Post Reply 
HHP-32k 41C ROM Emulator - Dip switches?
12-06-2017, 05:28 AM
Post: #1
HHP-32k 41C ROM Emulator - Dip switches?
Hi, I found an external HHP-32k 41C ROM emulator and I'm wondering if someone here knows what the various dip switches do. I have the user manual for the HHP-16k 41C Rom Emulator (which is also on TOS), but I'd love to figure out how/if this one works.
   
   

If anyone knows, would be great to hear from you!

Cheers,

PeterP
Find all posts by this user
Quote this message in a reply
12-06-2017, 02:29 PM
Post: #2
RE: HHP-32k 41C ROM Emulator - Dip switches?
(12-06-2017 05:28 AM)PeterP Wrote:  If anyone knows, would be great to hear from you!

The Document set from another well-known HP-41 Enthusiast site includes a QRG & Manual for the HHP-16 emulator; they're probably the same or close enough to figure it out. If you don't have that doc set, holler, I can send the files, they're not too large for email.

--Bob Prosperi
Find all posts by this user
Quote this message in a reply
12-06-2017, 03:47 PM
Post: #3
RE: HHP-32k 41C ROM Emulator - Dip switches?
(12-06-2017 02:29 PM)rprosperi Wrote:  
(12-06-2017 05:28 AM)PeterP Wrote:  If anyone knows, would be great to hear from you!

The Document set from another well-known HP-41 Enthusiast site includes a QRG & Manual for the HHP-16 emulator; they're probably the same or close enough to figure it out. If you don't have that doc set, holler, I can send the files, they're not too large for email.

Yep, I’ve looked at that one, and it describes 2 of the three sets of dip switches (the ones towards the back of the unit. But I couldn’t quite figure out what the third set is for, the one closest to the cable. And the usage of the others is pretty intricate for a simple guy like me (what mixtures of EPROMs are plugged in) so I would not have been able to figure it out.

And the only configuration I get to work right now shows up with the printer rom...

Cheers,

PeterP
Find all posts by this user
Quote this message in a reply
12-06-2017, 04:55 PM
Post: #4
RE: HHP-32k 41C ROM Emulator - Dip switches?
(12-06-2017 03:47 PM)PeterP Wrote:  Yep, I’ve looked at that one, and it describes 2 of the three sets of dip switches (the ones towards the back of the unit. But I couldn’t quite figure out what the third set is for, the one closest to the cable. And the usage of the others is pretty intricate for a simple guy like me (what mixtures of EPROMs are plugged in) so I would not have been able to figure it out.

Stumped! I looked through the Educalc catalog database on Jake's latest DVD and there are lots of products, but I don't see these in there; was hoping the product description might shed some light.

Will have to wait for someone with one of these to notice and comment.

--Bob Prosperi
Find all posts by this user
Quote this message in a reply
12-06-2017, 05:37 PM (This post was last modified: 12-06-2017 05:43 PM by Sylvain Cote.)
Post: #5
RE: HHP-32k 41C ROM Emulator - Dip switches?
I have a HHP-16K unit and a HHP-PE-16K unit with the manuals but not the 32K version.
HHP also produced a 32KB unit of their card reader eprom box (HHP-PE-32K).
Matthias seems to have one in his collection.
He may have the manual and it could conceivable that the dip switches operates the same way.
Just a thought.
I will check tonight if the dip switches of my two units operates the same way.
Sylvain
Edit: have a look on this thread
Find all posts by this user
Quote this message in a reply
12-06-2017, 06:56 PM
Post: #6
RE: HHP-32k 41C ROM Emulator - Dip switches?
(12-06-2017 05:37 PM)Sylvain Cote Wrote:  I have a HHP-16K unit and a HHP-PE-16K unit with the manuals but not the 32K version.
HHP also produced a 32KB unit of their card reader eprom box (HHP-PE-32K).
Matthias seems to have one in his collection.
He may have the manual and it could conceivable that the dip switches operates the same way.
Just a thought.
I will check tonight if the dip switches of my two units operates the same way.
Sylvain
Edit: have a look on this thread

The card reader one has only 2 EPROM chips and 2 sets of dip switches, while this one has three EPROM chips and 3 sets of dip switches, which is what is stumping me.

Cheers,

PeterP
Find all posts by this user
Quote this message in a reply
12-06-2017, 07:35 PM (This post was last modified: 12-06-2017 07:40 PM by Dave Frederickson.)
Post: #7
RE: HHP-32k 41C ROM Emulator - Dip switches?
It looks like a second PCB was piggybacked onto the 16k version of the board to make the 32k version.

