Years later something random happens (AT&T PC 6300 journey)

[OrangeJacketGuy]

Some time has passed since I last posted in December 2022. [here]

Life can often get in the way of things and getting my AT&T PC 6300 was naturally a lower priority. Some years passed and I never truly got back to getting my Olivetti M24 clone until the most random of things happened. I was going to the Reuseum last month to get a few resistors and misc items (btw, this is a place you should visit when in the Boise area). Upon approaching the storefront, I saw the unmistakeable backside of an M24. I thought my brain was playing tricks on me but sure enough, when I got in there it was in fact what I've been pining for. I was kinda pressed for time so I didn't check it out at that point. I was kicking myself for not picking it up, and a few days later I came back and got it, without even really inspecting the machine.

Rushing home with it, I DID remember to immediately remove the RIFA cap and the battery. Being that far into the power supply, I saw that it was merely dusty but otherwise ok. I grabbed a semifuncitonal IDE drive to act as a load for the 12v and 5v lines. The rest of the machine passed visual inspection. There was an MFM controller card in there, but no drive or even the rails for floppy drives.

I knew it was going to be a while even under best conditions and some luck to get any video out of it, but I plugged it in anyways and I heard the rather distinctive beep that I hadn't directly heard in decades. For an unrelated project I had a Tandon TM 100-2A, and I hooked it up just to see what would happen. I'm 99% sure that the motherboard was getting so far as to attempt to read from floppy, which means that a bunch of other things are also likely working. Yes, I understand that I'm very lucky in that regard.

I hadn't bothered reading up on the clock situation until now. I didn't know that the battery situation is basically pointless to fix, given that it's apparently not even Y1992 compliant. I've been watching a lot of Tibo's Youtube channel again just to refresh myself on the road ahead.

I'm probably going to put the MFM controller on eBay since currently it doesn't look to be directly useful to me. It is an SMS/OMTI Model 5520 REV D. I'm also arguing with myself on whether just to power through using the original display hardware and an RGBtoHDMI with a little bit of custom cabling, or to somehow get an 8-bit ISA VGA card. Both are going to be a bit of effort. Perhaps someone can settle the debate?

There's also the looming issue of the keyboard. I really don't want to get an Olivetti keyboard as I don't have good memories of them. I am aware of a post from years ago about a possible alternative but we'll see what happens.

If I start getting anywhere with necessary hardware I still might do videos on it.

Thanks again for your time.

 

[1ST1]

The 6300 is not a clone of M24. It is a M24. The 6300 was made in Italy by Olivetti. It's exactly the same thing.

You can replace the MFM controller by XT-IDE, but be carefull on choosing the corect BIOS version for it, there is a special one for M24/6300/6060.

RGB2HDMI might be difficult as M24 has CGA like signals, digital colors with intensity signal (RGB-TTL), main difference is higher clock frequencies as original CGA. RGB2HDMI is for analogue RGB signals.

VGA card is diddicult as you can't disable the integrated graphics card. You even can't remove it as it is the bridge between mainboard and ISA slots.

They keyboard is difficult to replace by other one, it is using XT protocol plus some enhancements/incompatibilities. You may make an adapter, but not every keyboard will work and with some you will have dead keys. You can't use AT protocol keyboard. M24 BIOS may complain about the keyboard at BIOS post as M24 sends some comands to the keyboard which standard XT keyboard can't understand.

 

[OrangeJacketGuy]

Sorry about misspeaking there. Yes I am aware that the AT&T PC 6300 and the Olivetti M24 are the same computer.

I was able to get the RGBtoHDMI working well enough. It is not dialed in completely, but I think I'm mostly there. I was able to wire the CGA-like lines into a DB9 connector that the RGBtoHDMI wants along with breaking out the +15v from the M24 to power it through an LM2596 board. It's hacky but proves it can be done.

I was able to hack together a dummy load from a 10ohm and an unused processor heatsink. It worked for a little while until it started hissing. So I put an IDE drive back in there to act as the dummy load for now.

I have to confess to using Grok to figure out the floppy situation. I got a GoTEK and for some reason Grok was insistent on flashing it with flashfloppy. I managed to get the GoTEK working with the M24 and the machine is definitely booting properly with some AT&T MS-DOS images that I downloaded forever ago.

Also, I'm pretty sure the original case fan is on its way out, so I managed to get a more modern one working in there. It still makes a lot of noise but I don't think it's entirely rational to expect an M24 to be a silent computer. Old computers are supposed to make noise.

I think I'm going to go the XT-IDE route after I square away the keyboard situation. After getting really depressed about it on ebay, I've decided to try the keyboard emulator route.

I'm not able to type in the date or time yet, but I remembered that if you had an appropriate AUTOEXEC.BAT file under DOS, it wouldn't ask. So I can basically do anything not requiring active input lol
I whipped up just the most basic files for booting and had autoexec start "packman". Back when I was a little kid I spent many hours on Packman but I never got good at it. I'll still need a working keyboard to play it on the M24.

So it's going well.

 

[acgs]

Until you get a functioning keyboard attached, you might try replacing "PACKMANE.EXE" with "CTTY COM1:" in autoexec.bat. You won't have full access to the computer, but you could at least run command-line based programs using a terminal/terminal emulator hooked up to the serial port with a null modem.

You might be able to use more programs if you don't mind looking at the computer's screen while typing on the terminal's keyboard. It all depends on how the program gets its input and sends out its data.