INSERT SYSTEM DISC... ORIC MICRODISC NEARLY THERE

OK, so i took the plunge earlier and opened her up - in for a penny, in for a pound and if I could find a loose cable/connector or check those DIP switches then it just might save Rich a job and about £10 in postage not to mention all the packing, wrapping and faffing etc (plus running the gauntlet of the P.O./couriers). So, here we go...

1st up - remove 4 screws underneath the microdisc and get the cover off...





2) Remove the disc controller board - 2 screws on the top towards the back.





3) Look to remove the disc drive cable and power connector below.



4) Note position of DIP switches and check that they are set to boot from an A drive (rather than set to B / slave setting) - I compared mine to notes made by: romualdl@oric-international.org
over at:
http://romualdl.oric.org/oric2pc/oric2pc.html

Unfortunately, his DIPs/drive manufacturer is different to mine but essentially, I feel that the switches are set correctly:



Note how both his and mine have their 2nd switch 2 set to "On - which should configure the drive as A:"

(mind, his drive - LEFT has 4 and then 6 DIP switches whereas mine - RIGHT - has 5 and then 7 switches).

5) Finally, I homed in on variable resistor RV1 - see lower central in this pic:



Guys, when I turned this fully clockwise, the Atmos refused to boot at all. I then tried the resistor in approx 3-4 positions gradually working back around to fully anti-clockwise and regardless of which disks I tried and how many times I ejected/tried side B/reset the microdisc at the back... all the Atmos came up with was the same old, old faithful...

INSERT SYSTEM DISC!

(ie. the title of the thread).

Rich, it's all boxed up here and good to go to you as I've exhausted the level of my checking / electronic's knowledge and doff my cap, hopefully, in your direction.

I was a bit hasty putting the microdisc back together and I've gone and neglected to refit the drive shielding and also 2 screws which ensure the 3" drive does nowhere on the lower plate - I've put them in the box and sellotaped them to the metal shielding within a parcel, positively bursting with:

1x Microdisc
1x PSU
1x Oric-1
2x Dragon goodies (all yours, mate, no good to me)
4x Oric 3" discs for testing purposes.

If you can get anywhere with getting the Microdisc to boot and/or fix the Oric-1 which has the old familiar random scrambled colour blocks/black bars here and there on booting, then please forget about the remainder of the Dragon deal and instead let me know what I owe you etc in parts/time and naturally I'll pay the return postage.

Many thanks once more to both Graham and Richie for all their input on this one - I really do think the Microdisc is "nearly there" and probably just needs that TLC/extra knowledge that Rich can give this kit...else, I'll willingly pay you, Graham, for your spare Gotek, mate, and take the plunge down the mod, mod, mod it route.

Cheers, chaps.

Will update you, Rich, when the courier label's complete and the parcel is all checked in/ready for uplift to you.

Thought for the day: Will Baz ever be euphORIC with his disc drive?!?

 

Hmm
Well I guess you have the same powers of finding things as I do!!!

Women appartently have eyes..

Well
I've two thought's
1: Well at least I'd put everything back together (hopefully correclty ..
2. It's a shame I'd not left something poorly connected, and thus you would have a working Micro drive

Andy
Can you let us know what it did used to do, I'e I know you mentioned it would format or write anything, and I presumed this was when it had overheated, wouldn't you mind letting us know what it did / didn't do and under what conditions i.e. hot cold just turned on etc.

I think I'm right in saying the Microdrive control board is working as I'm guessing it can read the onboard EPROM? hence the insert system disk.
I guess I should have had your Oric to go with it to test; as for me it's only ever done the same think, turn on Drive spins up. reset does the same etc etc.

I'm sorry It's not working and appears to be costing you additional postage as well. hope you kept the wrappings and I'd like to thank Richie for taking it on as well.

On a completly different track, does the name Claus Buchholtz mean anything to either of you, as I found him active on AA (and can see Matt has posted).
Some of the fanfold listing's I recently found has Claus's name on them, so have been PMing back and forth.

 

Hi Andy, shame it’s not an easy fix, I have found the service manual for your 3” drive and the dip switches are set correctly.
It could be the 3” drive that’s the problem... Like Graham says the logic board is working up to insert system disk.
It’s interesting that R15 & R16 are both supposed to be 3.9K but R15 is 3.3K on yours and there is a sheet that I shared with Graham that has modifications showing R15 @ 1K and R16 @ 3.3K with extra grounding on IC5 & IC6. Given it worked at one time I am tempted to leave them for now. I just hope one of the logic chips hasn’t given up the ghost. I have some spares from my second Cumana board but some like the FDC are a bit hard to get now. There is a supply from Bulgaria where they made the Pravetz but not all of them are. The logic chips are easy enough though a lot aren’t socketed which is a pain, that said I think the 3” drive might be the problem. Can you give a bit more background on the Microdisc Andy like Graham said and more on the overheating.
The Oric sounds like a RAM fault.
As far as Claus goes Graham the name rings a bell but I cannot put my finger on it.

