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View Full Version : Possibly getting an M24 - keyboard options



bobba84
September 25th, 2017, 03:19 PM
Hi guys,

I'm currently looking at getting an Olivetti M24 for pretty cheap... but it's box only! I know i can work around the monitor issue but what about the keyboard? Do I need a genuine one? Or are there other options?

Thanks in advance!

Chuck(G)
September 25th, 2017, 04:25 PM
I've seen reports that a PC or PC XT keyboard (not a PS/2 or AT, however) can be used by constructing an adapter.

http://old.pinouts.ru/Inputs/KeyboardAtt6300_pinout.shtml

Note that you'll need a voltage regulator (an LM7805 will work) to drop the +12 to +5.

The scancodes are the same, but the initial conversation is a bit different, so I don't know if it will work.

bobba84
September 25th, 2017, 04:48 PM
Thanks Chuck! Sounds like there's hope for it! I'll check it out.

1ST1
September 25th, 2017, 09:38 PM
Try it with an adapter, but the BIOS selftest also includes the keyboard controller, so hopely the 3rd party keyboard will not fail. Otherwise, sometimes there are single M24 keyboards on eBay & Co. You also can use the keyboard of M240.

The voltage regulator in the adapter is important, as the M24 keyboard connector supplies +12V.

bobba84
October 3rd, 2017, 08:01 PM
Ok, so I got the M24. I can hear it beep and the floppy light comes on, so I think it is at least partially working.

I've made the VGA adapter cable posted here (http://www.olivettim24.hadesnet.org/docs/video_converter.pdf) but get no output on an LCD. I'm guessing it can't handle the signal...

I'd like to put an 8-bit capable VGA card in. I found info here (http://www.vcfed.org/forum/showthread.php?31098-Olivetti-M24-No-POST&p=228088#post228088) about removing two PAL's to disable the on board video? Does anyone know exactly which two? And what motherboard DIP switches work for VGA?

Thanks in advance! I'll hopefully have my childhood computer again!! :D

Chuck(G)
October 3rd, 2017, 08:13 PM
Check my blog thread on cloning PALs, I think I mention it there. It's been years and I don't have the 6300 any longer.

Tiberian Fiend
October 4th, 2017, 01:21 AM
Is the monitor you need a VGA one with a bunch of pins missing? I just happened to have picked one of those up recently for $6 (AT&T branded). I live in the U.S. though.

1ST1
October 4th, 2017, 02:30 AM
The original M24/6300 monitors have a DB25 connector. So any with 9 or 15 pins is not the original.

I would not try another VGA card in there before you know if the M24 is functioning or not. This is because of plugin a VGA card into the M24 without removing/bridginmg the PAL you may damage the machine.

As it does not come up, get a post diagnostic plug for the parallel port of M24 and follow this thread: http://www.vcfed.org/forum/showthread.php?54605-How-to-read-parallel-port-POST-diagnostic-codes The discussion has several pages and somewhere on 1st page I posted a link to such a diagnostic module (costs about USD 5), trixter found all of the codes in BIOS disassembling and on follwoing pages somewhere I posted the full diagnostic codes of the M24.

Trixter
October 4th, 2017, 12:31 PM
While a diag module and checking the codes will give piece of mind to any M24 owner, the fact that he's getting a beep and the floppy drive is lighting up suggests to me that he's completing POST successfully.

I agree do not attempt to put a VGA card in until you've got all other issues resolved. If your existing monitor didn't take the VGA adapter connected to the existing video port, then make sure you've got it wired up correctly, and then try a different monitor. Sometimes older monitors will sync to odd signals better than newer ones. Find a glass CRT VGA monitor as that will always work.

bobba84
October 4th, 2017, 03:03 PM
Thanks for the replies guys!

I may have already tried a vga card in there :( hopefully I didn't do too much damage.

I found the info in the manual about disabling the factory video card. Something about a P4 needing a shunt with connections instead of the PAL but the P8 just needing jumpers changed. I'll have to figure out which card I have and give it a go.

But yes, I believe it's working fine as I can hear the post beep and floppy trying to access.

I'll post back with what built in video card I have and how I go disabling it.... but does anyone know if my BIOS will support the VGA card? The ROM chips say 1.1 in big writing on them.

Thanks,
Bobby.

bobba84
October 4th, 2017, 04:15 PM
Update - Forget about the VGA card, I tried another older LCD and I got video!