The top set of switches are still the configuration DIP switches.

The middle set of switches would be the address switches for one of the EPROM's, probably the one with the socket labeled B1.

The left set of switches would then be the address switches for the other EPROM, the one labeled B2.

or

One set of address switches is for the top half of B1 and B2 and the other for the bottom half. This looks more consistent with the 16k manual on TOS.

Dave
Find all posts by this user
Quote this message in a reply
12-06-2017, 10:35 PM
Post: #8
RE: HHP-32k 41C ROM Emulator - Dip switches?
Interesting subject. Thanks for sharing.
So I spent a couple of hours reading the available information on these HHP ROM emulator modules and comparing with the official HP 41C information.

In order to talk to the 41C, the I/O protocol must be followed as specified in the 41C Service Guide.
And one needs to understand how the HHP-16K is mapping its external EPROM memory space into the 41C ROM address space.

The 41C ROM address space consists of 64K addresses segmented in 16 blocks of 4K addresses each. These ROM address blocks are identified from 0 to 15.

For simplicity, let us say that ROM address blocks 0 to 7 are reserved for system and peripherals.

This leaves address blocks 8 to 15 with a maximum total of 32K addresses available to be mapped by the HHP-16K module.

Each 41C ROM address uses a 10-bit data word length.

This means that the HHP-16K must use more than one single 27xx EPROM 8-bit data word to present a 10-bit data word to the 41C.

And indeed the HHP-16K Setup Instructions from TOS site are very precise despite hiding some details concerning how the 10-bit data word is split between two EPROMs.
This information is found here , here and here.


EPROM ZIF sockets:

- The two bigger 28-pin DIP ZIF sockets marked as L8-2 and L8-1, hold the ROM data bits 0 to 7.
One or two EPROMs can be used here depending on the required size.
If two EPROMs are used they will be addressed sequentially.

- The smaller 24-pin DIP ZIF socket marked as U2 hold the ROM data bits 8 and 9.
Here the EPROMs will have smaller size than on the two L8 sockets (24-pin versus 28-pin EPROMs).
This apparently do not make sense because the ROM address space should be the same for the L8 and U2 ROMs assuming they are in parallel to build the 10-bit data words.
But the explanation is found elsewhere in the HHP manual and on the links above:
Each 4 groups of 2-bit are packed into a single 8-bit data word per ROM address.
The HP SDS-IT custom ROM development system could be used to pack.
It seems these packing program tools are called EPROM.EXE and HIGHLOW.EXE.


DIP Switches:

HHP-16K uses two DIP 4-switches, one to set the starting block address for the installed EPROM size, and the another to set the EPROM total size and configuration.

- The DIP 4-switches closer to the ZIP socket U2 (the smaller of the three) sets EPROM total size and configuration.
The same size can be achieved by a single EPROM or a combination of two EPROMS in the L8 ZIF sockets.

- The DIP 4-switches located between two DIP 14-pin CMOS IC's set the starting block address to map the EPROMs.


Now, HHP-16K states that in order to obtain a 16K address space, a 2732 EPROM must be used in the ZIF socket U2, and two 2764 EPROMs in ZIF sockets L8.

Let us see, two 2764 gives us a total of 16K address of 8-bit data words each.
The 2732 gives us 4 K addresses with 8-bit data words each.
So a total of 4k * 8 = 32Kbit, which divided by two (to hold bits 8 and 9) gives us exactly 16K "addresses" with 2-bit data words each.
This seems right to me.


Concerning the HHP-32K:

What do we see in the HHP-32K published picture in post 1?
A 2732 EPROM in the ZIF socket U2.
So this HHP-32K is installed with an unknown application that takes no more than 16K addresses, meaning that it could be installed on a HHP-16K.

I agree with Dave that the daughterboard (piggyback mounted) labeled "HHP-12KBS Bank Mod." contains additional logic to support a double address ROM space, up to the 32K maximum addresses supported by the 41C.

My guess is that in order to install an application with 32K addresses, we would need to use:
- One 2764 EPROM on the U2 position;
- Two 27128 EPROMs on the L8 positions (or one 27256 in one of the L8 positions, if supported).


As for the DIP switches, that's the big unknown.

- The DIP switch located between two DIP 14-pin CMOS IC's that sets the starting block address to map the EPROMs could use the same table as used for the HHP-16K.