 

Hi Guys
I think the resistor values are pretty close, so not sure the reason for the changes, I'll go and have a look.
I suspect that they may have earthed the inputs of spare gates to stop self oscillation, again something I'll go and check.
Claud Buchholtz was one of the original designers of memory upgrades on Atari's
The year before the 130XE was released, he had a published memory upgrade for the 800XL that used 32K bank switching, this was later updated to use 16K banks so to be compatiable with any software released for the 130XE.
tTe main use was for RAM disk's under dos, and Claus, has written updates to DOS 2.5 to use the extra memory.
Also the 'Quarter Meg XL' several companies copied the design RAMBO XL anyone; they however were not the only ones.
I only know him through the Michigan Atari users club, as local to the club was the C.H.A.O.S BBS that I spent money on calling via Modem, I became a pseudo member so to speak, Claus lived in the area and still does.
The same State that Tim lives in.. It’s a small world sometimes.
Let’s hope we have some luck with the 3" drive, but I'm also aware how they can play up. True of any Floppy drives but they did have a poorer name than some.
I'll say that the mechanism looked well made, but let’s see.

 

Hi,fellas.

Apols for the late, late, late show here but when the boiler and kettle both decided to play up today and pack in (low pressure and the element seem to have gone), it was an easy decision to go out to friends' Graeme and Sheila's for tea, after work, and their Thai green curry went down very well with rice, red wine, amaretto and some cheese biscuits etc so only just got in.

Sorry, fellas, I cannot contribute whatsoever on the name Claus Buchholtz other than I seem to recall Brenski mentioning him maybe once on Atari Sector as someone who had designed a memory upgrade so really I've had zero dealings there but the guy sounds like a very "switched on" fella in Atari circles.

As for the Microdisc... when it arrived from Paris about 10 years ago, it funnily enough always wanted me to insert a system disc then too - as I had no Oric DOS discs back then to stick in. That began my correspondence with Steve Marshall who was the only guy (from 4-5 I emailed) who actually replied and sent me a couple of bootable disks from the Oric user groups whom I asked for help from.

OK, I would say for about a month or so the drive would read disks and was fine. I then tried to write to and format disks and it wouldn't - I'd get various bad sector / format errors. Then a little later in time it began overheating... in other words my previous 15-20 minute sessions would now be down to 5-10 before it started playing up and refusing to read properly and I'd notice that the heat sink was seriously hot.

I then asked a mate, who is quite competent with electrics to have a look at the Oric's PSU. He more or less said that it was a pig of a construction and couldn't believe how it had been cobbled together or even ever worked properly (he'd serviced arcade machines in the 80s but thought that the Oric disc PSU design was seriously 70s archaic technology). Anyway, he faffed around with it a little and tried to make it less likely to overheat but my intermittent overheating continued when I tried to use my Microdisc.

I think I then sent it away to Thark who had a look up in Scotland and he tried cleaning the heads and giving it an overhaul but couldn't find much wrong with it (but like Graham, didn't own an Oric to test it on).

It's since been kicking around in my cupboards as when it came back from north of the border, it was still playing up - ie. you could read a disk but it wouldn;t write and generally was un-operable after a short while as it stopped working/overheated and I just switched it off for safety's sake.

It's been in that state for 4-5 years now so Graham's offer to completely overhaul the PSU and have a look inside the drive's mechanism was well worth the effort so thank you very much for that, Graham.

I had kept all your drive padding and wrapping, Graham (thanks again!) so the microdisc is well-packed and has gone off to Richie today and the postage wasn't too bad in the end considering it all came in at approx 6.5kgs incl the large box and packaging.

I think that's about it really... it's never worked 100% but worked better in the early weeks I had it and then seemed to deteriorate to the point now where it doesn't boot at all but let's see how you get on Richie, as you do have experience of things such as the Cumana Oric disk setup and have tinkered with both the Oric computer and floppy hardware/disk controllers before so you just never know.

GOOD LUCK and sincerely, thanks again, fellas.

