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- Опубликовано: 11 ноя 2012
- Retro teardown of the 1987 Cambridge Z88 notebook computer from Clive Sinclair
Running the OZ operating system, Pipedream application, and BBC BASIC
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Did a little double take when you mentioned Richard Russell! I remember interacting with him a bit on forums a few years ago and knew he'd written the BBC BASIC for Windows software, but didn't realise it was his from the start! More recently he developed software to restore colour to old Doctor Who episodes from the chroma dots stored on the 16mm monochrome telerecordings used for overseas transmissions. A very clever chap!
Great comment on Richard Russell's work on recovering the old Doctor Who episodes. I've just done some searching on the subject and it looks like there's a fascinating story there that needs to be looked into! Thanks.
It wasn't: Sophie Wilson wrote the first BBC BASIC in 6502 assembler, and Richard made a Z80 version of that. Oddly, he copied the documented behaviour, but didn't look at the code at all. He went on to produce BB4W (BBC BASIC for Windows), which works in a different way with many extensions. That now has versions for Mac, Linux, and even Android! Meanwhile, Sophie's BASIC also got extended, and was part of the reason the Raspberry Pi got made. So you can run both versions on one, and they're both free.
I was in the production line making these in Scotland
Timex? I was across the road at the Apprentice training centre at the time.
Designed in England. Built with cheap labour ;-)
snowballed4 What’s wrong? Could they not assemble it in England cheap enough?
@@MsArion246 It was a bit of banter. Don't stress. The Scots are always welcome here, especially if on a motorcycle. Keep safe fella
I am really thankful to have this guy spend so much time making these videos for me to learn while being an EE student in college.
Thanks for this video, Mate. Brought back a lot of memories! :-)
How does it feel, that you have gazilion times more processing power in this chineese Rigol scope, than in this computer :)
The little button on the left is reset. You shouldn't press it, generally.
To switch the machine on, press both shift keys. The way it tells you to, first thing on the metal plaque under the screen! Yes, it probably auto-powered off after a few minutes, that's an option you can set.
The little "hidden" button near the bottom is because there's a piece missing, there should be a cover door for the cartridges, that swings out. The button detects if it's open or not. Resetting with the door open performs HARD RESET, which zaps everything. Last resort!
With the door closed is SOFT RESET, which you also shouldn't need much, but it generally preserves the contents of RAM, although there's a little caveat with ":RAM.-" (yes, colon - RAM - dot dash) , it's temporary store. Any files in there during reset can cause a hang. It's a bug, they fixed it in later ROM versions, but many of the shipped Z88's were earlier ones.
You really ought to read the manual for this, it's a great, fantastic little computer. It'd also answer a lot of questions. The screen is 640x64, with graphical access that some games used. Full-screen bitmap graphics, too, though it also supports fonts in the screen controller itself. It's a supertwist, for clarity, and supports a grey level as well as full black (actually, blue).
It's a very sophisticated machine, with a sophisticated OS. Was multi-tasking, with one task at a time, but the others suspended in RAM.
Finally (for now!) the RAM in the 128K cart was a strange type called PSRAM, pseudo-static. As in it's actually dynamic (nice and cheap!) but has it's own refresh circuitry on-chip. So you can treat it, and access it, like SRAM from the outside. Downside is higher power consumption than real SRAM, and slower. Upside is cost, obviously, since it's a Sinclair!
The supercap could preserve memory (and therefore your files) for about 2 minutes on a bare machine, about 1 minute with RAM in the cart slot.
I got one of these for xmas as a kid, and I loved it to death! Since left behind in a move, which I'm sad about. I even sometimes have dreams where I find the rare version with a colour screen. Which doesn't actually exist, of course. Shame! In the dream it uses that weird colour LCD some old calculators and watches used, the one with 4 colours and no backlight. The strange orange-red, green, and blue. And "clear" is the fourth colour. I once found out the name of that kind of LCD, then forgot it. Somebody still makes them. But it was a dream, so never mind.
