Saturday, March 04, 2023

The Wheels On The Bus Go...

 ..."Cannot try Winchester disks as IEEE bus is not active. Is the IEEE cable connected?"

Stop mocking me...

Dangnabit. After getting so far with the Cifer, I hit a brick wall. The hard disk on this computer is connected via the IEEE-488 bus that permeates the entire unit. Basically, there is a 488 connection from the desktop processor board which then links out to the graphics board, the MC68000 processor board and the SASI controller board. SASI is basically the first version of SCSI. See the most excellent video from RetroBytes for more SCSI history.

Desktop processor board, for processing err...desktops?

The Cifer SASI controller board is really more of an interpreter, since there is a 'real' hard disk controller connected the drive, a Xebec 1410. This then feeds the SASI (see later on) data into the SASI interpreter which then translates it into IEEE-488 data and fires it across the bus.

At least, that's the theory.

Don't get SASI with me young man!

A week or so ago I decided to look more closely at the hard disks. I was disappointed that they didn't seem to work, although it should not be unexpected given their age. I had decided to follow the example of Adrian of Adrian's Digital Basement to see if the head stepper motors could be coaxed into life (see here and here).

To do this, I plugged the drive into power and switched it on. Just before the drive would lock the head stepper motor I quickly turned the knurled knob (no sniggering at the back) and watched to see the result. Interestingly, on both drives I had the same result. A fairly rapid resetting of the head back to a home position. But also, once I had done it a couple of times, it became obvious that the drive heads would, when left alone, do a very small but perceptible 'shuffle' once the drive reached full speed. And it did the same on both.

Incidentally, as part of my fiddling with the units I stripped them down a bit to get all the dust and cobwebs out (foreshadowing). 

The bottom of the drive spindle with brake.

The Rodime drive board. Lovely.

The other en....ARGHAGAH!!!

As a grown man, I should not be able to make such a high pitched squeal of fright. The vacuum cleaner was summoned..

Anyway, after this slight detour, I went back to the unit and decided to do some chip swapping to see if I could prompt the bus to start working. It did not go well. There are several Z80 processors scattered around this machine so I thought I'd start there with my swapping. Removing chips is normally no big deal. Except when it isn't.

There's still 39 legs. What's the problem?

Unexpected socket replacement in 
the workshop area...

Fortunately, it was fairly easy to repair by soldering an offcut of a component leg to the remaining portion of the original leg that was left. With a new socket installed I put everything back together (or had I?) and tried again.

One step forward...

But then I realised I hadn't plugged the power back into the SASI board. Which I then rectified and plugged power in.

...Two steps back.


(To be continued....)

Sunday, February 05, 2023

My Keyboard is Missing a Key - There's no Escape

So the Cifer keyboard is just not working. Pressing any keys gives nothing on the screen at all and, despite hammering the keys, it's dead, Jim.

Keyboard. And computer...

Stripping it down reveals something that every retro computer nerd... er... enthusiast dreads to see. A keyboard that relies on conductive pads on sponge pads. They. Are. Shit. I've mentioned these in one of the previous blogs on this machine but I'll say it again. This type of keyboard switch is cheap and almost certainly destined to fail as the sponge always breaks down resulting in the keys just not working.

Urgh! Capacitive pads. Bleurgh!

Anyway, after stripping it down I started to probe around the PCB inside. There's no membrane inside, rather there are chunky soldered pads that the conductive ends of the key stalks press down on to. Inspecting the board reveals no obvious issues or corrosion which was actually a bit of a surprise. The few electrolytic caps still look in good condition with no leaks.

It's a PCB alright.

After a bit of probing I found a rather cool signal that changed when the key was pressed. What I did was remove one of the key stalks from the keyboard and basically stab at the soldered pads on the board. Unfortunately, I didn't note which chip I was on (or which pin) but I know it was to the left of the board. 

Despite my inability to record what chip I was poking at, this was still some good intelligence as it suggested that the fault would be towards the right of the board where I couldn't find any similar signals. Then, as I was handling the PCB to change probing positions, the Cifer beeped (never heard it do that and it made me jump!) and some garbage characters appeared on the screen. This was excellent news as it meant that the keyboard was still alive for something! 

