Yeah The D8 fault on mine definitely gave mine more issues...
I don't know why they display the voltage at that node while its charging, its rather meaningless... they could have just written charging or something similar there as well....

Since i fixed D8 I still haven't seen a low batt warning pop up when mine is on charge, only when running from battery, it shows the battery as 24**mV ish when the warning pops up... I'd expect the MCU_ADC1 line to be pretty noisy & there isn't any hardware low pass filter on the schematic before it goes into the 8051s ADC, arguably it should have one, who knows if they have done something in software.... so maybe that's it, but its hard to imagine the noise ever getting so bad that it could get as low as 24**mV from noise when the battery is fully charged....
When I get a bit more time on it Ill hook up digital storage 'scope to the battery output and MCU_ADC1 and see if I can capture what's going on (if anything) when the battery warning message pops up....

Inhibit wrote on 2025-04-05, 14:03:

javispedro1 wrote on 2025-03-26, 13:19:

I do see it all the time. While charging for the reasons you mention it appears almost constantly; while discharging it is not yet clear to me why, but it does appear, but rarely. It tends to correlate with SoC (appears more often with lower battery v) , I'd bet it is 8051 or sampling issue, after all it doesn't shut down as you say.

I never got parallel to work but I didn't try very hard; I got serial to work at least to an FTDI; the BIOS on mine is a bit buggy and will crash on even a simple echo > COM1, but raw access does work.

If you're getting the low charge message appearing while charging try a lower output charger. I switched mine out immediately for my high quality USB-C power brick and an appropriate USB-C to barrel jack. What I noticed is that my usual USB-C adapter which puts out as much amperage as it'd accept caused a constant low battery warning issue but a low power USB-C brick capable of a lower amperage didn't.

Also, I've meant to check what was going on there because that brick is capable of a (relative to what I assume that battery should charge at) *lot* of amps and I'm curious exactly how much power the Pocket 386 is drawing...

Its possibe the pocket 386 wasnt drawing enough currrent to keep the SMPS in your high power brick running all the time, it could have gone into a 'burst mode' or similar, which would allow the 12V to drop periodically...
With the lowest possible threshold voltage of MOSFET, with the battery fully charged, if the 12V line drops below 11.3V it would switch off the battery supply (9.6V with the highest threshold voltage MOSFET) - so in theory it can switch the battery in and out of circuit if the 12V supply drops by a fairly small amount....

Tritonio wrote on 2025-04-08, 11:25:

...the keyboard stays with all three light lit up and no key does anything when pressed neither on the external keyboard nor on the laptop....

Turns out it was that specific keyboard that didn't work with it. I got another one, seemingly old stock from 00's or so and it works just fine.

I am wondering if I should try to get an ISA sound card, I've eyed a Sound Blaster 16 and an AWE32, but I have no clue if those will work with it.

I'd also love to get FreeDOS working on it but the FreeDOS wiki has been down for a year now. They had a nice page about the pocket386 and how to use QEMU to format and install FreeDOS on the CompactFlash for the pocket. I wish I had saved it. It had some cylinder settings that were required, plus some startup parameter for the FreeDOS setup program that it said were required for the installation to later work with pocket386.

For any ISA card you'd need an external ISA adapter. The soundcards you mention are 16 Bit ISA slot cards, someone on this thread has made a 16 Bit ISA adapter (many soundcards need a -ve supply that the pocket386 doesnt supply, so you need to provide -5V or -12V depending on the card....), but I dont think there is a commercially available one. If you go for the 8Bit ISA adapter (ISA8-EXP-01 ) you 'may' be able to get them to work - some 16 bit cards will work in 8 bit slots with some settings, there are threads on Vogons on this...
But to be 100% sure it will work its safer to stick with cards like the original soundblaster 1, 1.5 or 2 - or clones... which only offer 8 Bit mono sound. The adapters are just bare PCBs, for everday use you really need an enclosure or at least some sort of support to protect/enclose/hold the cards, there are a few 3D printable models out there...

Ive not used QEMU, but I can say 86Box works great for installing operating systems (with the caveat that I had issues with compatibility of the virtual hard drive files and some image writing software). You just set up a virtual machine thats a close match for the Pocket 386, but add in a floppy drive or CDROM drive - whatever format your OS install disk images are on and your away...
I had issues if I selected zero wait states for the memory type, other than that it was pretty painless.
Its wise to set up a virtual hard drive with cyl/sector etc geometry that matches your compact flash card (put it in the pocket 386 and look in the BIOS hard drive autodetect, or if your quick catch it on boot), its easier to write the image then. I then use BalenaEtcher (free, use the uncompressed hard drive image type in 86Box for compatibility) to copy the hard disk 86Box image to the compact flash.
Ive done dos 6.22+ win 3.11, an early pre ie4 version of win95 (I think the early ones are faster?) & RedHat 5.2 (really, dont, just dont, its so slowwwwww) like this, on a variety of different size/types of compact flash. I havent done freedos, but I cant see why it wouldnt work, so long as you have the install disk image files (.iso)

I souldnt tempt fate, I had a crack at installing freedos using 86Box amd it hasnt been 100% straightforward:
I set up 2 hard drives, one on 0,0 as uncompressed so I could easily write the image to a compact flash later, and a second hard drive 0,1...
I did a full install freedos 1.4 including sources using the legacy option install .iso s with a boot floppy.. took hours
however on removing the floppy image from the a: drive it complained that the boot drive had no active partitions!
Ive fixed my install, but if i were to do it again from scratch i would set up 86Box with just one hard drive & after it boots from the floppy Id exit the install when it asks you if you want to proceed, then do an FDISK to set up the partions, then a FORMAT c: /s (I think you need to CD to the directory on A: with the system in).
Id then do a reboot from a: and let it proceed with the install...

