Nice upload! 👍 According to the datasheet, the TC5516APL has a standby current at 25degC of 0.2uA! So a mere 1.7mAh/year, its quite possible the backup battery has kept its contents all this time...
That's some really cool and robust computer! I can only imagine the splendid touchyfeeliness of its keyboard, it's just beautiful. To the VCF with it, please :)
That keyboard is probably a Keytronic foam and foil type. The foam in those has a tendency to deteriorate, and then keypresses won't register. Best way of fixing that is to make new foam-pads for each key.
Wow, when they said non-volatile, they sure weren't messing around! My initial thought was that since it was a terminal, maybe it was something silly like a local echo setting preventing the cursor from moving, but looking at that manual it's a weirder thing entirely. It almost seems more like a word processor that's made to transmit the text in the buffer all at once when you whack xmit. Which I guess matches up with the letter the former Xitron employee wrote. Yes, the port is to hook something else up to, it's just a plain old RS-232 serial port and you can see that the switch is set to RS-232. I presume if you flip it to modem you can try to see if the coupler will make beep beep noises. If you can figure out what's up with the keyboard, you might be able to get that to talk to another modem with the coupler and an old handset!
My first thought on the 'dead' keyboard, is it's defaulting to sending keystrokes out the serial port - I havent tried to read that manual you showed, I'm just assuming there is a toggle between local and remote operations somewhere and its currently in remote.
Well, it came through the e-waste stream a couple of years ago and has been sitting on a shelf ever since. I finally decided to give it a little showcase. Thanks for watching and for the comment.
there's 8 of these 2k RAM chips so 16k of battery-backed RAM (although yeah sure the battery may or may not be connected to all of them) so there's almost certainly gonna be a lot more text stored in those ICs. Don't unplug the battery or any of these ICs before you have a chance to dump them. You should do that relatively soon (don't let it sit for another decade or two because who knows how long that battery will last) (that RS232 port is probably still gonna be the most convenient method of doing that - gotta fix that keyboard. The computer part is highly likely to work as it will have to initialize the CRTC if there is one and copy the memory contents to video RAM. From the fact some of the LEDs extinguish after a second on powerup, the CPU is almost certainly working) (you should also eventually dump the ROMs which are socketed and sit next to the battery backed RAM chips - these can go bad with age as well, so dump them while they're working. I've dumped the ROMs of a prototype pinball machine which wouldn't run with the ROMs of the production model - the solenoid drivers were on a different address in CPU space - a few years later one of the ROMs died. Good I had it backed up, it was likely the only copy on earth.) These 2k SRAM chips were pretty popular for low power/battery backup SRAM, but not used for that exclusively. I've seen those used in arcade machines for mixed uses (high score saves, just plain RAM, Video RAM) btw. AFAIK bubble memory needs to warm up which takes longer than the CRT to warm up so there being text on the screen right away means no bubble memory in the system. Lol at hit the dislike button twice
It would be interesting to know the typical life of the batteries that were installed in these systems. At the power draw of these chips its possible that they could keep the memory stable a long time. Need to see also if the battery is one of those that is rechargeable. It could be that occasionally plugging in the system might be boosting the battery extending the time it can keep the memory alive.
@@8BitDoodads-sm6tj It looks like a non rechargeable 3V lithium battery. Those very rarely leak (except in Apple Macintoshes) and if they do, you'll be having a really bad day. Rechargeable batteries from that time 1) self discharge much quicker, they can hold a charge for maybe 3 years at best 2) are almost guaranteed to have leaked. The only rechargeable battery I've seen that didn't leak after 40 years are Yuasa branded. I have a cocktail arcade machine from 1982 with a horse gambling game (no interactivity, you just can place bets and that's it) that uses a similar 3V lithium barrel battery which still has enough juice left in it to keep the memory intact. And almost all my SNES games still have working coin cells (for some reason, the one in Yoshi's Island died after just a few years). Turning the system on will keep the battery from draining as the RAM will run off 5V no matter if the battery is rechargeable or not. Besides, these RAM chips need a lot more current when running (in which case the battery would last "only" a year or two because they still take next to no current to operate)
@@8BitDoodads-sm6tj - As a young engineer, I believe the company Xicor sent me Non Volatile RAMs as samples which I am not sure where they went to this day... However I would look for them on that board, because they really were non volatile back in the day but expensive. Go through the chips and see if any of their chips are in there or Japanese competitors products.
I suspect that the processor isn't running and the display is showing whatever it last showed when the machine was switched off. CMOS static RAM draws very little current and it is possible that the battery kept it going all this time. It would be interesting to make it work properly and perhaps see what else is in the memory. If you fancy having a go, start with the basics (power, clock and reset) and work from there. Good luck!
I think the dual RS-232/model interface on this was because the built in model is acoustical and the RS-232 port would allow you to plug in a higher baud rate telephone line interface. Also it could be used in a newsroom that had RS-232 upload ports.
Nice upload! 👍 According to the datasheet, the TC5516APL has a standby current at 25degC of 0.2uA! So a mere 1.7mAh/year, its quite possible the backup battery has kept its contents all this time...
Wow. That would be incredible.
Or all the text on the screen has been stored in the bubble memory - otherwise whats the bubble memory for.