Garbage on screen thanks to a good poke.

After a comprehensive round of humanistic digital probing (I kept poking it with my finger), I worked out that if I touched the pins of IC6 or IC7 then garbage would get sent through the keyboard to the Cifer. I managed to see this on the oscilloscope which displayed the serial traffic but only when the probe (my finger) was in contact with the pins. This meant I must have been coupling something together to allow the serial circuit to fire so the main suspects were IC6 and IC7. They are a CD4011 and CD4075. 

New chips were ordered and, after a bit of wrestling, IC7 was replaced. No change.

IC6 was replaced. Hmmm. A bit of a change. Touching the pins of IC6 and IC7 no longer prompted the garbage but touching IC5 did.

So, given that I had received 10 CD4011s I thought I would also replace IC5 anyway. And.... it worked. I poked at a pad with the keystalk and a letter appeared! Yes!

You have no idea how long it took to type that...
(with a single keystalk on a bare pcb)

Three chips replaced. I was close, it was IC5 at fault!

A working keyboard should mean that I can now see if the rest of the machine is working. One thing I had noticed was that the display seemed to be shifted too far to the left. This meant that anything on the left of the screen was slightly cut off. A small issue but rather annoying.

Typing loads - but it's shifted to the left
(the correct text had an extra space at the start!)

No plastic tools available. Fortunately, there's only 12000v
behind the brown plate. So that's nice.

There are quite a few controls on the top of the CRT. These are basically various variable resistors to allow for tweaking to the picture. Normally, it's recommended that a plastic tool is used to avoid any distortion to the picture caused by a metal screwdriver and also to avoid getting your face burned off (12000v in there chaps). I don't have plastic tools so I very gingerly tweaked the 'PHASE' variable bit with a screwdriver. Don't judge me.

Picture corrected.

And that solved that issue. Today is going great. :)

At this point I should probably say that I had carefully read the manual and was fully aware of how to access the floppy drive to test. In reality I just start pressing keys until I found that 'Shift' and 'Disc' asked me to put a disk in the drive and press the RETURN key. :)  A quick search through the boxes of disks revealed one with CPM on it and it was duly inserted and the correct key pressed.

And CPM booted. And just worked! Absolutely AWESOME! I am on a ROLL! Let's try the hard disks...

Nope. Nothing. Certainly nothing out of the worlds noisiest hard disk. There is a spare unit which I also tried and this is much quieter and gets to the 'READY' state much quicker. But it's still not working, although there is an error message now about the IEEE bus not being active. Interesting.... 

CP/M! Ah, computing as it should be.

A zBASIC program in honour of Usagi Electric
But I made an error when I copied the error...

Hmmm. No IEEE bus..

So, it may be that the cable is either loose, disconnected or just making a bad connection at either end. It's the next thing to check and, if I'm lucky, may be the last fix needed to get the Cifer up and running properly. But that's for next time.

Today was a good day. :)

Oh, and in case you were wondering, EVERY key works. Who knew?

Tuesday, January 17, 2023

I've got the POWER to fix.

Ah, the joy of retro computers. Plug it in. Turn it on. Wait an unspecified time (anywhere from a couple of seconds to several hours) and then...


Release the magic smoke.

The culprit(s) for this behaviour are capacitors. More specifically, they are generally X2 capacitors made by a company called RIFA and which are made of paper and plastic. X2 capacitors sit across mains voltage. As they age, they start to crack, and once cracked, moisture can get in, especially if the equipment is stored somewhere very slightly damp. After a good few years, any attempt to switch the equipment on sets mains voltage across a broken capacitor, filled with damp paper. The results are predictable..


So, in the Cifer 1887 there is a power supply and this has five RIFA caps in it. The largest went bang the last time it was switched on. 

And then it was given to me. :)

Here are the five miscreants:

Begone, foul rectangles of destruction

And here are their replacements:

With miscreants for scale.
Note the smaller size particularly the 0.1uf X2 (blue dudes).

After a brief bout of soldering the caps were all installed and the power supply put back together along with the many screws holding everything in.

Time for the big switch on...