- The additional third DIP switch probably complements the original DIP switch (close to the U2 ZIF socket) to set additional EPROM configuration sizes without the need to remap the hardware configuration in the motherboard.

With a bit of luck, the solution could be found with some basic reverse engineering, by dismantling the unit to have access to both PCB's (front and back sides) and write down the schematic diagram for analysis.

Jose Mesquita
RadioMuseum.org member

Find all posts by this user
Quote this message in a reply
12-07-2017, 12:54 AM
Post: #9
RE: HHP-32k 41C ROM Emulator - Dip switches?
Peter,

Still searching for HHP-32K information while playing with my HHC-16K using multiple EPROM & dip switch setup to really understand the behaviour of this thing. Wink
You could try to call or email Mike WEAVER (F. M. WEAVER ASSOCIATES, INC.), the co-creator of this unit to see if he still have information on it.

Sylvain
Find all posts by this user
Quote this message in a reply
12-07-2017, 05:45 AM
Post: #10
RE: HHP-32k 41C ROM Emulator - Dip switches?
(12-07-2017 12:54 AM)Sylvain Cote Wrote:  Peter,

Still searching for HHP-32K information while playing with my HHC-16K using multiple EPROM & dip switch setup to really understand the behaviour of this thing. Wink
You could try to call or email Mike WEAVER (F. M. WEAVER ASSOCIATES, INC.), the co-creator of this unit to see if he still have information on it.

Sylvain

That is an excellent idea!

Cheers,

PeterP
Find all posts by this user
Quote this message in a reply
12-07-2017, 05:46 AM
Post: #11
RE: HHP-32k 41C ROM Emulator - Dip switches?
(12-06-2017 10:35 PM)jebem Wrote:  Interesting subject. Thanks for sharing.
So I spent a couple of hours reading the available information on these HHP ROM emulator modules and comparing with the official HP 41C information.

In order to talk to the 41C, the I/O protocol must be followed as specified in the 41C Service Guide.
And one needs to understand how the HHP-16K is mapping its external EPROM memory space into the 41C ROM address space.

The 41C ROM address space consists of 64K addresses segmented in 16 blocks of 4K addresses each. These ROM address blocks are identified from 0 to 15.

For simplicity, let us say that ROM address blocks 0 to 7 are reserved for system and peripherals.

This leaves address blocks 8 to 15 with a maximum total of 32K addresses available to be mapped by the HHP-16K module.

Each 41C ROM address uses a 10-bit data word length.

This means that the HHP-16K must use more than one single 27xx EPROM 8-bit data word to present a 10-bit data word to the 41C.

And indeed the HHP-16K Setup Instructions from TOS site are very precise despite hiding some details concerning how the 10-bit data word is split between two EPROMs.
This information is found here , here and here.


EPROM ZIF sockets:

- The two bigger 28-pin DIP ZIF sockets marked as L8-2 and L8-1, hold the ROM data bits 0 to 7.
One or two EPROMs can be used here depending on the required size.
If two EPROMs are used they will be addressed sequentially.

- The smaller 24-pin DIP ZIF socket marked as U2 hold the ROM data bits 8 and 9.
Here the EPROMs will have smaller size than on the two L8 sockets (24-pin versus 28-pin EPROMs).
This apparently do not make sense because the ROM address space should be the same for the L8 and U2 ROMs assuming they are in parallel to build the 10-bit data words.
But the explanation is found elsewhere in the HHP manual and on the links above:
Each 4 groups of 2-bit are packed into a single 8-bit data word per ROM address.
The HP SDS-IT custom ROM development system could be used to pack.
It seems these packing program tools are called EPROM.EXE and HIGHLOW.EXE.


DIP Switches:

HHP-16K uses two DIP 4-switches, one to set the starting block address for the installed EPROM size, and the another to set the EPROM total size and configuration.

- The DIP 4-switches closer to the ZIP socket U2 (the smaller of the three) sets EPROM total size and configuration.
The same size can be achieved by a single EPROM or a combination of two EPROMS in the L8 ZIF sockets.

- The DIP 4-switches located between two DIP 14-pin CMOS IC's set the starting block address to map the EPROMs.


Now, HHP-16K states that in order to obtain a 16K address space, a 2732 EPROM must be used in the ZIF socket U2, and two 2764 EPROMs in ZIF sockets L8.

Let us see, two 2764 gives us a total of 16K address of 8-bit data words each.
The 2732 gives us 4 K addresses with 8-bit data words each.
So a total of 4k * 8 = 32Kbit, which divided by two (to hold bits 8 and 9) gives us exactly 16K "addresses" with 2-bit data words each.
This seems right to me.


