EEVblog #955 - World's First Portable Computer Teardown

[EEVblog]

What's inside the world's first portable microcomputer?
The Osborne 1 from Osborne Computer Corporation torn down.
An Adam Osborne and Lee Felsenstein design.
ROM Dumps:
http://www.eevblog.com/files/Osborne1-ROM-RevE-1-44.BIN
http://www.eevblog.com/files/Osborne1-CharROM-RevA-7A3007-00.BIN

[TheRevva]

I'll take a dig around in my old junk piles as I'm pretty sure I have a set of CP/M 80 boot floppies in there somewhere
(For that matter, if the ROM BIOS was written to the specs, then we can generate new boot floppies - Gary Kildall would possibly be unimpressed though)

[amspire]

My first portable computer was a Bondwell that was basically a big improvement to the Osborne at a much cheaper price.



Really had fun on this. There were a few instant compilers available for cp/m  - I had Borland Pascal and a C compiler from another company that were really amazing. These are very slow computers, but these compilers would compile and run instantly. At university, I had to do computer programming on computer card decks, and pick up the results the next morning. To be able to compile and run genuine C instantly on a home computer was mind-blowing.

The Bondwell came out in 1984 - so why would anyone be using a CP/M computer in 1984?

I was using PC compatibles at work (NEC computers as their monitors killed anything IBM produced), but the original PC price in Australia was incredible. When the IBM pcs were available with the 10MByte hard drive (yes Mb , not GBytes), you could easily spend $10,000 at Computerland. This was about the same price as a new Mazda 323 car at the time.

The Bondwell CP/M portable was, from memory, sub $1000 and there was a lot of readily available and cheap software. My CP/M C compiler was $49 which was a bargain as any professional C Compiler usually started at hundreds of dollars into the thousands.

The first PC I brought was shared with my brother in about 1986/7. It was a $2000 pc clone (a 80286 I think) but at the time the RAM prices were through the roof. To get the 4MByte expansion memory card (which you did need) cost us $4000 extra.

Before the Bondwell, we did have a Australian designed Microbee (about $400 I think), but it used an audio input/output to a cassette tape for storage and needed a monitor or tv (not cheap then). A nice build but the moment I got the Bondwell, I never touched the Microbee again.

[Silveruser]

 >:DBrings back memories. I bought one of the first batch shipped to Canada! Yes I did also get the external 12in monitor to go with it. I also had it upgraded a year or so later for double sided drives and 80x24 display. That second board may have been the display upgrade. I remember a huge rats nest of wires after the upgrades. I believe I might still have disks and manuals somewhere, sadly the computer made the trip to the dumpster at my last move. It had long since failed working and was replaced by new Panisonic luggable with MSDos and a plasma display.  If I recall the service manual had a lot of info on some of the design problems they faced in the day. Worth noting it had 128k of ram, twice what the Z80 supported, they used bank switching. I believe to load most of OS in one bank and programs in the other. BTW the keyboard can be used to prop up the main case making the screen at little easier to read - might be the reason it is so thick.

George

[GumUlf]

At around 12 min into the video Dave uses two multimeters as feet for the Osborn 1. First I thought it was the EEVBlog BM235, but at around 12:30 you can see one of them in the lower right corner. It is not a BM235, but it almost looks as if it has the EEVBlog logo at the top. Is this a new EEVBlog multimeter, or is it an other model with a blue case and something that looks like it might read "...log" at the top of it? What multimeter could it be?

[Brumby]

At around 12 min into the video Dave uses two multimeters as feet for the Osborn 1. First I thought it was the EEVBlog BM235, but at around 12:30 you can see one of them in the lower right corner. It is not a BM235, but it almost looks as if it has the EEVBlog logo at the top. Is this a new EEVBlog multimeter, or is it an other model with a blue case and something that looks like it might read "...log" at the top of it? What multimeter could it be?

Become a 'Supporter' and you will know.

.... but there has been an indication that we might see something more public:

Early in the new year ...