That's some really cool and robust computer! I can only imagine the splendid touchyfeeliness of its keyboard, it's just beautiful. To the VCF with it, please :)
That keyboard is probably a Keytronic foam and foil type. The foam in those has a tendency to deteriorate, and then keypresses won't register. Best way of fixing that is to make new foam-pads for each key.
Unfortunately you are probably right. I have another keyboard with the same malady so will probably have to tackle them both at some time.
Wow, when they said non-volatile, they sure weren't messing around!
My initial thought was that since it was a terminal, maybe it was something silly like a local echo setting preventing the cursor from moving, but looking at that manual it's a weirder thing entirely. It almost seems more like a word processor that's made to transmit the text in the buffer all at once when you whack xmit. Which I guess matches up with the letter the former Xitron employee wrote.
Yes, the port is to hook something else up to, it's just a plain old RS-232 serial port and you can see that the switch is set to RS-232. I presume if you flip it to modem you can try to see if the coupler will make beep beep noises. If you can figure out what's up with the keyboard, you might be able to get that to talk to another modem with the coupler and an old handset!
Thanks for the suggestions. Might have to try those out.
My first thought on the 'dead' keyboard, is it's defaulting to sending keystrokes out the serial port - I havent tried to read that manual you showed, I'm just assuming there is a toggle between local and remote operations somewhere and its currently in remote.
Awesome find. Where did you find it?
Well, it came through the e-waste stream a couple of years ago and has been sitting on a shelf ever since. I finally decided to give it a little showcase. Thanks for watching and for the comment.
there's 8 of these 2k RAM chips so 16k of battery-backed RAM (although yeah sure the battery may or may not be connected to all of them) so there's almost certainly gonna be a lot more text stored in those ICs. Don't unplug the battery or any of these ICs before you have a chance to dump them. You should do that relatively soon (don't let it sit for another decade or two because who knows how long that battery will last)
(that RS232 port is probably still gonna be the most convenient method of doing that - gotta fix that keyboard. The computer part is highly likely to work as it will have to initialize the CRTC if there is one and copy the memory contents to video RAM. From the fact some of the LEDs extinguish after a second on powerup, the CPU is almost certainly working)
(you should also eventually dump the ROMs which are socketed and sit next to the battery backed RAM chips - these can go bad with age as well, so dump them while they're working. I've dumped the ROMs of a prototype pinball machine which wouldn't run with the ROMs of the production model - the solenoid drivers were on a different address in CPU space - a few years later one of the ROMs died. Good I had it backed up, it was likely the only copy on earth.)
These 2k SRAM chips were pretty popular for low power/battery backup SRAM, but not used for that exclusively. I've seen those used in arcade machines for mixed uses (high score saves, just plain RAM, Video RAM)
btw. AFAIK bubble memory needs to warm up which takes longer than the CRT to warm up so there being text on the screen right away means no bubble memory in the system.
Lol at hit the dislike button twice
Thanks for all of that great information and suggestions! I will be putting those things to work very soon.
It would be interesting to know the typical life of the batteries that were installed in these systems. At the power draw of these chips its possible that they could keep the memory stable a long time. Need to see also if the battery is one of those that is rechargeable. It could be that occasionally plugging in the system might be boosting the battery extending the time it can keep the memory alive.
@@8BitDoodads-sm6tj It looks like a non rechargeable 3V lithium battery. Those very rarely leak (except in Apple Macintoshes) and if they do, you'll be having a really bad day.
Rechargeable batteries from that time 1) self discharge much quicker, they can hold a charge for maybe 3 years at best 2) are almost guaranteed to have leaked.
The only rechargeable battery I've seen that didn't leak after 40 years are Yuasa branded.
I have a cocktail arcade machine from 1982 with a horse gambling game (no interactivity, you just can place bets and that's it) that uses a similar 3V lithium barrel battery which still has enough juice left in it to keep the memory intact.
And almost all my SNES games still have working coin cells (for some reason, the one in Yoshi's Island died after just a few years).
Turning the system on will keep the battery from draining as the RAM will run off 5V no matter if the battery is rechargeable or not.
Besides, these RAM chips need a lot more current when running (in which case the battery would last "only" a year or two because they still take next to no current to operate)
@@8BitDoodads-sm6tj - As a young engineer, I believe the company Xicor sent me Non Volatile RAMs as samples which I am not sure where they went to this day... However I would look for them on that board, because they really were non volatile back in the day but expensive. Go through the chips and see if any of their chips are in there or Japanese competitors products.
I suspect that the processor isn't running and the display is showing whatever it last showed when the machine was switched off. CMOS static RAM draws very little current and it is possible that the battery kept it going all this time. It would be interesting to make it work properly and perhaps see what else is in the memory. If you fancy having a go, start with the basics (power, clock and reset) and work from there. Good luck!
Or what's on the screen is coming from the bubble memory
What a time capsule.
Yeah, it was pretty fun to unravel.
that port next to the modem looks like and most likely an RS-232 serrial port
Good eye. Yes.
I think the dual RS-232/model interface on this was because the built in model is acoustical and the RS-232 port would allow you to plug in a higher baud rate telephone line interface. Also it could be used in a newsroom that had RS-232 upload ports.