It's a lot of fun, and for a long while into the 1990s at least journalists would prize these, on the lookout for second-hand models, because they have so many advantages. Still do, if you want to take notes and do a bit of basic word processing.
The manual for this should still be online, a few years ago at least there were Z88 sites on the web, and one company (Rakewell) still selling them. There's also an emulator, also a few years old, and a few games and bits of software archived.
The Z80 doesn't need a 5V regulator because it's CMOS, otherwise it'd suck the batteries dry too quickly. Surprised you didn't figure that out. For someone who's got so much test equipment, you tend to jump to quick conclusions a lot in your teardowns, and not just in this one.
The NEC chip is the ULA that does basically everything that isn't CPU or memory. Standard Clive Sinclair design feature.
Also... don't insert and remove cartridges while it's conscious. It HATES that! Will generally cause a hang. No hot-swapping!
Obviously removing the RAM cart at all will cause it to lose it's contents pretty much instantly. No battery.
The machine's internal RAM is 32K. Adding the 128K cart expands the working RAM for the machine's OS and applications, as well as leaving the rest for file storage. You can store files in :RAM.0, the internal RAM, but should really use :RAM.1, the cartridge RAM, since you have it.
The expanded working RAM affects BASIC, and the document size you can open in Pipedream. Pipedream is weird, and genius, btw. It's a spreadsheet, technically, but also a word processor. If you write a letter, technically it's all stored in cell A1, which shows through on the whole screen as long as you don't use the other cells for anything. So by selectively ignoring whichever function you don't want to use, it's a word processor or spreadsheet. It supports the usual spreadsheet functions you'd have in 1987.
Also has a terminal, VT-52, for that serial port, so you could use it with Linux on your PC if you wanted to. I used to divert control of MS-DOS to it, just for fun, sometimes. Was no Linux back then.
So much for "finally" earlier. I just really love this thing. Wish I still had all the old BASIC stuff I wrote on it.
As far as "dodgy construction" goes, still works doesn't it? Show me your cellphone in 30 years, or your laptop, or, well, pretty much anything else in your house made nowadays.
somebody seems a bit butthurt over nothing. also i don't know why you're picking up on the "dodgy construction" part when he clearly stated this is how everyone did it at the time.
this video is just a teardown, obviously not a documentary on the build of the z88.
I belive You are the only man who is disappointed when something works.
WOW, I used to use those in school, and I am only like 19. Did not know my schools equipment was that old.
For its time it must have been a tremendous portable and affordable computer.
I took data processing in college in the late 70's, we were punching holes in paper IBM cards.
The d65031g is a gate array, presumably "glue logic" as you suggest. The inductor looks to be part of a cunning (though not outstandingly reliable) circuit for generating various supply voltages similar to that used in the Spectrum. There are Spectrum schematics available on the net if you are interested.
I did a lot of programming on this in the late 80. You could include machine code in the basic which I used for protection. Loved the machine but hated the keyboard. Accidentally ripped off the shift key when I was moving it.
We used them for route control for convoys in the army.
Great machine.
Wow, great to see this video...I had one of these when I was at college. Did all my college reports with it.
I am pretty sure the dead period was a hardware interrupt for the screen refresh. I have a Workslate Portable computer (spreadsheet really) from 1983 and that is all surface mount.
Just found my Z88 s/n 000037 on which I created H&V programs. Put new Duracells in - completely dead! Despite many H & S resets nothing. So when I found your video I thought fantastic, I will follow your trouble shooting. Then yours started to work! - Oh No! - ho hum. But you had given me confidence enough to undo those nine screws and get at the works for visual inspection. (I was worried the keyboard was going to explode into a million bits). I checked the batteries were connecting at each end and then did a Hard reset. The screen suddenly blinked on. WOW - Brilliant! I now have to find where I saved my programs on the eprom. It's running BBC BASIC (Z80) Version 3.00. Many, thanks thanks!!
Good on ya
Your workshop looks like a techies heaven
Awesome, made in Scotland. SCI was a big player back in the day, some of the last Amiga 1200's were made by them.