[amspire]

Where did you get a Bondwell 12 in Australia? Dick Smith was only selling the model 14 and it was $2495 IIRC. Yeah not many people were buying CP/M machines in 1984.

I wish I'd kept my BW14.

Ours must have been a Bondwell 14 - definitely had the 128k of ram and the 360K drives.

I cannot remember were it came from - not Dick Smith. I have a suspicion it was purchased in the US.

Along the way, it disappeared  - probably in a move. If it ever turns up again, I probably still have many of the disks for it.

[codfish28]

The later revisions of the Osborne 1 were available with a 80 column display and double Density 182k floppy drives. I have one of the later Ozzy ones with both of those features And just like most osbornes it still works 100%.
https://en.wikipedia.org/wiki/Osborne_1
http://oldcomputers.net/osborne-1.html

[bktemp]

After seeing the (already cracked) RIFA caps in the power supply, I totally expected to hear a large bang when Dave powered it up.

Dave, before turing it on again, replace the X2 caps in the power supply!
Or have the highspeed camera running...

[kalleboo]

So from codfish28's second link, it looks like that daughterboard with the links everywhere onto the motherboard was a later (1983) display upgrade for 80 lines (which is also why the RCA jack doesn't have a label on the front - it was added in after the fact)

[Fungus]

It's often been said that you can never have too many multimeters, but... when you start using them as door stops, I dunno.

[Fungus]

Looks like they designed the main board without video (RS232 terminal?) then figured out a way to get video without modifying that.

The CPU-on-other-board thing is bizarre. Or genius, I'm not sure which.

[Fungus]

A little research, ie. Wikipedia, shows that Osborne offered a "Screen Pac" 80 column upgrade. Interestingly developed by a couple of Aussies.

Maybe the horrible hack was just Osbourne planning ahead.

[lol36]

There is a guide to get yourself a "new" boot floppy disk: http://www.classic-computers.org.nz/blog/2011-12-23-disk-from-images-cpm.htm.

I guess you can use DOSbox (or any other alternative) to get around the 'windowsless environment' problem.

BTW, a floppy drive on eBay is a few dollars at most (I haven't searched too hard for a cheaper price)

[rollatorwieltje]

Is that really the reset button under the delete button? That's just evil

The keyboard layouts of these early machines are always interesting. We had a Philips P2000C in the museum at university, it also had some funky keys. Most notably the "jump" key that worked like home/end/pgup/pgdown depending on the arrow key you pressed after it, and the numeric pad having separate buttons for inserting 00 and 000. It also had both shift lock and caps lock, for those who were used to the behavior of a typewriter I guess.

[Kleinstein]

Back in that days there where printers with GPIB / IEEE488 interface available. I remember we had one in school. Comodore PET also used IEEE488 for periphery.

[shabaz]

Fantastic video, I never thought I'd ever get to see the insides of the Osbourne computer in such detail.
I think the comments by @Wilfred makes sense, maybe that board is an add-on afterwards, to provide some higher res external video output. The RCA connector did look like an add-on, because it wasn't labelled on the front panel.
When the board is plugged on, the Z80 and a couple of other parts are unplugged and then plugged onto the add-on board.

[VK3DRB]

It is not the worlds first portable computer. Not by a long shot.

Released in 1975...
https://en.wikipedia.org/wiki/IBM_5100

(I actually had one of these in my home in 1980.)

[Brumby]

Talk about flashback....

CP/M, DBase II, Wordstar, dual floppies ... and writing application software.  Getting performance on a 3 file merge on a machine with only 2 floppy drives back then...  Fun and games.

Nice teardown.  There really was a lot of wasted space in there, but I suppose the industry was only getting into portability as the selling point.  Compactness came later.

[imidis]

It's often been said that you can never have too many multimeters, but... when you start using them as door stops, I dunno.

LOL Great catch!

