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Panasonic RL-H1400 Restoration and project thread

I have a very cheap and damaged H1400 on the way which will most likely end up donating its ROM sockets to make programming adapters.

I have tried to find a source for the sockets and have come up empty.
 
And here is one crazy reason to make the video adapter composite. I completely forgot I had a couple of these from old projects.

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svc_headset.jpg

Of course, one better learn to touch-type on the handheld because switching focus would be headache inducing.
 
I ended up getting a decent offer on suitcase mobile radio programmer kits. These usually include the H1800 (8K version) as well as several other pieces of hard to find hardware.

I have a bit of an ambitious project started to create a (new) cassette emulator. Not just for this handheld, but for many of the computers I have with only cassette storage.

The plan is to allow playback and record along with a remote input for those systems that require it. Retro styling using only a 16x2 LCD.

I am basing it around the ESP32-A1S Audio-kit board which has a pretty steep learning curve but already has nearly everything needed built right in. So far, I have the buttons, LCD, SD card, and audio codec working. I have a mock up for the UI that I think is going to be pretty neat.

The hardest part is going to be the emulator file support (playing back and recording to!) I will be starting out with just wav file support. Anyway, here is a pic of the beginnings:

20251012_182457.jpg
 
I found that I did have the ROMS already for all of the peripherals including the TV adapter. I am beginning disassembly of the main ROM now.

In the ROM set there is the majority of the desired programs such as the basic and forth modules. Once I finally get my trashed unit and extract the sockets from it, I will be able to make an adapter to make some ROMs.

I have a second unit that is acting flaky. It suffered a little bit of battery corrosion, but it doesn't look like anything serious. I replaced the battery and wiring. It sometimes turns on and sometimes does not. When it does turn on, it acts very sluggish and unresponsive. Sometimes not responding at all to keys or a delayed response. My suspicion at the moment is that something is causing interrupt overflow. Troubleshooting this unit should get me very familiar with the hardware.

(If you are keeping count, I will end up with 4 units total including the suitcased unit)

I am still waiting on a few more parts to finish up some of the RAM expansion boards. Installation looks simple as long as getting the board out with breaking things turns out to be easy. Obviously trashed unit will be the test.

If anyone is looking for information on this unit, just ask. I have accumulated a small stash from various research back earlier this year when I was considering purchasing one.
 
re the SIMM vs SIPP tangent: Another way to use SIMMs in a SIPP motherboard is to just insert SIMM sockets in the SIPP sockets. Not sure if SIMM sockets are still readily available, but still.
 
Both the suitcase programmer and the very cheap beat-up unit are the RL-H1800 which are the 8K versions. I may end up doing some swapping around of parts to save the 8K.

So the suitcase programmer comes with a program storage module which is a box that can fit 8 eeproms. Just standard DIP sockets. Each one appears in the main menu as if they were normal modules. This will come in handy for quick development! I will explore this module some more. It would be neat to install 28 series 5V programmable flash memories or fill with NVRAM/FRAM so they could be written from the unit. Maybe even install a PicoROM for very fast cross development! Seriously you want one of those for whatever system you are messing around with.

The second unique part of it is an eeprom burner. This also has peripheral eeprom in it which then shows up in the main menu. This allows you to burn various eeproms. It has 24 pin and 18 pin ZIF sockets. It also has a DB-9 which is sadly not a serial port like I was hoping.

BTW, one way to tell if a unit is the 8K model from a front picture is that there will be an 8 printed in the lower right corner of the keyboard template. This damaged unit is one of the LOV (liberty of Virginia) units that seem to show up a lot. It might be safe to assume all of those are 8K models.

I have not opened up the io expander part yet. This allows you to connect up multiple modules at once in a tree.

The suitcase come with a much more hefty power supply to power all of the expansion modules and the tray is designed to keep all of the pieces together and not easily removable.

I have been spending some time thinking about the cross-development tool-chain. You typically need:

1. Assembler - I prefer RetroAssembler as I have used it several times due to it's large target support. It covers most processors of the 80s.
2. SnapForth - Someone industrious may be able to fork an open source Forth compiler to support SnapForth. I think among the documents there is enough information to make one.
3. Emulator - PockEmul is the only emulator available, I believe. It is not super expensive, but to fully run on the PC side, it needs a monthly $2 subscription for the cloud.
4. Some method for uploading the code to RAM inside of the unit. The cassette port is readily available and support is built in the printer which comes with most units. A program on the PC which can emulate the tape signals using a USB sound card might just be perfect.

Mass storage of some sort that can be swapped back and forth with the PC is an end-goal, but anything new that you introduce needs drivers. So that requires a means to bootstrap code. The cassette interface is an easy way to do that until ROMs are produced. So that is probably where my next effort is headed. There are already some tools to do this for the TRS-80 PC-2, so perhaps the foundation is already there.

The reason for a USB soundcard is that I can modify the outputs to match the cassette interface better. And it can be tossed into a self-contained box with just a USB connection.
 
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Re emulator:
I would guess that someone experienced in doing things with MAME might be able to adapt it to emulate this machine, perhaps?
 
MiaM said:
Re emulator:
I would guess that someone experienced in doing things with MAME might be able to adapt it to emulate this machine, perhaps?
Click to expand...
Probably. The cost for the PockEmul are not bank-busting. And once an easy transfer system is developed, an emulator becomes less important.

If I can get the PicoRom working and the fast cassette transfer working, that should make iteration fairly quick until we can reach something like an SD or CF card storage.

My goal is to bodge in the PicoRom to the Programmable Storage Module. Having that module should really start speeding things up.

The emulator is great for debugging and when modifying system and driver ROMs. Being able to watch the registers and memory during execution is helpful.
 
This is what the Program storage module looks like inside. Sockets for 8 option ROMs. These function the same as the internal modules (they show up in the menu) but allow the use of standard EEPROMs. The sockets are 28 pin. The EEPROMs installed here are D27128 (16K). I have backed up all of them. No idea if they might be useful to someone later. This kit was used to program GE mobile radios and was apparently still supported even up until around a decade ago.

The 27256 (32K) also comes in a 28 pin package. I will have to check whether that is compatible or not. It might be interesting to mod this to take FRAM, NVRAM (Timekeeper), or even RAM. With 8 slots, there is more than I would need.

From my understanding, the SnapForth and Basic ROMs require 16K Roms and originally came in modified carriers because the internal sockets only support up to 8K. So I should be able to run those on my unit with this.

20251020_030030.jpg

Closed up:

20251020_030929.jpg20251020_030936.jpg

And this is the EPROM programmer:
20251020_031035.jpg
 
So the plan is:
Install PicoRom inside the program storage module. This will require some simple modification since the PicoRom is 32 pin and the sockets are 28 pin. Nothing major. I will install a USB C panel mount to the box so that I can keep it closed. The long tray meant for the handheld and printer holds both devices. But the box does get in the way of the keyboard a bit.

Now.... the SnapForth and SnapBasic ROMS are needed for development of programs. Doing development ON the HHC is a bit cumbersome. But.... the Panasonic HHC is a 6502 based system. This means porting over the compilers to another 6502 based system should be simpler than scratch development. The original cross development kit was for the Apple II systems which makes sense. This could then be run in an emulator on a PC.

Assembly would of course just be the usual. However, some work needs to be put in to create the libraries for the hardware. This allows making use of the OS routines for driving hardware. Some is documented, but the disassembly will provide the rest.
 
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