 

Of all the floppy drive mechanisms the 3” seems the most prone to fail, even older 5.25” drives are still trucking like the 1050 Graham sold to me. The overheating after 20 minutes is a worry as I’m pretty sure it would be better documented on Defence Force or CEO if this was common so I think it is specific to your device. I never owned a Microdisk only a Cumana Interface so it will be a learning experience, but the Cumana has a lot of similarities.What caused the Heatsink to get so hot was the VR’s getting hot, how warm is it supposed to get I cannot say but we will give it a go. Graham has a much better skill set than me but I hope I can help out.

Graham,
What do you think of the mod reducing R15 to 1K and R16 to 3.3K? The article shows the oscilloscope traces to show the timing. This was a reply I had asking for the Microdisc service manual.

“In common, RV1 is used to adjust the falling edge of the MAP signal relative to F2's rising edge.
So the best rule is (as per Oric Service Manual p.15): MAP timing is important, MAP is a 250ns pulse, negative going with its leading edge occuring 80 to 100ns before the rising
edge of phase 2 (output from pin 39 of IC5).But for me this is bit 'theoretical' because everyone knows the (in)famous saw-tooth-like shape of the F2 signal.
Practically, by trial-and-error you should find such position of RV1 by which DOS works stable without freezes.”

 

Hi, Richie.

I would echo your sentiments regarding the longevity and reliability of 3" drives - I think they're easily the most prone to errors and breakdowns whereas, as you say, 5.25" mechanisms and 3.5" floppy disks (and drives) seem to go on forever like some indestructible brute force!

OK, drives themselves can be subject to all kinds of faults (especially if they've been roughly handled or dropped etc), but the irony for me is that of the three magnetic media types, you would think 3" disks should stand the test of time with them being in a tough outer shell and having their own plastic cases like a cassette, Meanwhile, 5.25" floppies are as flimsy as they come and are often stored in nothing more than a paper sleeve and even 3.5" disks (whilst having a tough outer shell) are often left "lying around" in drawers/on shelves etc etc and yet load 8-9 times out of 10 whereas 3" disks are shockingly unreliable...

It stinks.

Good luck, Richie - I do hope you have some success but no worries if you can't get it to boot, mate.
Thanks for trying and you just never know...

 

Hi Richie

Well it's clear others have looked into this in the past and come up with adjustments to improve things, it can't help to impliment this but suggest trying another drive mech as 1st port of call.

I'll have a look through the circuit diagrams myself. I'm guessing that the 'Phase 2' (F2) signal that is often the problem with multiple upgrades to Atari's; appears an issue here as well. I do have a pretty good solution to improving the quality of the Phase 2 signal. I post it here a bit later on.

The other issue not mentioned is the quality of RV1 itself, it may be worth updating this single component to one that’s in its own sealed environment, that's so the pulse width remains constant, so removing another possible issue.

I guess the first think to try is an alternative drive, as if the interface is working we have now narrowed it down to the drive, or even the control cable between the drive and the interface board, and it could of course be that simple, this has been disturbed both by me and I think Andy disconnected it as well.
Have a look in the larger block connector on the drive end, sometimes the pins 'hook' up and don't then press onto the card edge, just had this with the IBM as took apart cleaned, restored and the Drive didn't then work, if you look in the plug on the cable you'll see the strips that connect to the ribbon, one of these had got caught up within the housing and hadn't sprung back down, it was easy to spot, and used a needle to push to one side when it snapped back down to line up with the others. Can't say I'd had this before but worth checking.
If it proves to be the drive itself, I suspect we won't get too far, however you or I could strip this back down to check.
I have taken off the shielding, and removed the upper circuit board to properly clean the head; I do have High resolution photos of this, including the cables disconnected. I'll add that there is so little room you wouldn't be able to put these back incorrectly.

I'm not sure if you have an oscilloscope but it is possible to monitor the data send out of the drive to the interface on pin 30, this is a proper clean digital signal, after being processed on the drive itself, to allow it to pass through fairly long ribbon cables.

 

Narrowed it down to the 3” Drive yesterday Graham, my Gotek works like a charm so the logic board is fine. So need to have a look at the disk drive now.. talking to Andy about fitting a Gotek instead as a possible option if the drive is not fixable.
Amstrad CPC drives are different and are not drop in replacements.

