In the late 80s I owned a Sharp PC-2500, which had a fairly complex business software package in ROM. I have no idea how I did this, since my notes are lost for 30 years, but I discovered that the BASIC dialect had an undocumented POKE command, so I started pokeing at random ... and eventually found a POKE that switched in the ROM software while remaining inside the BASIC interpreter. So the BASIC editor could be used to view the "source" of the in-ROM software! I remember writing the whole damn thing out by hand, hundreds and hundreds of lines of BASIC. Wish I'd kept it :)
Well back in the day a few of us in the RF community were hacking Motorola radio firmware. The chip you showed with the window was a common chip used by the big bad M to store their firmware. There was a company that I believe was called Andromeda Systems that made a programmer that could read and write these ROMs. Many times we would pull the roms that were socketed and read them. Those that were soldered in place had to be desoldered from the logic board and then read. Once you had the files you could develop a database with details of which radio model and options it came with. Comparison was done through hex editor programs. Of course the big M used their HC11 series micros in their own equipment but was also known to the industry is that their Microprocessor division sold these micros on the open market with all of the programming source codes. This of course opened the door to those in the RF industry and avid programmers to start hacking the firmware and customizing their own radios with options not available on low tier radios. Those days are long gone, pity.
I once got a strange computer, Z80 based with an expansion card. It was just the board and the keyboard, no case, no manuals, no info, nothing. Later I found that it was a custom made board (made for controlling complex tools like CNC, mills, etc) + extension for controling a plotter, no more than few hundreds made. It was original, no some standard like Spectrum, MSX or others Z80 computers. When connected, I found that somewere in the ROM it had BASIC, a very strange dialect, not very close to MS Basic. Also had a monitor OS in wich it booted and with the expansion card it had also the plotter program to command the motors, pen, etc and a communication program to receive/transmit data over RS232. I entred in BASIC and I peek all the 64 k of memory; in the listing I found its BASIC commands and also the commands for the plotter, comm program. It was quite a complex computer, B&W video, very few graphical commands, but it had many math commands to work with arrays. Also, it could have been used either connected to a monitor (composite video out only, no RF) or could be used with a terminal via RS232. It had RS232 port, tape port, composite video and extension interface. I do not know if it was able to run CP/M or what other peripherals it had actually, but it might had a floppy and hard disk interfaces. Also I knew that it was used to control a robotic arm in a university project. I found that someone intended to replicate it few years ago with modern ICs and if I will find the schematic I plan to build it. Maybe on that EPROM module, the "jumper" is the remains of an electrolythic capacitor?
I did a video several weeks after this one where I managed to fix the voltage regulator module. In doing so I discovered a previous fix I had done lead to the regulator being damaged.
Awesome video! Great stuff! I have a pc1500 without all that wiring inside, I might say "clean". Is it an earlier version? I'd like to know more about differences between them.
Typically, on most products the versions with bodge wires are the early versions. There are also some PC-1500s which have a 'block of goo' inside. It might be interesting to collect serial numbers of these variations to see if a trend can be found.
Ups! RIP little Sharp. We all have to go one day. Better than ending up forgotten in the trash. Gave its body to Science and UA-cam... A little sad, but it's life.
Reminds me of when I got to the back of the storage locker I had since the 80's .. I should have made a vid, or at least took notes.. this stuff ain't going to last forever...
I had not considered that. It did very much look like a jumper but it could have been the leads of a cap which was across the power rail, that makes much more sense than a jumper :)
In some cases, it may be easy to pop the case off a module and in other cases it might break the plastic. You also would need to desolder the EPROM or have a test clip of that size and hope that the address selection logic does not interfere.
In the late 80s I owned a Sharp PC-2500, which had a fairly complex business software package in ROM. I have no idea how I did this, since my notes are lost for 30 years, but I discovered that the BASIC dialect had an undocumented POKE command, so I started pokeing at random ... and eventually found a POKE that switched in the ROM software while remaining inside the BASIC interpreter. So the BASIC editor could be used to view the "source" of the in-ROM software! I remember writing the whole damn thing out by hand, hundreds and hundreds of lines of BASIC. Wish I'd kept it :)
The PC-2500 is an interesting looking machine. It is sort of like they decided to build all the parts of a pocket computer into one case.