[niekvs]

At around 12 min into the video Dave uses two multimeters as feet for the Osborn 1. First I thought it was the EEVBlog BM235, but at around 12:30 you can see one of them in the lower right corner. It is not a BM235, but it almost looks as if it has the EEVBlog logo at the top. Is this a new EEVBlog multimeter, or is it an other model with a blue case and something that looks like it might read "...log" at the top of it? What multimeter could it be?

Become a 'Supporter' and you will know.

.... but there has been an indication that we might see something more public:

Early in the new year ...

Hmm... Let's hope, for Dave, he won't get caught by the Osborne Effect and fail to sell any of the BM235's now

[djos]

Hmm... Let's hope, for Dave, he won't get caught by the Osborne Effect and fail to sell any of the BM235's now

Lol, it has a much more advanced featureset than the BM235 and I doubt it will competing in the sub $200 category.

[jonovid]

anyone still got a commodore 64 for Dave ?. also I use Test Equipment as stands too.    whatever is just laying around the bench.   

[djos]

anyone still got a commodore 64 for Dave ?. 

I like mine too much to send in. 

[jonovid]

sadly I sold my much loved C 64    as upgraded to a new IBM, so we could get into the new fad, at the time, called the World Wide Web. 

[djos]

sadly I sold my much loved C 64    as upgraded to a new IBM, so we could get into the new fad, at the time, called the World Wide Web. 

I was lucky, I got given this one by a family friend who found it in their garage.

Ps Dave would likely be bored silly by a c64 tear-down as there's bugger all in them (heatsinks added by me).

[Towger]

Hmm... Let's hope, for Dave, he won't get caught by the Osborne Effect and fail to sell any of the BM235's now

Problem is he has already missed the Christmas market and those of us with Kids will he broke for months after it next year. [emoji53]

I C64 teardown would be interested if he could get all the revisions.  It is a good example of electronic miniaturisation over the years.

[djos]

I C64 teardown would be interested if he could get all the revisions.  It is a good example of electronic miniaturisation over the years.

Not really, all revisions have the same chips, 2x VIA (keyboard and joysticks), SID for audio synth, VICII for video, 6510 CPU, ram chips, a Rom chip a PLA and not that much else.

Here's the '85 and '92 service manuals if you are interested.

https://www.dropbox.com/s/2ew80uo58qoymr0/C64_Service_Manual_314001-02_%281985_Feb%29.pdf?dl=0

https://www.dropbox.com/s/xgdpis2nuaya0lx/C64-C64C_Service_Manual_314001-03_%281992_Mar%29.pdf?dl=0

[Fungus]

I C64 teardown would be interested if he could get all the revisions.  It is a good example of electronic miniaturisation over the years.

Nah, I don't think they changed much.

(they wouldn't dare - almost every C64 game relied on hardware bugs and undocumented 'features' to work  )

[djos]

Nah, I don't think they changed much.

(they wouldn't dare - almost every C64 game relied on hardware bugs and undocumented 'features' to work  )

Exactly, when they released a "bug fixed" SID chip in later C models, they broke a bunch of games that where using the bugs to do things the SID wasn't supposed to be capable of.

[Moshly]

Actually there are 4 cost reduced versions of the C64

Original board
Integrated TTL logic into custom PLL Clock chip.
Changed DRAMs to 2x 64k by 4 (replaced 8x 64k by 1)
C64C, integrated more glue logic into the PLA, Changed to HMOS chips from NMOS (Smaller PCB)
C64C, moved the color SRAM chip into the PLA

I think sending Dave more obscure stuff is more interesting, Commodore, Atari & Apple stuff is too common.

How about some 80's Dick smith offerings like ->
Dick Smith VZ 200 / 300, Dick Smith CAT (Apple 2 clone) or Dick Smith Wizzard.

[djos]

Actually there are 4 cost reduced versions of the C64

Original board
Integrated TTL logic into custom PLL Clock chip.
Changed DRAMs to 2x 64k by 4 (replaced 8x 64k by 1)
C64C, integrated more glue logic into the PLA, Changed to HMOS chips from NMOS (Smaller PCB)
C64C, moved the color SRAM chip into the PLA

I think sending Dave more obscure stuff is more interesting, Commodore, Atari & Apple stuff is too common.