If anyone has a Hitachi HFD305SE drive get in touch... apparently they were also used with Apple 2 computers so might be obtainable in the U.S.A

 

I've just had a search on the net not much about for sale missed one in France for 95euro inc shipping.
did see some pictures and although it stated it was for a
Hitachi HFD305SE, it was different to the drive Andy has fitted this could just be a revision difference.
Andy
I'd like to sort out with you, what you would like to do, firstly I do have a black GOTEK, basic and I also purchased the oled and rotary encoder to upgrade it.
Let me know if you interested in that happy to do the upgrade and send to You or Richie.
Alternative.
Fitting the Gotek in the original casing.
Due to the physical size of the drive being taller & believe narrower than a 3.5" (I didn't measure it) To make a clean install requires some work in making a suitiable face plate to match the drive opening, and then just fitting the guts of a gotek to purpose drilled and filed holes for display etc.
We (I) could also use the drive mechanism, remove some of it guts and use the face plate of the original drive to add display usb and encoder wheel. leaving the floppy drive slot.
I've added a few thumbnails of my BBC drive which I'll be moving into the 5.25" frame to mount in a dual housing with a real floppy drive. it's the one with the usb stick Oled & encoder.
the other I've got the bits to add, or custom fit to your requirements ..
Maybe it would work if all boxed up at richies end, sent to me, added Gotek, all sent to you ( that way I get to check it and experiance an Oric as well)

 

I have ordered a 3” Drive Gotek mounting bracket off eBay as the drive is the same size fascia as the CPC and Spectrum +3. I have the rotary encoder, oled screen and spare Gotek here already. So the plan is to see how that shapes up and in the meanwhile keep an eye out for a 3” Drive, in the meantime I’m working on the dead Oric-1 which so far has a working ULA,VIA so it doesn’t look like it had 9v via the expansion port.

 

Sounds like you have it all inhand their Richie,
And I was hoping for a play with and Oric as well
I'd guessed they had reproduced face plates for a gotek to fit, athough I've never seen a good finish apart from the cartridge port mount I purchased for my 1088XEL by

Professional 3D Printing Service
These are so good they look like injection mouldings.
by comparison I purchased a ROM port cover for a Beeb. It went in the bin nothing like the photo it showed on line.
I'm just glad that Andy will be able to make use of his Oric/Atmos collection.

 

If the Gotek faceplate looks naff when it arrives I’ll scrap it as the .stl files are saved on my laptop and I’ll get it printed myself ( I’ll have a look at that company you mentioned )
Oric’s are nice little machines if you get round the serial attribute display, and the sound was better than the Spectrum until the 128’s
If you want to play with an Oric I have a option for you, I built a Cumana disk Interface and all I get is the insert disk screen like Andy and it refuses to recognise any drive, be it a Gotek or 3.5” Drive. I have tested every logic chip more than once and burned new ROM’s. It is a bit of an odd setup as the original had a transformer in a metal case whereas mine is using a wall-wart PSU. The Oric power is connected to the Cumana and then you power the Cumana, which takes the -10V into a 7905 and feeds the Oric +9V. It’s a odd setup. My original in the 90’s was pre-built and just worked but this thing has me stumped. Do you want to have a look???

 

Hi Ritchie
Yes I'd be happy to, I've only just seen this post so don't know why I'd missed it, I'd just be looking for any new posts as I don't seem to get any alerts for same.
I've a Gotek or 5.25" so tick's that box, I take it the circuit diagrams are the same as we have posted on here but if you have anything else beside these that would be good, such as PCB lay out etc. My only concern would be the need to either buy or borrow an Oric, having just failed in my attempt to breath new life into Andy's Microdrive, but having no means of knowing or testing. I'd be foolish if I did the same again, having nothing for it to work with.
If I bought one I'd prefer the Atmos, purely on looks as I know the ROM can be changed to Atmos version.
Anyone ?

I wouldn't mind I had seen to Atmos's in France (link on here) I should have jumped in think they were only 50 Euro, I know there would be postage etc, and didn't know if it even worked, as I just spent money elsewhere.

In regard 'I.Materialise' I only used them as they already had the STL files as a project I believe, however the quality is superb,
I’ll take some photos for you to see.
I know little about 3D printing so how much difference does the STL file make to the finished product?

 

https://www.ebay.co.uk/itm/Oric-atm...328177?hash=item3da9e47ab1:g:2KcAAOSwGpxfMme7
£180 or Bid

https://www.ebay.co.uk/itm/Pravetz-...751559?hash=item2624c69607:g:XAkAAOSwcu9dWwVv
£230

https://www.ebay.co.uk/itm/ORIC-ATM...426733?hash=item5953d3016d:g:-4gAAOSwejBfL7UG
£270 or offer

https://www.ebay.co.uk/itm/Pravetz-...702678?hash=item2642286c56:g:Q2IAAOSwn1dfJulq
£290

https://www.ebay.co.uk/itm/RARE-VIN...190882?hash=item445bef61a2:g:8JkAAOSwddBe1jHB
£350

https://www.ebay.co.uk/itm/Pravetz-...640552?hash=item2a41dd2d68:g:JdkAAOSwjW9cL1ic
£501.78

https://www.ebay.co.uk/itm/RARE-RET...232354?hash=item5dac925f62:g:EwAAAOSwErlfDvEL
£500

I honestly think the £180 it far to much, I must be a tight fisted sod.
Give me a nice case and keyboard I'll make the rest !
I wouldn't mind some are clones !!