Well back in the day a few of us in the RF community were hacking Motorola radio firmware. The chip you showed with the window was a common chip used by the big bad M to store their firmware. There was a company that I believe was called Andromeda Systems that made a programmer that could read and write these ROMs. Many times we would pull the roms that were socketed and read them. Those that were soldered in place had to be desoldered from the logic board and then read. Once you had the files you could develop a database with details of which radio model and options it came with. Comparison was done through hex editor programs. Of course the big M used their HC11 series micros in their own equipment but was also known to the industry is that their Microprocessor division sold these micros on the open market with all of the programming source codes. This of course opened the door to those in the RF industry and avid programmers to start hacking the firmware and customizing their own radios with options not available on low tier radios. Those days are long gone, pity.
I once got a strange computer, Z80 based with an expansion card. It was just the board and the keyboard, no case, no manuals, no info, nothing. Later I found that it was a custom made board (made for controlling complex tools like CNC, mills, etc) + extension for controling a plotter, no more than few hundreds made. It was original, no some standard like Spectrum, MSX or others Z80 computers.
When connected, I found that somewere in the ROM it had BASIC, a very strange dialect, not very close to MS Basic. Also had a monitor OS in wich it booted and with the expansion card it had also the plotter program to command the motors, pen, etc and a communication program to receive/transmit data over RS232. I entred in BASIC and I peek all the 64 k of memory; in the listing I found its BASIC commands and also the commands for the plotter, comm program. It was quite a complex computer, B&W video, very few graphical commands, but it had many math commands to work with arrays. Also, it could have been used either connected to a monitor (composite video out only, no RF) or could be used with a terminal via RS232. It had RS232 port, tape port, composite video and extension interface. I do not know if it was able to run CP/M or what other peripherals it had actually, but it might had a floppy and hard disk interfaces. Also I knew that it was used to control a robotic arm in a university project.
I found that someone intended to replicate it few years ago with modern ICs and if I will find the schematic I plan to build it.
Maybe on that EPROM module, the "jumper" is the remains of an electrolythic capacitor?
Interesting! And appreciate the humor too.
I'm glad at least a few folks get my sense of humor :)
Loved the treasure hunt! It must be getting cold where you live. Don't forget to bring in your brass monkeys.
You forgot the magic words Jeff! Lol!
Ah, a power supply that doubles as a fuse. Forward thinking by Sharp there... And very cool analysis on the ROMs. :)
I did a video several weeks after this one where I managed to fix the voltage regulator module. In doing so I discovered a previous fix I had done lead to the regulator being damaged.
@@HeyBirt Ouch. I'll have to go find that video. I wouldn't have thought that that was possible.
Very interesting. Would love to see more on the CE-158. Maybe a overview of its capabilities?
Sure. In fact, I have a couple that need repaired so maybe we can do a repair video and then show off how it works?
@@HeyBirt Sounds great!
Really cool video! Thanks for sharing and sorry to hear about the damage, which I hope you can repair
Awesome video! Great stuff! I have a pc1500 without all that wiring inside, I might say "clean". Is it an earlier version? I'd like to know more about differences between them.
Typically, on most products the versions with bodge wires are the early versions. There are also some PC-1500s which have a 'block of goo' inside. It might be interesting to collect serial numbers of these variations to see if a trend can be found.
Ups! RIP little Sharp. We all have to go one day. Better than ending up forgotten in the trash. Gave its body to Science and UA-cam... A little sad, but it's life.
I did manage to repair the voltage regulator module: ua-cam.com/video/HyMKcDh6A5A/v-deo.html
Really sorry to see you let the smoke out… That’s a real bummer…
DOOD that's nuts!
Reminds me of when I got to the back of the storage locker I had since the 80's .. I should have made a vid, or at least took notes.. this stuff ain't going to last forever...
Perhaps the jumper is the remains of a tantalum cap?
I had not considered that. It did very much look like a jumper but it could have been the leads of a cap which was across the power rail, that makes much more sense than a jumper :)
The ones and zeros on the die can only be seen when viewed under intense UV. 😜
I'll take it with me on my next trip to the tanning bed :)
Yeah and delete the system32 folder on windows too . Ha--ha, not
Why not just dump ROMs directly? Via EZP or similar. I think it is must have tool for digital archeology.
In some cases, it may be easy to pop the case off a module and in other cases it might break the plastic. You also would need to desolder the EPROM or have a test clip of that size and hope that the address selection logic does not interfere.
这款计算器在80年代的中国技术人员应用很普遍
I would love to find one of the Chinese made versions of the PC-1500.