Concerning the HHP-32K:

What do we see in the HHP-32K published picture in post 1?
A 2732 EPROM in the ZIF socket U2.
So this HHP-32K is installed with an unknown application that takes no more than 16K addresses, meaning that it could be installed on a HHP-16K.

I agree with Dave that the daughterboard (piggyback mounted) labeled "HHP-12KBS Bank Mod." contains additional logic to support a double address ROM space, up to the 32K maximum addresses supported by the 41C.

My guess is that in order to install an application with 32K addresses, we would need to use:
- One 2764 EPROM on the U2 position;
- Two 27128 EPROMs on the L8 positions (or one 27256 in one of the L8 positions, if supported).


As for the DIP switches, that's the big unknown.

- The DIP switch located between two DIP 14-pin CMOS IC's that sets the starting block address to map the EPROMs could use the same table as used for the HHP-16K.

- The additional third DIP switch probably complements the original DIP switch (close to the U2 ZIF socket) to set additional EPROM configuration sizes without the need to remap the hardware configuration in the motherboard.

With a bit of luck, the solution could be found with some basic reverse engineering, by dismantling the unit to have access to both PCB's (front and back sides) and write down the schematic diagram for analysis.

Wow, that's quite detailed and lots of ideas! Let me see if I can figure something out (or dismantle and post pictures) Thank you!!

Cheers,

PeterP
Find all posts by this user
Quote this message in a reply
12-14-2017, 03:54 AM (This post was last modified: 12-14-2017 03:55 AM by PeterP.)
Post: #12
RE: HHP-32k 41C ROM Emulator - Dip switches?
With help from Sylvain I ended up getting in contact with Jacob de Arras (yes, the JDA), who built this device.

He shared his patent for the design of these devices - it is very impressive to read how he built a device specifically targeted for low power consumption. You can find the patent here

Specifically for the HHP-32k unit he told me that it
Quote:It is very rare. Special small build for HP only
.

He gave me one further hint:
Quote:Those were special builds for HP internal use to test some sort of bank switching scheme to increase memory. I do not believe they will just work with "standard" eprom images.

So maybe the 12k piggy-bag board is actually the HP-41 operating system? Maybe that's why the only thing I can get to work is a page with the printer code?

Maybe this information helps the smart people here to figure out more about the unit, including maybe some tests that I should be running (over the Christmas break most likely...)

In any case, I thought I share what I learned. And now it might be even harder to pass the unit on - if the JDA himself say's its very rare...

Cheers,

PeterP
Find all posts by this user
Quote this message in a reply
12-14-2017, 06:13 AM
Post: #13
RE: HHP-32k 41C ROM Emulator - Dip switches?
You talked to the Jim DeArras! Wow!

As you probably know, an HP-41 port occupy 8K, and early modules are either 4K or 8K. Initially there was a 4K chip and 8K was achieved by using two such chips (increasing the cost of a module).

Later HP introduced the 1LG9 (see chapter 11 of SDS-II manual). This is a a 12K chip that can be configured as 4K, 8K or 12K. So the same chip could be used to single, double and even a larger module (Advantage module). However, to avoid occupying more space than what is designated by a physical port, a bank switch scheme was introduced.

HP also used bank switching for the HP-41CX operating system and for the IR printer module.

Judging from the labels on the EPROMs they probably contain the firmware for the IR printer module (it is named Blinky).

I would guess that the B1 holder is bank 1 (main bank), B2 is the banked image and the smaller EPROM contains the upper bits for both pages. The printer firmware occupies page 6 (0110), so the DIP switch to the left could be the address as it shows that pattern.

This was very interesting, thank you for sharing!

Maybe you could read the contents of the EPROMs and compare with a known IR printer image, to see if that is the case and whether it contains an earlier version of the firmware?

I had a quick look at the patent and it basically seems to describe how early MLDLs like the one described in PPC CJ by Lynn Wilkins worked, by turning on EPROMs when accessed. Was that patent enforced and MLDL makers payed patent money? I based my own home made MLDL on that design, but I used a single 6164 (8K) EPROM for each 4K page and read out bits twice and even powered it up a cycle earlier as it was mentioned that the MLDL design would not work with a speeded up HP-41, and my HP-41 was running at 2x. It worked well and I got good mileage with that device for years.

Håkan
Find all posts by this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: