

Hi Mike

Let´s see if I can do something for you.. I just took some photos of my HHP memories (ok, the 32k version I didn´t photograph as you shurly have one...)



Yours,
Matthias


#7

Thanks for taking these photos. The 96K just looks like three 32K stacked boards. Interesting...

So, I wonder what the part number is for this controller chip. I bet, if I can find the number of the controller chip, I can find actual chips.

Anyone know what the part number is for this memory controller chip?

Edited: 21 May 2006, 11:35 a.m.


#8

Quote:
if I can find the number of the controller chip, I can find actual chips

It's marked on the chip. It's the 1Lxn-nnnn number. I doubt that you're going to find any, but it can't hurt to try.


#9

Quote:
It's marked on the chip. It's the 1Lxn-nnnn number.
It's not marked on mine. It has been scratched off of two that I have checked. It has the HP logo but all the writing has marks through it as if someone took an object and scratched of the part numbers.

And I bet they can be found.

Edited: 22 May 2006, 11:27 a.m.


#10

I don't think it is scratched off on mine. I'll have to find it and open it up again. Can't do it right now since this is finals week.

Quote:
And I bet they can be found.

How much?


#11

Oh I don't know. I found HP-IL controllers and they haven't been made in some time. :-) Get me the part number and let me try. :-)

Edited: 22 May 2006, 5:02 p.m.


#12

No, I meant how much are you willing to bet. :-)

#13

The HP part number is 1LQ4-nnnn, where nnnn is different depending on the package (or bare die). I don't have the details of the suffixes.

#14

I suspect that CMT used the same HP chip, purchased in die form.


#15

So it may mean that the chip can control a 64k block, at least for a ROM block. Maybe a pin selectable option? On the other hand, if such an option did exist, why did HHP never release a 32kRAM/64kEPROM module?

J-F


Edited: 22 May 2006, 4:51 a.m.


#16

I just opened a CMT 128k Module and it consists of 4 32k modules, soldered on a mini-mainboard... It seems, that the prices of the 4x CMT32k module was lower than for 2x the 64k modules. I wouldn´t be surpriced if CMT and HHP used the same controller chip, yes.

Matthias

#17

Yes, for EPROM or ROM it can control 64KB. For RAM it can only control 32KB. This is due to a limitation of the 71B, not of the controller chip.

#18

Hi,

I think to recall that J-F once told me

the jumper was for switching between

8K, 16K, and 32K EPROM .

HTH

Raymond


#19

I think to recall that J-F once told me ...

Did I? I don't remember...

No, I don't know what is the purpose of this jumper.

J-F

#20

Turn the EPROM part of the unit topwards, so that you have this setup:


* ABC
* + +
* + +
* + + * = Pins
* + + + = EPROMS socket
* + + ABC = Jumpers
* + +
* + +
* + +

Jumper Setting:

AB --> 32K
BC --> 8K and 16K

Yours,
Matthias


#21

My posting was not the best, sorry... Yes, the pins are for selecting 8k/16k or 32k. Place the module on your table, so that you can see the pins on the right upper edge. From left to right the Pins are A-B-C... Juppered AB is for 8k/16k EPROMs, jumpered BC is for 32k EPROMs.
Is this readable now?

Matthias


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