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Need PCOS for M20

karletto

karletto

Member
Joined
Jan 28, 2023
Messages
11
Hi to all !
I found an Olivetti M20 in a friend house, in working condition. It has two ram exapansion and one was faulty, simply removing all seems ok. It has also the double serial interfacecard.
Two floppy version, i suppose monochrome monitor. But i have no floppy of PCOS and is not clear to me how to create.
Can i connect the M20 floppy readers to an old pc and write disks with old tools found in internet ? Or in which other way is possible toc reate from IMD or similar format files?
I wolud like to see it working, just for satisfaction !
I live in IVrea (Olivetti town!) but seems hard to find support here... :-(
THANKSSSS!
 

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Thanks, i know that site but there is no "practical" information about IF is possible to connect M20 floppies to normal old pc.
IF possible i can try to write disks. If not i have to find other 5.25 reader (maybe from M24???) with 360k format to try.
Also i write here in forum because seems there is more people watching so maybe i can have some contact in my city Ivrea. Maybe there is someone of my place using same forum ;-)
 
That's a nice old computer. It was very interesting to see all the proprietary ideas for micro computers back then in the early 80's. Unfortunately some of the choices made make it more difficult to communicate with what became the popular choice for PC's - the IBM PC and MS-DOS. I own a NorthStar Advantage that was made around the same time. They offered an 8088 card that would allow it to run MS-DOS. But it was far from PC Compatible.

I'm no expert, but I suppose it would matter what disk formats are used and whether you can write to that format. Do you have any other old computers? An old PC Compatible maybe? When I got my Apple IIe it did not come with any disks. I was able to cable it through the Super Serial port to a PC and ran some specialized software on the PC to load into the Apple IIe and then I was able to transfer files from the PC to the Apple and write disks using the Apple floppy drives and some old 360k PC diskettes. Maybe you can do something similar with the M20.

That site linked by @chris-uk seems to indicate that it was possible, at least back in 2005-2008. There was a notice posted in 2022. Maybe it is still active and can get you started.

Good luck,
Seaken
 
karletto said:
Hi to all !
I found an Olivetti M20 in a friend house, in working condition. It has two ram exapansion and one was faulty, simply removing all seems ok. It has also the double serial interfacecard.
Two floppy version, i suppose monochrome monitor. But i have no floppy of PCOS and is not clear to me how to create.
Can i connect the M20 floppy readers to an old pc and write disks with old tools found in internet ? Or in which other way is possible toc reate from IMD or similar format files?
I wolud like to see it working, just for satisfaction !
I live in IVrea (Olivetti town!) but seems hard to find support here... :-(
THANKSSSS!
Click to expand...
Hello and welcome to the forum.

I think that you want to connect the M20 floppy disk drive to a PC, is that correct? It may be possible, however if the floppy drive does not have the same connector/number of pins as the floppy drive cable on your PC, it is probably easier to find a PC that has a working floppy drive already. Please note the the M20 could have come with one of 3 different types of floppy drive, according to the document at http://www.z80ne.com/m20/sections/manuals/hw1.pdf (see page 10).
 
Hi, the z80ne site has instructions for using PCs with 360kb floppies to produce pcos files. Not all controllers are supported though, because the first track is formatted in FM and not MFM. The m24 should work, but I never tried myself.

Regarding the floppy drives, the m20 drives have identical signal cables but the power supply connector is +5,gnd,+12,+12 instead of the standard +5,gnd,gnd,+12.

Another option is to attach a gotek to the m20 (adapting the power supply cable, you only need gnd and +5) and transfer everything quickly. I posted the configuration files in another thread.

BTW, I created an ide Hd controller, a replica 8086 board for the m20 and a vga/memory card (the last I am waiting to get back from China, so I don’t know if it works yet).
 

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Hi ! Thaks to all. Yestarday I had SOME success connecting the floppy reader of M20 to old Peniumt 200 pc. Are 360k floppy readers. I connected floppy 1 as A: but with power from M20 itself (i discover now the different layout of power connector!). In this way i was able to read and write msdos floppy ! NOT to format, format failed in some strange way . Also i wrote M20 images pcos disk with IMD tools (seems great tool) BUT are not read by M20 itself after, i get an error 18 on disk at boot. Probably the sector 0 is not wrote in right way. I need a pcos floppy to really start to make other images so i can format other floppies.... Hope to find in my city if not i'll beg here or somewhere ! :)
The "replica" cards are GREAT, my compliments !!!!
There is any italian guy here by the way ? Just to understand...
 