The problem that was on the wiki is that freedos will install a lba/int13x boot sector on lba capable machines, but such bootsector fails miserably on the pocket386. This will likely be an issue precisely only when you use an emulator or VM to install it.

See https://www.both.org/?p=5690

I didnt even get as far as trying to boot the pocket386, it wouldnt boot in 86Box when i tested it....
very odd, if I booted from the floppy image the files seemed to be on c: & it said Freedos was already installed, though it wouldnt boot - no active partition
however after I gave in and FDISK'ed the drive, all the files were on d: ....
its as if it got mixed up with the two drives somehow.
It worked fine after I FDISK'ed to set up a partion, format /s & then xcopy 'd the contents of d: to c:
Would you expect those issues just within 86Box?

@javispedro1
Thanks, I came to try this again today & found the image wouldnt boot in 86Box or the pocket 386, I had installed more from the extras CD image, not sure if that somehow re-wrote the system files so it wouldnt boot, but certainly sys c: /force:chs fixed it!
Ive still no idea why I ended up with the files on d: and c: in the virtual machine!!!
However, on the pocket386 I had to edit the default boot file FDAUTO.BAT ;
I rem ed out the CDROM, FDNET & set balster lines, but the worst problem was with the long filename support, it caused an exception with the JEMM memory manager, so I rem 'd out the DOSLFN section.

Other than that it seems to be working OK!

Random low battery warnings
At the risk of bombarding this thread with more messages...

Ive significantly reduced the number of random shutdown/battery warnings on my pocket386, when running from the battery (warnings when runnning from the 12V external PSU was a different issue on mine...) - After my mod, Ive just run it from full battery to about 10% (num lock starts flashing, I presume this is a low batt warning?) without a single false, random warning, though I did get one when the battery was low yesterday...
I'd measured the noise on the MCU_ADC1 line (switched output of the battery, input to the +5V regulator) There was a 350mV switching spike on it together with various other switching/PSU noise... This may well get larger at other times, I only had a quick look. It may not seem like much , but in the context of the difference from full battery voltage to flat being about 800mV....
The designer is clearly aware its often a good idea to bypass the electrolytics on the switching regs with an SMD ceramic cap - they have elsewhere, but not on C23.....
Ive soldered a 1uF 1206 (size not critical, smaller size like 0805 might be a bit easier to fit) ceramic cap across the pins of C23 on the through hole solderside... I did the same with C21, C22 (despite the pic I posted, solder joint on mine was OK) is a long way from C21 on the PCB, one directly across the pins isnt a bad idea while youve got the PCB out....
This is a relatively easy mod - just be careful not to solder through the solder resist on the PCB and cause a short - If in doubt its a good idea to meter across the cap after to check there is no short
This totally deals with the 350mV switching spike, approx halving the peak to peak value of the noise at this circuit node when I measured it . I suspect that as the switch spikes are brief it only coincides with the 8051 ADC sampling the voltage on rare, random occasions - hence the random nature of the warnings....

As I did see one false warning yesterday (though the battery was pretty low TBF) I may consider another mod as well as these caps, to filter the noise at this node, but this would require cutting a track.... So Ill prob just see how good the improvement from the caps is for now...

So the same guy has now created an FPGA-based alternative to the pocket 386 and 8086, called the "OneChipBook" -- https://www.tindie.com/products/cycle/onechip … pment-platform/ .

I would have really liked to love this as a pocket386 successor -- 4:3, better screen (iPad leftovers?), and looks like better keyboard -- unfortunately I think it shares many of the same cons as the pocket386 (the same non-configurable µc handles the keyboard and OSD), but has an even worse con: the FPGA used is really ancient. I have to go back to 2013 to find design software that supports this model (the chip itself from 2008 or so).

I believe the intended audience was just as a "MSX laptop" and I suppose there's some MSX core floating around that can fit in this FPGA, but I rather doubt a PC-core like a0486 or similar is even thinkable. Maybe someone with an older quartus version wants to try if at least one of the much simpler 8086 cores can fit at reasonable performance...
So oh well, I think I'll pass. Even though I do like the concept and would enjoy one with say a MISTER-like FPGA.

They must really love using left-over parts.

@javispedro1 the thing is intended for MSX - it's original name when it was released back in Feb was "MSX Book" before changing into OneChipBook.

Is there a list of 'cores' currently available for the Cyclone EP1C12Q? I did try google but failed. I'm not that familiar with FPGA's, just curious what beyond MSX could be loaded without being a developer.

Ive been looking out of curiosity, Im not an FPGA guy either... but there seems to be lots of 8bit core options that would fit & s80x86 or MCL86 should go - whilst they might run fast im not sure the speed would be much use without the instruction set and protected modes etc of a 386 or above core...
https://opencores.org/projects/ao486 looks huge (sound seems to take up alot!) & takes up 80% of a 4th gen Cyclone - this is a 1st gen!
FX68k core looks like it would take under half the LES, so a system based on that might be doable...
I guess some level of 'developer' skills would be needed for anything other than a MSX, even with one of the full system level implemantations out there?

I've simply swapped cf cards that I formatted, set up with os and files and used in regular 386/486 machines over to the pocket 386 without any issues, so maybe that is an easier way to configure a new bootable cf if you need one.

I recommend the picogus for the isa expansion (it also provides sound blaster emulation). I have tested it with mine and it works well.

hi, my pocket386's rtc loses minutes, in an hour it stays like 3 minutes behind, and nearly all real mode games like grand prix circuit have a weird bug where the pc speaker freezes and hangs but the rest of the game works with this loud beep playing, what can it be?