It POSTS, but won't boot. A few times it froze randomly on startup but after running a while it seems to reliably finish POST but won't actually boot. It just sits there forever with the floppy light on. I've tried without the MFM card, without the video or keyboard adapter connected, etc but it never gets past there.

I also tried another floppy drive and cable, and a few different boot disks.

Power supply reads 4.95v, 11.7v and 16v

From memory this is how it behaved when I first got it, I tried booting with a disk (blindly) but never heard the drive changing tracks.

Any ideas guys? :)

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bobba84
October 4th, 2017, 06:15 PM
ANOTHER UPDATE: After removing and reseating the keyboard controller chip, it boots!!! I just can't get the keyboard to work... I'll have to check my adapter :)

Thanks for your help as always :)

bobba84
October 4th, 2017, 06:51 PM
No luck with the keyboard :(

I'm pretty sure my adapter is correct, I usd this guide (https://allpinouts.org/pinouts/connectors/input_device/keyboard-xt-5-pin/) and I've joined pin 1 of the M24 to DATA, pin 2 to CLOCK, pins 3 and 4 to GND as well as the centre leg of the LM7805, pin 5 to the input leg, and it's output leg to +5V... it boots to a DOS prompt but as soon as I press anything the PC speaker goes mental doing constant tones. I've tried 4 keyboards including XT and AT switched ones in both modes and a genuine IBM type M.

Update: Tried all 8 keyboard I could get my hands on. Some cause the POST to freeze, some don't. Keyboards with lights will flash once when powered on.

Any ideas guys? :)

Thanks!

Chuck(G)
October 4th, 2017, 09:03 PM
Yes, you're not doing anything wrong, I believe. The reports of an XT keyboard working with an M24 are anecdotal--and I could find no solid confirmation of it. While the scan codes are the same, there is one key difference--and I think it may be holding you back. The M24 keyboard is bidirectional; that is, it can receive commands from the M24 and return responses.

That's just a guess, however. What happens if you try to boot with the keyboard disconnected?

Trixter
October 4th, 2017, 09:29 PM
I'll post back with what built in video card I have and how I go disabling it.... but does anyone know if my BIOS will support the VGA card? The ROM chips say 1.1 in big writing on them.


Typically you needed 1.43 for external video card support, but if you got it working, all power to you :-)



I'm pretty sure my adapter is correct, I usd this guide (https://allpinouts.org/pinouts/connectors/input_device/keyboard-xt-5-pin/) and I've joined pin 1 of the M24 to DATA, pin 2 to CLOCK, pins 3 and 4 to GND as well as the centre leg of the LM7805, pin 5 to the input leg, and it's output leg to +5V... it boots to a DOS prompt but as soon as I press anything the PC speaker goes mental doing constant tones. I've tried 4 keyboards including XT and AT switched ones in both modes and a genuine IBM type M.


The 6300 keyboard is not the same as an XT keyboard; the voltage is different. See ftp://ftp.oldskool.org/pub/drivers/ATT/6300/keyboard_pinout.pdf and ftp://ftp.oldskool.org/pub/drivers/ATT/6300/Documentation/Olivetti_M21_M24_Theory_of_Operation_Nov84.pdf (page 180) for more info. Not sure if that matters, but it might.


The M24 keyboard is bidirectional; that is, it can receive commands from the M24 and return responses.

I believe this is why you need a real M24/6300 keyboard. I've never seen any evidence that an adapter works either.

bobba84
October 4th, 2017, 09:29 PM
What happens if you try to boot with the keyboard disconnected?

It boots fine. But connecting a keyboard ends up with the same result - beeping and no input.

Does anyone in Australia have a spare keyboard? Lol!

1ST1
October 4th, 2017, 09:37 PM
I wonder that it does not boot from the harddisk. Two things to help:
1. You have very old BIOS (1.1), the latest was 1.43. (Be carefull, when updating the Bios, the meaning of some Dip-switches change!)
2. What are the dip switch settings for the hard disk? Use internal hdu support or hdu-controller bios?

bobba84
October 5th, 2017, 01:22 AM
Typically you needed 1.43 for external video card support, but if you got it working, all power to you :-)


I got the built in video working through an adapter, not a VGA card :)

The HDD that is came with is dead, I put an ST-225 in there but it hasn't been LLF'd on this controller, as I can't type anything.

Sounds like I'm stuck without the correct keyboard... Might have to put a wanted post up!

My next mission is to make a boot disk that redirects i/o to the serial port and use a terminal emulator to do a few tests.

