HP97 The journey begins

[Massimo Gnerucci]

Well done Tony! I put it on my shopping list.

[teenix]

(04-25-2024 12:11 PM)rprosperi Wrote:  WOW!!

I've been following this thru its gestation, but honestly missed or forgotten some of the features, or some smaller details of features, but this is quite amazing, Tony, very well done!!

A couple questions:

A. Why does the 25C support fewer program files than the 29C? Given the same platform, one would think they could support the same. Unless simply because the 25C was less capable than a 29C and that's how things must be, which I could understand and support.

B. Can the original power adapter be used to charge the LiPo battery and operate the device?

C. Does the new battery fit in an original, or 3D printed equivalent, battery pac?

D. Purpose of new GSB 49 instruction?

E. It appears installation consists of simply opening the unit, replacing the old board with the new one, and reassembling, is that correct?

Looking forward to one of these...

A. Just the size of the memory device. I thought the 200 or so programs for the 25C would suffice, and as you mention the 29C is more capable, so I thought it may get used more often. I could get larger memory, but I was thinking about cost. The 29C can also load Program or load/save Data files while a program is running so the extra program storage may be of more use.

B. No, the original charger outputs AC and would damage the board. Dave (Dreato) from the Forum has made up suitable USB charge cables for this board, or you can use the original cable with a USB plug which is mentioned in the help file.

C. It should do, I removed the batteries from an original holder and inserted the LiPo easily. There is also a small circuit board to connect the battery to via a plug which also serves as the connection to the CPU board.

D. There was a discussion recently initiated by Namir [HP-25 Emulators suggestion] about adding GSB RTN capability. I added a new code GSB 49 as per the discussion. The instruction causes a jump to step 49 where the program has a GTOnn step allowing the subroutine to appear just about anywhere in a program. There are insufficient steps to have GSB's to a range of steps like the GTO instructions. It only supports one subroutine at a time.

All of the original functionality and code for the emulated models is intact so they will operate normally if desired.

E. I wish that were so, but due to the interconnect pins used by HP in the Woodstocks that is impossible without modifying the keyboard and display circuit boards. I have not been able to find replacements for these pins although I saw some that came close. Unfortunately either way, soldering is required. I know not everyone can solder, so I have offered, mentioned in the help file, to do the soldering if the pins or original maybe dead CPU boards are sent to me. If requested, what's left will be sent back with the new CPU board.

It's actually not that hard to do, maybe a bit fiddly, but to help make it a bit easier, I also supply a small circuit board template to help line the pins up while soldering.

The user manual is available in the CalCom download, (CPU_WS.pdf), if anyone wants to read through it.

cheers

Tony

[rprosperi]

Thanks for these helpful answers Tony!!

My own valuable contribution to the world of calculator electronics is to never again attempt soldering of this nature, so when ready to order I'll send you a machine to have it installed.

The idea of modifying a normal Woodstock power cable to replace the brick with a normal USB A connector is great. Simple, elegant and obvious. Well done Dave Eaton.

Looking forward to this Tony!

[MinkLib]

I read the CPU_WS.pdf with interest.

The FTDI serial link for reflashing now uses 5v. instead of 3.3v on the Spice board - why is that?
Also why (other than mechanical access) does the board have to be removed to use the serial link?
Can the calculator be powered on (again a la Spice) while serial reflashing?

An exciting new development for sure, for the trusty Woodstock family. Well done indeed, Tony.

[teenix]

(04-27-2024 10:35 AM)MinkLib Wrote:  I read the CPU_WS.pdf with interest.

The FTDI serial link for reflashing now uses 5v. instead of 3.3v on the Spice board - why is that?
Also why (other than mechanical access) does the board have to be removed to use the serial link?
Can the calculator be powered on (again a la Spice) while serial reflashing?

An exciting new development for sure, for the trusty Woodstock family. Well done indeed, Tony.

The power supply is a little bit different to the Spice. The FTDI powers the CPU board, whereas the Spice does not.

Edit: The battery is difficult to connect with the CPU/Display/Key boards removed from the case so the FTDI board supplies the power.

The 3 possible supplies all with different voltages are isolated from each other, except the battery could override. The display and Bluetooth are powered directly from the battery so while the FTDI is powering the board, or from the programmer which cannot supply enough current to drive a fully operating CPU board, they will not function. There shouldn't be issues with merging supplies, but it was a "just in case' thing.

The serial reflash is just meant as a temporary measure. For external power, the USB cable can be used via the charge connector. You can use the FTDI interface as you would the Bluetooth, to change the menu options or transfer programs via CalCom.

cheers

Tony

[teenix]

I opened up the Woodstock AC power supply and gave it a 5VDC output using a simple circuit consisting of a full bridge rectifier, 7805 regulator and a couple of caps. This allows the original charger to plug directly into the calculator to power the new Woodstock CPU board and charge the battery.

It's a bit bulky, so I'll see if I can miniaturize it to fit comfortably into the charger case.

cheers

Tony