I know this is an old post now but I just thought I'd mention it, SW2 was actually meant to be operated by a plastic cover that went over the cartridge bay to prevent hot-swapping of the cartridges.
If you had to punctuate your sentences, Australia would run out of full stops!
I bought one. I was so impressed I bought a second as a backup unit. I self-taught myself through a book on RS-232. My first attempt and success was to interface my Z88 to my Toshiba 1200FB (2 diskette drives, no hard disk and only had a "hard disk" simulated in memory - the hard disk was shocking as it stored a file with almost no allocation size penalty!). You switched the Z88 on by pressing BOTH shift keys simultaneously. Same way to switch off. Then disaster struck. The membrane keyboard developed shorts. No way to turn on except to press the soft reset. And no way to turn off. I replaced that membrane but that also failed soon. I really liked it for taking noted but there was no way around the keyboard problem. I still have those two units - - - somewhere.
I had one of these to run as a dumb terminal, worked kinda, often just flexing the case slightly would lead to the 'computer' resetting or doing something equally frustrating, especially when in the middle of a lengthy basic program, oh well good memories. Thanks Dave.
I'm putting off an electronic engineering assignment for this, damn you Dave.
How ironic, BBC Basic on a 'Sinclair' machine.
Clive Zinclaire. You'd think he can't spell his own name, but Amstrad bought Sinclair shortly before. It's amazing how fast the computer development is today. We get new hardware so fast now, while these old systems were on the market for years upon years without updates. I'm also still amazed when I think of all the happy hours I spent with the C64 and the Amiga 500, which had no harddrive - at all. Today we say "lame" to anything below a Terabyte. I wonder if we'll see true icons like these computers any more. I think the best stuff today is made by small companies, like the #Open Pandora or the follow up Pyra. I'm really more impressed with these companies than with the latest iPad and all the Apple hype.
4 years behind with this but the kit is 30 years old...
The Z88 continued in use for a long time after it should have been obsolete simply because it addressed a specialist need better than later devices. If all you need to do is some basic text entry and editing on the move (as was the case for journalists) then the Z88 fitted the bill with some added advantages: lightweight, a silent keyboard, 20 hour battery life and using standard AA batteries meant that you could keep working practically forever, as the are virtually ubiquitous.
Incidentally, the edge connector expansion port was blanked off in later revisions and there was never anything produced (commercially) that used it. Really, the idea of adding external expansion devices didn't sit too well with the super-portable design concept. The only time I could see it being used would be back at your desk to maybe plug into a docking port type of system, but this was never implemented.
first connector is a parallel port used for printers and additional controller and serial port is actually a monochrome monitor video output
I wonder if those Varta batteries are originals. I was a broadband and telephone technician for Sky TV and we'd see them in older and cheaper cordless phones. Hmm it would be interesting to know that.
Dear friend, the Z88 had a resolution of 640 (80 chars) by 8. I think it was 64 pixels high. I truly fell in love with it first time I saw it and it worked so well with the Macintosh that there was really no argument to be had even! Sadly it was buggy as all heck. The common pc translator wasn't very good and not only was it slow but it worked poorly. Once then I have seen one programmer came out with a python version of the translator which worked truly wonderfully. The big problem is that you really depend on your memory a lot and that is never a good idea. Well good luck to the rest of us! May our computers work long into the night and bring us great joy and productivity! I noticed that these computers provide a functionality that was just never available way back in the day. I haven't given up. I'm still using mine!
OZ - reminded about Sharp Organisers, although they were prefixed ZQ
outside the USA. The ZQ-770 can be programmed in BASIC, but you have to
write the programs on a PC and download them. Small enough to fit in
your jacket pocket but big enough not to be fiddly, good ergonomics. 3MB
flash memory.
And at 08:10 you can see the red tails from the keyboard I designed - and it was a bitch to do because of the small amount of area left for tracking after the switch areas. It is a multi-layer silk screen printed thick film circuit...
At 14:42 on the right, is that a surface mount part sitting on top of a through-hole part? Old school, gotta love it.