Well, it works. Sort of. The CRT is at least operational and was initially nice and bright although it did become dim quick quickly. Fortunately this machine has the added benefit of a composite out port on the back. It's a BNC rather than Phono but I have a couple of adaptors lying around that will help out nicely.

And this is the result on my re-purposed LCD screen:

Um. Indeed.

After the switch on I realised that there was something missing. There was no sound or noise from the hard disk. I would have assumed that it would spin up at least even if it couldn't boot. Then I noticed the light on the front flashing in a regular pattern. The drive must be telling me something. The pattern was a long flash, short flash, long flash, short flash, pause, repeat.

The HDD is a Rodime 200 series full height drive and, as luck would have it, there are a couple of sources of information on the drive on the interwebs. If I'd looked, I would also have seen that the drive error codes are in the back of the maintenance manual. READ. THE. FLIPPIN'. MANUAL. 

The code the drive was giving me was code 10 which means 'No INDEX' which is not a surprise given that it wasn't spinning. Although I was surprised it wasn't actually code 11 which means 'Motor not up to speed'...

After wrestling it out of the case (this thing must weigh three or four kilos) I had a closer look at the drive which revealed that under the circuit board there was what looked like a flywheel which would be attached to the hard disk spindle. I gently poked at it with the end of a cotton bud but it wouldn't move. A slightly firmer push and it slowly started to rotate. Hmmm.

So I put it back in and switched everything back on. The video below is the second attempt as the first failed with the drive partially spinning up and then shutting down - and then it actually did report error code 11. 

After a few seconds you can see that I slightly back away from the thing. It is the most terrifying noise I've ever heard any computer equipment make, but the drive dutifully put on its 'Drive Ready' LED, prompting me to say a bad word in complete disbelieve. But even if by some miracle the howling banshee HD still works, it's no good if the computer itself isn't working.

So, to re-cap (pardon the pun), the hard disk is now spinning, albeit a little(!) noisy. The main unit is outputting video but it's garbage. The CRT seems to work but starts bright and then gets dimmer over the course of a few minutes until it almost looks off. The voltages from the power supply appear OK though (although 12v is about 11.5v). There's still lots to do so lets get that bottom off.

Wow. There's a lot to unpack under here. Literally... With the unit on its side and the bottom panel removed there are three distinct boards, with more hiding underneath.

The bottom board is the hard disk controller board. Other than being able to see the hard disk cables and noting it's two boards sandwiched together I have not really looked at that yet.

House of cards.
(See what I did there?)

The right hand board is the first one I actually unhooked from its 'moorings'. There are white plastic clips holding the boards in at one end with fairly standard looking plastic PC board stand-offs at the other. Once I got these disconnected I could see what was on the other side. And, oh my! This is a 68000 processor board. This means that this unit is/was kitted out with UNIX! NICE. And it has 256kb of DRAM.

68000 Processor and a BUNCH of RAM.
**Happy Dance**

Next up, the board on the left. This is (apparently) the 'graphics' board which provides Tektronix 4010 compatibility. Nope. I have no idea what that means either. But it does have another 64kb of DRAM.

Graphics Board. 

Moving on, the next board is a big one and covers the same area as the previous two boards combined. This is the main processor board and has lots of RAM with a Z80A and Z80 support chips. I can see why chaps like Clive Sinclair and Chris Curry where keen on the idea of ULAs. All the logic on these boards is discrete and puts me in mind of the main board of an original Commodore PET or the BBC micro. So. Many. Chips. Including what looks like yet another bunch of RAM, again 256kb.

Processor board. That's a lot of chips.

Finally, we get to the last board which is the VDU board. This is responsible for generating the text on screen as well as handling serial and parallel comms for printers etc. It has seven EEPROMS presumably for it's ROM, five chips of static RAM for the display and another 64kb of DRAM for er... stuff. Well, if all else fails and this machine can't be repaired I'll have a shed load of spare 4164 RAM. :)

VDU Board

Now the question is, what is causing the garbage on the screen?

First things first, I turned the machine on and checked the video output. Then I removed a card and tried again, starting with the 68000 card. I got all the way to the VDU card and the output was exactly the same.

This means the fault MUST be on the VDU board.