Thanks guys :)

Trixter
October 5th, 2017, 08:35 AM
My next mission is to make a boot disk that redirects i/o to the serial port and use a terminal emulator to do a few tests.


Hey, that's actually pretty clever! You might even be able to run some older "MS-DOS compatible" applications just fine that way until you find an M24/6300 keyboard.

1ST1
October 5th, 2017, 09:36 AM
In which country you are? Maybe I can help you with a keyboard.

bobba84
October 5th, 2017, 02:06 PM
In which country you are? Maybe I can help you with a keyboard.

Thanks! But I'm in Australia, it's a long way!

bobba84
October 5th, 2017, 02:10 PM
I figured some pics were due. I always like seeing a machine I'm talking about :)

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bobba84
October 8th, 2017, 07:13 PM
Yay! The COM port redirection worked! I made a boot disk with "ctty com1" in autoexec.bat and set up terminal on my 286, and I got an output!

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I was able to LLF and format the drive and install DOS on it... although got some interesting quirks in the output. I guess some aspects of the LLF and format utilities address the screen directly!
4121741218

Anyway, at least I know now that it's working... I just need a keyboard! :D

Thanks to all for help and advice, as always :)

Bobby.

1ST1
October 9th, 2017, 01:21 PM
Well done!

bobba84
April 8th, 2018, 06:28 PM
A keyboard is finally on it's way to me :) I'll post some pictures once it arrives!

I'm also keen to see if my homemade VGA adapter can get colour out of the factory video card...

Trixter
April 9th, 2018, 10:41 AM
Awesome, keep us posted!

bobba84
April 16th, 2018, 03:45 PM
As promised, here are some pictures!

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I couldn't find the VGA adapter cable I made, so I had to make another one. Please excuse the image being off-screen, it was the first LCD I found that liked the timings and I hadn't gotten further than that. But yes, colour works! Will post more pics as I get around to setting up software / games on this beast.

On a side note, are there Windows 3.0 drivers for the factory video card? I'd love it in colour!

Thanks to all for your help with this... this was the model of my childhood PC and I'm absolutely stoked to be able to relive all those memories. I still have programs I wrote in GW-BASIC on disks on an M24 in primary school, I'll have to see if they still work!

Trixter
April 17th, 2018, 09:36 AM
That's great! You even found the correct keyboard for the M24, nice!

There are Windows 1.x drivers for the 640x400x2 video mode, but I'm not sure if they extended that support to Windows 3.x or not. Windows 3 is not the correct version for that system as you'd need an EMS board to make it usuable beyond simple things.

Unless you have a Display Enhancement Board (DEB), the 640x400 mode is not in color.

If your GW-BASIC programs used SCREEN 100 for the 640x400 mode, make sure you're running the M24- or 6300-specific version of BASIC each computer came with. Regular generic GW-BASIC doesn't support the special 640x400 mode.

bobba84
April 17th, 2018, 02:16 PM
Cool, thanks for the info!

I still have the Olivetti MS-DOS 2.11 that came with my childhood PC, so I'll be sure to use that version of GW-BASIC.

bobba84
April 17th, 2018, 06:49 PM
This thing's being a pain... freezing when trying to INTERLNK or start quite a few programs...

I believe it has a very early BIOS (version 1.1) - the list here (http://http://olivettim24.hadesnet.org/download.html) doesn't even contain it.

So two questions:
1. Does anyone want a copy of the 1.1 BIOS? If so, just let me know how I can dump it using GWBASIC or DEBUG or the like
2. Is the BIOS upgrade to 1.43 as simple as changing the ROM chips? If so, I want to do it.

Thanks!

1ST1
April 18th, 2018, 09:24 PM
With the BIOS update the harddisk type table changes. So you need to set the dip switches for hard disk type afterwards.

And yes, a dump of this BIOS is welcome.

Kazblox
April 19th, 2018, 02:44 AM
1.1 BIOS is very much needed. Can you post photos of the EPROM labels, if any?

bobba84
April 19th, 2018, 02:25 PM
Sure can!

Can someone give me instructions for dumping the ROMS (debug etc)

Bobby.

2icebitn
April 19th, 2018, 06:08 PM
You're probably going to need some sort of utility to do that. Iirc debug itself can only save files of 64k-1 or 65535 bytes. Or you would need a way to append that last byte. If you're saving only 16 or 32k roms I guess it isn't an issue. A utility that runs under dos (and most preferably that isn't hardware specific, i.e used bios and dos calls where the hardware is accessed) that joins files would be most useful in general.