Great video Dave! Unfortunately I did have the privilage to learn with these kinds of platforms.., first computer was an IBM with all through-hole components (all socketed!) with CRT... I would have gotten a kick out of that (maybe still would? haha).
YAS! MADE IN SCOTLAND, FROM GIRDERS.
SCI Systems at the time was the worlds largest contract manufacturer. This will have been made at their plant in Irvine. We used to do a lot of tech manufacturing here but in the mid 90s there was some bad blood between the government and some of the tech companies and they all suddenly upped and left, basically ruining our tech economy. For a while the central belt of Scotland was referred to a "Silicon Glen" because it was so popular with the tech giants.
Hello mate...I thought you told me doing a computer teardown would be toooo boring!! lol
Thanks!
That quiet time on the clock may be a pause while the SRAM is refreshed.
Is it a coincidence that this video showed up at 10:04 (Eastern standard time anyway)on November 12th and you had a back to the future reference?
I'd forgot about these things. I vaguely remember seeing them in stores and in computer mags, I think my parents accountant might have had one. Anyways, great vid as always Dave, love these teardowns.
I still have a working one of these
Interesting to see the LCD block and FFC - they could easily have added a hinge for the LCD to be a bit more convenient to read...
This was a typical Clive Sinclair project... so everything was built down to a price. All his computer projects were the same, make it cheap, sell it cheap. 😁
I first learned about computers on a Z80....learned op code and bin placement on Z80! Brings back alot of old memory's! They are very simple computers. Not as complex as intel 80's or moto 68's. Super easy to learn. Why it's went away I do not know.
SRAM doesn't need refreshing, it's static.
'They can run off the sniff of an oily rag.' That's fantastic. :-D
Both shift keys, now that's intuitive! :->
Man, those EEPROM packs are pretty cool.
No no: Those original ones were just EPROMs. You can get EEPROM ones now, up to the full 4Mb.
That inductor might be part of a charge pump for the serial port, as that port as you might know requires 12 volts +/- to operate. Just an educated guess.
way too cool Would Love to have this computer,working with Eproms.
If that's a RS-232 then that inductor must be a part of a SMPS, remember RS-232 has differential signaling so it must have a negative voltage supply :-)
@ 14:42 is that a surface mount capacitor inside the body of a zener diode? Looks like it.
Maybe the inductor was used to help generate the required voltage for programming the EPROM's?
The Z88's display resolution is quite impressive...
what is the max size of EPROM today?
Love the show, but a quick question. Do you get Varta batteries by the box load? They seem to be your battery of choice :)
Sinclair was a notorious hacker... it might be to do with screen writing/LCD refresh. I seem to recall they did something similar with the ZX series (after the ZX80, which basically stopped writing to screen when it wasn't idling.)
do you normally talk with your friends doing these stops while talking?
Maybe they also put that bar on the back to stiffen up the board so it will not flex when using that right expansion connector?
Possible heat sink
Richard Russell didn't write BBC BASIC for the BBC Micro, he wrote versions for Z80 CPU-based machines (and later ported his version to many other platforms). Sophie Wilson wrote the original BBC BASIC. She also designed the ARM CPU, which is used widely these days, and will likely supersede the Intel/AMD x86 family. Where did you read that R. T. Russell invented BBC BASIC?
Maybe it was said before, but I'd guess the dead-zones were checks for interrupts(keyboard and the like).
PhrontDoor i think it was doing IO too, but my guess is that it's waiting on the lcd driver.
9:34 the switch down there is not there to be pressed by a finger, but to check if the card buses cover is opened or not. Its crucial for example to have it open when you do the hard reset. Please read something about the computer before you do any review
z90 longest running cpu in history , they still sale them brand new to this day , and they are used in many system to this day , GBA did use a z90 :) , 80486 CPU was made to just unto a short bit ago.
Z80, not Z90.
look below the serial connector, at that diode or whatever, its like a smd cap inside a glass tube
Hi fi Scotland right back it ye! Gid tae see that label. Widna mind a few mair like it.
Oh the memories
12:30 yes, you have no clue about most of the stuff. Its CMOS gate array, quite common one these days
The Z88 is still being maintained with new software (operating system ROM and 3rd party applications), including file transfer desktop apps for Linux, Mac OS X and Windows.