 

I was planning to send my Oric-1 down with it if you were up for it with the Cumana, I have schematics, parts lists and two PCB’s, one set up to run on 10v and power the Oric the other was going to be powered by a 5v psu separate from the Oric but I never went that far with it.
If you could get it into a case with a decent power system and get it to work and boot Sedoric then that would be great, plus you can play around with an Oric. The Atmos is essentially an Oric-1 with a much better keyboard and a v1.1 BASIC ROM.
You up for a challenge? You sound like you have better diagnostic tools than me so will be able to see what is going on.

 

The Oric-1 will need a SCART lead though I think, I’ll need to check the RF output as it was an Oric that had 9V through the board and every chip was dead so it’s a total rebuild and the only thing I didn’t replace is the PROM for the RF as I was using my SCART lead.
I do have a PROM Steve Marshall sent me so I can fit one if it’s toast as well.

 

The price of Oric’s is ridiculous right now but if you really want one the leboncoin.fr is a good hunting ground if you can persuade them to post to the U.K.

 

Hi Richie
Yep I'm up for the challenge, I'll see if I can find a service manual or at least something that help explain how the interface works. (Already have one for the Oric which has helped explain the expansion port control lines)
I can see that its split over two main sections
1. The interface towards the Oric or Atmos, that allows the Oric to see the additional ROM image, we know that part works.
2, The control part of the interface that drives the Floppy drive itself.
I guess there is a third part that then passes the data beween the Drive back and forth between the Drive and the computer.
I'll analyse the circuit diagrams, and see if these can be 'seen' as such as seperate blocks.
It's great that you have two interfaces I'd be happier with both, as I know I can check all the logic chips for operation and have many spares, The disk controller I have no spares for beside there maybe something common you never know.

 

Hi,
I’ll test the Oric’s RF first, sort that out and then box up the two PCB’s with the Oric-1, cables and 10v PSU I’m using. I have used a more powerful one and had the same result so I don’t think it’s underpowered. If you want to power the Oric on it’s own then it needs 9v 1A centre positive power supply. There are two FDC chips and two MB8877A controller chips. The Cumana board should work with a Microdisc ROM but the spare PCB has the Cumana EPROM.
I have a load of paperwork to go with the Cumana and some photos of the old case and transformer and send it down to you.Can you email me your address again please to make sure I get it right.

 

Hi Richie
I'll be o.k with just knocking up a scart lead, so its upto you in regard sorting out the RF, but I don't use this usually. I have PM'ed you all the details late last night or may have been this morning.

 

The Oric-1 is repaired now, needed new DRAM, I just replaced the lot as I had 8 4164’s to hand and there was more than one failed/failing, also replaced the 74ls257’s that controlled the DRAM access. Fixed a loose joint on the loudspeaker and now we just need to soak test the Oric, it seems like the CPU was okay after all and was the DRAM and the logic controlling that RAM that was the problem. Not sure what caused the damage to just damage the RAM but there you go.
Just need to sort out the Microdisc now....

 

Well done fella!
I've been having a look at the Oric circuit diagram, and it looks ripe to reproduce this with a few changes one use a single SRAM. and change the power supply circuitry, among a few ideas. the board is also small enough to buy without costing a fortune. something for the future maybe

 

I swapped the PROM with my new one from Steve Marshall but still couldn’t get a RF picture sadly, my TV’s don’t do well with old computers and RF input so I cannot tell if it’s working or not and now I think on it I don’t think I replaced the PAL crystal anyway as I was always going to use a RGB lead so a DIY SCART lead is probably better. With my current lead the power supply goes into the SCART lead to supply the current to switch a TV into RGB mode so that will need bearing in mind, otherwise it’s output is too dark to see anything same as the Amstrad CPC SCART leads you see on feeBay. I will get everything together and parcel it up next week, I spent this week working on this Oric-1.

 

I guess if you’re never going to use RF out then little point in getting it working. near all my Atari's have the Modulator removed, although they have a separate filter on the power line to them, they do add very slightly to the systems overall noise on its power rails, some are worse than others, if you are using composite or to some extent S-Video there is usually some improvement to be made by its removal. 65/130XE do need to sort out Audio after as its mixed within the Modulator
I'm back home now, so maybe a few less mistakes as trying to use a phone to post is great fun.