How about some 80's Dick smith offerings like ->
Dick Smith VZ 200 / 300, Dick Smith CAT (Apple 2 clone) or Dick Smith Wizzard.

Doesn't really count as "miniaturization" tho does it.

The Commodore 64 DTV, now that's miniaturization!

https://en.m.wikipedia.org/wiki/C64_Direct-to-TV

[Towger]

The Commodore 64 DTV, now that's miniaturization!

Jerry's pension fund is the leftover C64 asic dies.

[djos]

The Commodore 64 DTV, now that's miniaturization!

Jerry's pension fund is the leftover C64 asic dies.

[rbm]

It is not the worlds first portable computer. Not by a long shot.

Released in 1975...
https://en.wikipedia.org/wiki/IBM_5100

(I actually had one of these in my home in 1980.)

Man, I remember those things vividly!  I worked for IBM at the time those portable computers were introduced and I used those in the QA lab to setup production tests on manufactured equipment.  They were awesome machines but APL was a Bi*CH to learn.

Part way through the EEVblog video, Dave comments on the RAM chips on the Osborne being whatever came to hand.  I can believe that there weren't the same established supply chains that we have today available to a SMB like Osborne at that time (1982) so they had basically no choice but to use what little stock they could get a hold of.  It's so easy now a days to sit back and enjoy the convenience of ordering what-ever exotic part we may dream of found through Internet and get it supplied from unlimited stocks at global supply houses, but it wasn't always so, especially in the early days.

[cengland0]

When Dave tears down the floppy drive and you see a switch on the left, he claims that is to detect if a disk is in the drive.  I actually think that is to detect the write protect notch.  If the notch is there, you cannot write to the floppy.

[djos]

When Dave tears down the floppy drive and you see a switch on the left, he claims that is to detect if a disk is in the drive.  I actually think that is to detect the write protect notch.  If the notch is there, you cannot write to the floppy.

I checked my Commodore 1541 floppy drive and you are correct, it's the write protect detection switch.

Who recalls turning DSDD disks into Flippies with a notching tool so they could use both both sides?

[Brumby]

I can remember taking 8" floppies from an IBM mainframe (microcode updates) and punching a hole so they could be used on a TRS80 model II.  They worked - and could hold around 1 MB!!

[djos]

I can remember taking 8" floppies from an IBM mainframe (microcode updates) and punching a hole so they could be used on a TRS80 model II.  They worked - and could hold around 1 MB!!

Nice, 1MB was a ton of data back then, especially when you consider how much a 10MB HDD sold for back in the 80's!!! 

[meeko]

Who recalls turning DSDD disks into Flippies with a notching tool so they could use both both sides?

We didn't need any fancy-schmancy notching tool!  Just another disk to use as a template and a pair of scissors.  While walking 10 km, barefoot, through 3 m of snow, uphill (both ways) to and from school! 

The hard plastic of a 3.5" disk was a little tougher to get through to make DD disks into HD ones...  I did have a specific tool for that.  It fit over the disk the same way, but instead of having a punch, you screwed a cutter down that bored through the shell.

[djos]

Who recalls turning DSDD disks into Flippies with a notching tool so they could use both both sides?

We didn't need any fancy-schmancy notching tool!  Just another disk to use as a template and a pair of scissors.  While walking 10 km, barefoot, through 3 m of snow, uphill (both ways) to and from school! 

The hard plastic of a 3.5" disk was a little tougher to get through to make DD disks into HD ones...  I did have a specific tool for that.  It fit over the disk the same way, but instead of having a punch, you screwed a cutter down that bored through the shell.

Lol, yeah I used scissors for quite a long time, I just used another floppy as the template and a texta to mark the cut.

I had a specific tool for doing the 3.5" disks too, it was a really cheap and nasty soldering iron with a pointy round tip.