So I tried some basic chip swapping. There are three Z80A CPUs scattered across the various boards so I tried a quick Z80 swap. No change. CTC swap. No change. Z80 PIO swap. No change.

Then I tried moving the static RAM chips around to see if the output would be different as the five chips do different parts of the VDU output. No change.

After a bit of head scratching I went back to the board layout and schematic in the maintenance manual to see what else might be happening. And wouldn't you know it, I'd forgotten about the DRAM. Out came my heath-robinson DRAM tester and within half an hour I'd found a dodgy 4164 RAM chip. 

It is an ex-DRAM chip.
Leg is bent so I don't put it back in!!

A quick hunt through the spares box revealed a suitable replacement which was duly inserted into the convenient socket. Every chip on these boards is socketed. No wonder they cost £5000 brand new in 1983..

But did that change anything?


In a fit of optimism I put all the cards back and also put the hard disk in too, just to see if it would boot UNIX or do anything other than have a flashing cursor.

Sitting, chillin' looking cool.

Sadly, it did not boot. But then I can't get the keyboard to do anything either. There are three possibilities:

1) The keyboard is broken in some way preventing it interacting with the machine.
2) The computer is 'locked up' due to another fault.
3) I'm doing something wrong because I'm an idiot.

One thing at a time. 

Saturday, January 07, 2023

Insert funny title here - Cifer Series 1 model 1887G.

I couldn't think of a funny title. Never mind.

My most amazing colleague has been at it again and has given me a small consignment of retro computer goodies.

Oooh! Nice! ...What is it?

This time it's a small black computer with integrated CRT, floppy drive and 'Winchester' disk. That should give you an idea of the era this thing comes from. Yes, it's the early 1980s (actually a bit later for this particular machine).

It's a Cifer Series 1 model 1887G. Nice. It runs CP/M, can act as a slightly less 'dumb' terminal or can (allegedly) run an early version of UNIX although I suspect it would need the additional MC68000 processor card for that. 

UNIX you say? Really?
I look forward to seeing if that's true!

It's a manual. For maintenance.
(I have Technical one too.)

Lots of brochures and price info. Cool.

Other than the free spiders, there was a lot of documentation and many discs provided with the unit, but it may be a while before we get to them. The unit was reported as having booted the last time it was switched on but after a few minutes there was a 'POP' and wisps of magic smoke emerged from the case. Anyone who knows anything about retro machines will immediately suspect that there are RIFA capacitors that have gone bad somewhere inside in the power supply section.

Rear view. It has composite output!

Power supply box at the back.

Unit tested August 1987.

Floppy drive on the left.
Winchester on the right.

And so it came to pass that this suspicion was correct.. There are five RIFA caps in the power supply and four are badly cracked and ready to pop. The fifth, and largest, is the culprit for the previous popping event. Fortunately, these caps are readily available and so an order will be going in to whichever online shop charges the lowest small order handling fee (gah!). 

Power supply removed and opened.

"Well, there's ya problem!"

Culprits removed.

The rest of the machine is in fairly good condition. The keyboard uses the dreaded 'foil and foam' type contact with the keycap return being a simple spring. Fortunately, the foam has NOT degraded at all. Whatever material they used I'm glad they did as replacing those pads would have been a nightmare (see HERE and HERE for YouTube videos of Adrian's Digital Basement and the 8-Bit Guy respectively doing exactly that). 

Not microswitches. But the foam is still
intact. Yay!

And so until I receive the caps there's not much else I can do here. It looks awesome and I'm hopeful that the CRT with its flyback and the Winchester disk - all 10Mb of it - will still work once the power supply is back up and running. 

We shall see.

Friday, December 09, 2022

I've got a BIGGER one!

In days of yore, computer manufacturers would include tons of useful information on the products you bought. Need a schematic? It's in the back of the manual. Have a problem? Comprehensive troubleshooting in the manual too etc etc. One such company was HP. Their electronic equipment was legendary (not just computers) for the build quality and information provided to the user. It's almost as if they understood that you owned a unit they had made and you had a right to understand, use and even repair it as you saw fit. What a novel concept these days (looking at you Apple).