More details here: cambridgez88.jira.com/wiki/
Perhaps the "fault" was just the contrast dial being all the way up...?
I still have 3 more lab reports to write up... hahaha. Nope. Not now, busy researching. :D
I had one of these... Traded it for a 386DX 33....
That thing is much slower than my first computer :)) i first had it in 1999 and it haved a 7 MHz CPU and 2MB of ram :)) it hardly run Windows 95 with lots of crashes . its PSU was lit on fire and the other components just started smoking and some PCB traces lit up :)) i still have its Motherboard somewhere in the house , i keep it as a memory :))
+Electronics Video Blog my first computer had 16K of ram. I was 4 and my parents where bad asses.
Grover Asylum LoL it was something :))
:))
Is the supercapacitor used for writting data on those eprom cartridges or just backup for the ram and/or clock?
It provides power while you change the batteries. If you have a mains power supply plugged in, that doesn't matter. But if you're on the road somewhere, the supercap does a fine job. You get about 2 minutes, with a bare machine, to change the batteries. Obviously you have to switch the machine "off" (actually just into low-power sleep mode) first. Then once it's sleeping, you change the batteries.
2 minutes for a bare machine, but if you have RAM carts in either of the slots, it goes down to around 1 minute for one, or about 40 seconds with 2. Still plenty of time in practice, just have your 4 x AAs ready, and concentrate on which batteries you're replacing with which.
The EPROM writer I'm not sure, but the technical reference for the Z88 is on the web and does explain, I just can't remember. It uses a 12V generator. The manual advises you not to use slot 3 for RAM, or other carts, EPROM only. This is because the 12V generator is engaged all the time the slot is occupied. So probably best not to use it at all unless you're writing EPROM.
The EPROM doesn't show up as part of the filing system. Instead, there's separate options in the File Manager (called "Filer") program, to copy files to and from EPROM, from and to other RAM carts or the machine's own RAM storage.
You get 4 devices, :RAM.0 (some of the internal 32K RAM used as file space), :RAM.1 (RAM cart in first slot), :RAM.2 (second slot), and :RAM.3 (work it out yourself).
As well, there's :RAM.- (colon RAM dot hyphen), used as temporary storage. A bug in the ROMs in most shipped machines means that :RAM.- must be empty on resetting the machine, or else it can lock up. So every reset, a good tip is to check :RAM.- and delete any files. It's not used much anyway so there's usually no real problem. :RAM.- can physically store it's data in any of the slots, or the internal RAM. The user isn't informed where.
:RAM.0 is the machine's own 32K RAM, as used for storage. It's shared with the operating RAM used by the machine's OS and programs. By itself the machine is usable but you really need 128K in slot 1 to be practical, most people bought a pack with a 128K cart included. Plugging it into :RAM.1 extended the working memory available for BASIC (from 8K to 40K), and the document size for Pipedream, the word-processor / spreadsheet miracle. 128K should be plenty for most users.
Data in RAM will die without power. Only backup is to EPROM carts, or there is a terminal emulator and separate file transfer program (XMODEM etc), so you can send files down the serial port to a host computer. At least one company made a disk drive that connected to the serial port, the same disk drive was also marketed for the Radio Shack portable mentioned earlier. The disk drive ran on it's own batteries. Back then you're talking a couple of hundred quid for it. Last floppy drive I bought was 3 quid brand new! That was for a PC, but still. They used to cost hundreds back in the 8-bit days, often more than the computer. Aaahh, I used to dream about floppy drives.
Thumbs up if you had a zx81. :) I had the whopping 16kb expander memory for it. That's probably what the side cartridge slot on this was for.
Hi, since the company is now defunct, where can I find parts for this machine i.e. a replacement keyboard
5 years late, but: www.rakewell.com/z88/z88.shtml
Yes, that was the future coming. My first digital recorded texts. When there is nothing ( no thing ), anything ( a nice thing ) is something.
How much are these worth nowadays in working order?
