Recent content by chuma

I'm having two strange issues with my Sharp PT-9000: I can't get a good read from the resistive touchscreen, and the serial port sends and receives garbage data all the time. I have a hunch (more like a wish 🙏) that these are both somehow power-related problems. Other than that the machine...

You probably already found https://kayprojournal.com/index.php/Kaypro_PC which has lots of info about this machine. It's essentially a PC/XT clone with a passive backplane instead of a motherboard. With a Raspberry Pi Pico, a level shifter (or circuitry), and a USB OTG cable, you can build an...

I'm sure that some people still do. My life is slightly complicated and I got hooked by running my own CalDAV server over a decade ago so I could easily share calendars between family members that use either iOS or Android, and didn't want to use GCal. Kinda requires using modern devices at...

I acquired the handheld collection of another local retro collector last year, and it included many PalmOS devices. I haven't catalogued them all yet but I think there's around 20 devices, ranging from a PalmPilot Pro all the way to a LifeDrive. Even some odd ones like TRGPros, Handera 330s...

I recently acquired what seems to be a real unicorn of a device, a Sharp PT-9000 tablet computer, circa 1994. It's a chunky tablet computer with a 640x400 B&W LCD paired with a resistive touch panel, that runs DOS and GeoWorks (PEN/GEOS, I guess?). The hardware is organized around the Vadem...

Could be the screen contrast - slider position or the slider component itself - though if the volume's up then the eMate should emit the start-up sound You mentioned "It has two cards in the slots" - one should be the ROM card with NewtonOS on it, it should be obvious because the card has spots...

I haven't posted any updates here because the Linux PulseAudio output driver for Einstein was killing the emulation performance. Since I hacked/wrote it, I just spent the last 1.5 weeks fixing it. Now that it no longer sucks and the emulation actually runs smoothly and at the proper speed on...

As far as I can tell, Einstein currently doesn't boot with the eMate ROM - it ends up trying to run the diagnostic image from REx0 and falls into a boot loop. Could be because Einstein applies a number of ROM patches in its JIT emulation to work around things that aren't understood or hardware...

Ah, yes, that's a good idea! I started doing that last night, though I've never used Ghidra before. I am not great at reading machine code (it's been a long time since I had to use it in university, and haven't had to use it in my career) so it's nice to get some kind of visual representation...

I ended up warming a hot/cold pack to about 45-50°C and leaving it on the screen for a few minutes. This helped convince the ancient double-sided tape holding the screen cover on to let go. Currently rebuilding the broken plastic and lubricating the hinge spring.

Read the Clean-ROM-Images link that I posted. Essentially, dumping the ROM from NewtonOS reads the ROM space through the MMU, and there happens to be a page of RAM mapped in there. This is a minor consideration, but I'm a bit pedantic ...

@Androda Yup, we're reading the same documentation. The PS-7110 is pretty close to the 7100 - the order of the internal registers between the two is very close. At that point in the boot, the MMU has not been enabled. I should actually go back and check my work ... for some reason I can't...

That's the correct-enough ROM image - it's named with the wrong version (it should be 737041) and it's not 100% clean, but it will do. I started collecting information about actual clean NewtonOS ROM dumps, now that folks have hardware which can read the chips directly...

From tracing the boot process, there is code in the DiagBootStub - a very interesting area of the ROM almost certainly written in pure assembler - that tests whether addresses can be written and then read back, starting with 0x4000000 and 0x4200000 (base RAM and base RAM + 2MB). If the test at...

Thanks to the symbol information included with debug ROM images, and a convenient tool written years ago called `mpdumper` that demangles the symbols, we can look through much of the ROM code for interesting symbols. These are good starting points for tracing code and ROM accesses from...