Anyway, they also made some fairly hefty high-end UNIX workstations. And guess what arrived in the garage in the last couple of weeks? Yep. An HP 9000 workstation, model B132L. Alongside the main unit and the absolute UNIT of a monitor (more on that in a minute) came HPUX on CD with many updates - also on CD - along with books and manuals. The only thing missing is a PS2 mouse. 

Ten grands word of 'puter.

It's an old fashioned, proper HP.

First things first. The monitor for this is FECKIN' HUGE and FECKIN' HEAVY. Seriously, this thing must weigh 40kg. I can just about lift it up off the ground and get it on the desk. Put it this way, the back end of my car was rather low on the drive back from pick-up... It's got three BNCs on the back for the video signal, with what looks like component video (it's actually RGB with sync on green). Resolution seems to be 1280 x 1024 which is pretty good for 1996. Oh, and did I mention it's 20 inches? 20 FECKIN INCHES! It's so heavy, it bends spacetime in the vicinity.

Is it the biggest monitor in the world? No.
Is it the heaviest? Probably.

But does it work? Well, the monitor does, yes. The first time I turned it on it scared the cheeses out of me because it did a de-gauss - as CRTs are wont to do - which makes a bloody loud 'BOING' sound. Subsequent turnings on were less exciting. It is a fixed frequency and resolution though so unless what its connected to is spewing out 1280 x 1024 at 72hz, there's not going to be much displaying going on.

Monitor boings and works.

The actual workstation itself is also built like a tank. These things were expensive back in the day though, starting at around $10,000. That's around a truckload of cash today. And that was the starting price.

So what would you have got for all that dosh, in 1996? Well, not as much as you'd think. First up, you get the HPUX OS which is a variation of UNIX. Anyone who has used Linux will be fairly familiar with some of the operation of UNIX although they are not exactly the same (more on that later). From a hardware perspective the unit I have has a PA-RISC processor running at 132Mhz. There's a whole 64Mb of RAM too, to go along with the IBM 2Gb SCSI (HVD SCSI2) hard disk.

So lets get that top off.

The case slides off like a very heavy
metal glove.

And we're in...

Starting at the front right we have a SCSI CD-ROM drive (caddy variety) which needs some mounting brackets (3D printer might come in handy here). I actually have a SCSI CD-ROM from an Amiga setup somewhere which I might put in here as I really don't like the caddies. 

Behind the CD-ROM there is the hard disk. Not much to say about that. It's a spinning rust drive.

Then heading over to the left side there is an additional graphics card. This card is what I've actually plugged the monitor into since the built in DVI connector doesn't work with a VGA-DVI adaptor (which is a REALLY tight fit). There is some signal but it's distorted and flickery. It may be that a standard VGA monitor might work properly. If I can find my missing VGA cable I could try and prove this...

In the middle is the CPU and RAM. Note the tiny heatsink. But also note the fairly hefty pair of fans at the front too.

At this point it occurred to me that there may be a battery somewhere in here. And I was right:

Ah. There it is. 


It actually looks OK so I decided to leave it where it is for now. I will try and get a replacement at some point in the future.

After putting it all back together it was time to see if it would boot. After several days of training and a pep-talk from a nearby weightlifter, I managed to get the monitor up onto the bench (the photo above was taken after my epic lift) and get it all plugged in and ready to go.

Did it boot? No.

Why won't you boot?

So, I took the case off and found out that SCSI drives don't work wirelessly. 

You mean I have to plug it in? Sooo 90's..

Case back on. Pep talk. Work out. Monitor lifted. Try again...

Did it boot? Yes. Sort of...

It started HP-UX but then declared that there were lots of file errors that needed to be corrected. It corrected them without me confirming or denying permission and then re-booted. And got stuck in a boot loop. 

Basically, I think that the files that had errors were actually related to the GUI. So it would start up and attempt to start the GUI and fail, reboot and try again ad infinitum..

At least it starts to boot.

Console login but no GUI :(

Fortunately I have the CDs so I can re-install the OS from scratch. I did give this an attempt but I ran out of time. The disks had around 650 packages to install and it took about eight minutes to install three. If that was an average time for three packages it would take a few hours to get this installed so I need to wait for a lull in proceedings and a spare half day or so to do it.

I may be some time...

Did I mention the monitor is FECKIN heavy?