W&W 32K RAMBOX re-initialization ROM

[Jurgen Keller]

In 2019 I wrote the HP-41CY re-initialization ROM, see this thread. Now, I took care of the simpler case, namely re-initializing a W&W 32K RAMBOX. Actually, this is trivial because no bank switching is involved. Therefore, you do not really need a dedicated ROM for that, you can also do it manually. So this project is just for convenience.

I've published everything on Github. The README explains how to execute the re-initialization process, hopefully comprehensible enough. If not, let me know and I will try to clarify.

Now, the days where empty backup batteries caused a disaster are gone :-)

[PeterP]

Awesome! I could have used this as I was re-initialiying a number of EPROM boxes after the move.

Now - can you pls do the same for the ERAMCO Ramboxes, for 32k, 64k, and 128k after yet another move and neglect? Just some neat little InitRom that we can just plug in and it does all the work, just like your perfect InitCY rom (which I also gave a massive workout during this exercise and it worked perfectly!)

[Jurgen Keller]

Peter, thanks for your positive feedback! The ERAMCO 64K RAMBOX is already on my list. The 128K RAMBOX is quite a rare beast, not sure if I will ever manage to get one. I also don't have a 32K ERAMCO RAMBOX.

If you want to use your ERAMCO RAMBOX with a W&W O/S I think the RBINI ROM should already do the trick. This is an interesting option because the W&W O/S only takes a single page.

I think only the 128K ERAMCO RAMBOX has software driven bank switching. So this might be the most challenging one.

[Diego Diaz]

Hi Jürgen, Peter,

The access to the ERAMCO RSU-2 128K Rambox is documented in this article from 2008... (Tempus fugit).

Also there is an ERAMCO RSU-2 256K Rambox using 10x62256 RAM chips. I have not seen this documented anywhere, so it may be just a prototype.

I have only seen one such unit, wich I repaired back in 2017. Coincitentally I have received it again for service and OS restore this very morning.

The access to the 8x32K banks in this unit is also SW driven, but works in a very different way from its 128K counterpart.

I haven't yet got my notes about the details, and certainly I can't remember the procedures from the top of my head after 7+ years.

If the owner allows me, I'd gladly share what I found in case there is some interest on the subject.

Best wishes from Spain.

Diego.

PS: @Jürgen, Finally, I managed to recover the 41CY I was working on last week.

[Jurgen Keller]

(06-28-2024 05:38 PM)Diego Diaz Wrote:  The access to the ERAMCO RSU-2 128K Rambox is documented in this article from 2008... (Tempus fugit).

Ah, we are all getting older I guess. Luckily, the community brain still works, thanks for the pointer. Very interesting stuff, I have to look into that in more detail.

(06-28-2024 05:38 PM)Diego Diaz Wrote:  Also there is an ERAMCO RSU-2 256K Rambox using 10x62256 RAM chips. I have not seen this documented anywhere, so it may be just a prototype.

Wow, it will need some efforts to fill all that RAM!

(06-28-2024 05:38 PM)Diego Diaz Wrote:  If the owner allows me, I'd gladly share what I found in case there is some interest on the subject.

That would be great!

(06-28-2024 05:38 PM)Diego Diaz Wrote:  PS: @Jürgen, Finally, I managed to recover the 41CY I was working on last week.

Good to hear it finally worked out. I'd be interested what the problem was. Maybe you can PM me.

[Diego Diaz]

Hi all,

I've found my notes about the 256K ERAMCO RSU-2, and the owner has kindly allowed me to share this info.

Here's an abstract of the procedure to handle the 8x32K banks:

- To select one of the banks just write the bank nr. (in the range 0-7) into any address in the range h'4000 to h'7FFF.(*)

- To enable a page, just write h'10n (n=page number in the range 8-F) into any address in the range h'0000 to h'3FFF.

- To disable a page, write h'00n instead. Note that disabling a page only affect the reading process. Contents can still be written using instruction h'040 if the page address is accessed.

- There is a Read Enable Switch at the top of the unit that affects the whole 256K. Sliding it to the left prevents the HP-41 from reading any RAM contents.

- However, writing is always enabled, so care must be taken in order to avoid accidental overwriting on the active bank, even when the page is "disabled" as noted above.

(*) Since the bank selection address range includes the NoV's control word at h'4100; the user must keep track of the active bank, to restore it in case of conflict if both devices are used simultaneously.

Regrettably the original ERAMCO OS for this unit is not available AFAIK. Supposedly that OS should contain specific functions to handle the procedures described above.

All the best from the Canary Islands.

Diego.