Let me sleep Dave... 04:08 AM here in germany.
12:00 no, switch at the bay is not hard reset!
Lol my school still has those
No, to the right of that, past the transistor. Just before the diode.
Shooting it right now...
You think it looks boring? I'd bone this Z88 if I ever got near one, and I'm a 90's child...
Inductance of thin and wide link is much less than inductunce of wire. Maybe this is the point of this big copper link.
I used to work outside Glasgow. I am now proficient in all major dialects of Scottish - angry, drunken, ned and small child :-)
Scottish kiddie slang is ... unique.
At a high enough temp lead reacts with air to create lead oxide and it does become airborne...just not at temperatures a soldering iron will get to. Also, people seem to forget that when lead isn't really hot, it's almost completely inert. Paranoia.
Maybe one the cartridges was faulty which made it not work?
as if the sold-everywhere 35/65 solder didn't contain lead......
Lead isn't absorbed as a pure element, but as a lead compound, say oxide, sulfide, etc, lead reacts with the humidity of the heads and that's how yuo get lead poisoning (like when lead oxide (white) was used as makeover), also lead isn't volatile so it has no smell, hence you can't breath lead. Compounds may have smell but it's negligible. It's not he same to smell it than puting it in your skin (and that took years to kill)
Ah, the little green inductors.
10:20, not its not even Z80 or Z80A you should learn how to read ICs types. Its CMOS 4MHz suitable for low-power application.
Actually, it IS a Zilog Z80A processor. Are you saying the designers of the Z88 were lying to us about the CPU? You do know what CMOS stands for? 🙄
@@another3997 yes I know, but you don’t. Z80 and Z80A are NMOS. Inside it’s cmos version, should be labeled like z8400pec4 or so.
@ 15:14 Biggest, Baddest SMD 0R resistor in existence.
Only man alive to get upset because something works right lol
If anyone can help the the Wikipedia article on SCI (Sanmina-SCI_Corporation), that would be grand.
Slients keys :) no cheap as possible :P
wheres your anti static wrist band :P
SKS is SK5.
My dad had a thick Glaswegian accent so I gained an unusual skill early in life.
Overclock it!
If you want to do a troubleshooting video I can send you an old laptop. When I say old I mean old it is about 1980s I have a good idea what is wrong with it but not 100% sure. It is about 2 times as thick as the old Dell Thinkpads.
I had a similar much smaller Casio PB-1000 portable computer with basic language. In practice all these portable computers of late 80's and early 90's where just very advanced programmable scientific calculators.
The programs in its internal memory could perform very complex calculations with many many adjustable parameters.
Very usefully for scientists.
Very boring for ordinary users and young students.
However today even the most advanced smartphones like iPhones or top android models doesn't permit the writing and execution directly without the use of external computers or servers. There are some apps with basic or C language but the code isn't executed inside the smartphones. It is send to the server via internet and the servers return the results.
So old pocket computers of late 80's have unique properties.
Of course very small netbooks or the raspberry Pi can be programmed directly but are not very very small like smartphones.
You are wrong on several points. Perhaps you ought to do some more research about old computers and modern smartphones.
A Nother why don't write what is wrong?
Ebay has these antiqueZ88, for $100 or more. LOL!Just bought an ASUS TRANSFORMER T100TA 10.1" Touchscreen 2 in 1 64GB SSD Windows 10 tablet for $90, used/like new!So, for less $$$$ than Z88 antique !
That's to be expected, one is relatively new and common, the other is a hard to find retro classic. In a few years, the T100TA will probably be worth a lot more.
Dave, do you really live on an Island?
It would probably have a hard enough time just trying to run ms-dos!
I don't even think it's possible to run Linux on a z80.
Looks like it's got all the Uncle Clive trademarks, Smart, but cheap and shoddy... well maybe shoddy is a little unfair but I still remember all the rituals that you'd develop when trying to get a Speccy to load from tape. They weren't hideously reliable machines.
I bet those 128k RAM packs cost a bomb back in the day.
Dave, why you still reffering to Z88 CPU? There is no such CPU!