Make sure you are using a 360K drive. Even though you can read an write to a 360K disk on a 1.2M drive it will not work on a 360K drive, unless the disk is completely magnetically erased. Even then it may still have issues. A I recall the M20 drives are standard 360k drives. You should be able to use them in a PC with the correct jumpers selects.( note the PC does not use jumpers that match the drive specifications so it can used the twisted ribbon cable in the PCs. ). Also, you mentioned that you had 2 RAM cards. Are the cards populated with 16K chips or 64K and are they the same size on the motherboard ( they can't be mixed ).
As was mentioned, you need a controller that supports 360K. They don't all do that.
Dwight
 
The first track is written in FM and the rest is written in MFM. I'm not sure which tools support creating disk that way. I'm going back some in my memory but I recall, I had to create the first track with a controller that supported FM or use the M20 to do it. It has been a long time since I did this. Make sure your controller supports FM. There are some test for one of the tools that checks FM capable controllers. I just don't recall which.
Are you in the USA or Europe?
Dwight
 
Hi ! I'm in Italy, Ivrea, the town of Olivetti ! :) I "solved" the problem thanks a good menber of this forum TPAXIA, he suggested me to connect a Gotek (i have connected from years to an Amiga) and gave me a good pcos file .img to start. He made also the def file to use it in Gotek. So i have drive 0 the Gotek and drive 1 a floppy of old M20. It boots good, 160 k ram. I formatted also some floppy on floppy reader and copied pcos, boot is good also from real reader. So i i have a M20 working ! I need to clean the keyboard, a couple of keys are not working well. Now i need to understand how to convert IMD files to IMG and use also these with Gotek. The real floppy driver of M20 connected to an old Pentium pc was workig with msdos floppies BUT not able to make "good" pcos disk, for sure controller is not able of FM. But now that problem is solved, i have some of my old DDDS floppy to experiment and the power of Gotek to enjoy !
 
Thanks, i did it ;-) Some link on the famous m20 site are wrong, i wanted to try Pascal (i used at 1' university year) but all 4 links are the same disk . Not a big problem anyway
 
If somenone is interested i found a torrent with ALL the available software (always almost the same but pascal is correct 4 disks for example) and i made a small batch to "injects" the sector 0 to have a good img for gotek usage. Then you can create real floppy on a M20 ;-)
 
You'll need more memory to run the Pascal. It requires 384K. At least the version I had did. I think you had a 128K system. But you didn't reply with the RAM chip size you have.
Dwight
 
Yes i see on manual, no hope for me, i have 160k (plus a 32k not working). Anyway in m20 site the link of pascal are wrong, all same disk 1. I wrote to owner weeks ago but no reply, maybe is no more looking at it...
Not a big problem, at university i maed all in Turbo Pascal on pc, was really a smarter tool ! ;-)
 
You can convert the m20 to us 64K DRAMs. I did this on one of my machine several year ago. The motherboard is fairly straight forward but there are some issues with a supply rail being where one needs an address line on the RAM boards. It can be done. I couldn't tell you all that needs to be done ( too many years ago ), just that it can be done.
You can't mix 16K chips and 64K chips. It is an all or nothing type of thing.
Dwight
 
No thanks ! I'm informatic guy, not electrotechnic ! I'm not good in soldering and that stuff, only basic level (and maybe less than basic). So now the M20 is working good, i have all software possibile, i create floppies of PCOS and main programs just for "satisfaction" and maybe i'll sell it, a my friend (a lday) gave me tro trash but now is working and has some value so is correct to give her the money i can get. I dont like to "gain". I have already enough vintage stuff at home (from Zx Spectrum to C64/c128D, Amiga...etc..etcc.....not considering vintage hifi...) so no more space to have also "old style" professional pc. Was really a "special" machine and for sure there is some man that can be happy to have it in his personal museum. Is like new (used very few at time) , perfect working, double serial interface : anice toy. If i try to make some hardware mod...i can sell as trash ! ;-) So thaks for support and for suggestion, you all made my pcos "reborn" !
 
Dwight Elvey said:
You can convert the m20 to us 64K DRAMs. I did this on one of my machine several year ago. The motherboard is fairly straight forward but there are some issues with a supply rail being where one needs an address line on the RAM boards. It can be done. I couldn't tell you all that needs to be done ( too many years ago ), just that it can be done.
You can't mix 16K chips and 64K chips. It is an all or nothing type of thing.
Dwight
Click to expand...
Hi Dwight, I think I found a better way to do it: you can add RAM on the expansion bus instead of the 3 separate memory slots... The trick is to disable the mapping prom (with the MEMDIS signal) and provide a new memory map on the expansion board. There are a few quirks regarding the boot and the eprom access, but it's all fairly straightforward.

If you really want to use the memory slots, it takes very little to design a 128kb card with 4x64k drams...
 
I suppose here there is some original M20 project manager or the son maybe... ;-)
 
Hi Tpaxia
How do you mix 16K and 64k chips. I thought the only way was to switch from 16K to 64K on all motherboard and expansion cards. It is not just a way to fiddle with the ROM, the 64K requires a different refresh addressing, using the jumpers and such on the motherboard.
I did have to make a jumper wire for the address on a modified 32K memory card, making it a 128K card.
Dwight
 
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