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I see you use symbols with package-based layout. Down the road, the schematic may be easier to read using symbols with a logic layout instead. For instance, for the 74LS273, if the symbol groups all the inputs in order on one side and all the outputs in order on the other side.

I see! Yes, checking where the IO write ends up is what I'd do too. I would suspect it ultimately ends up at the gate array chip at some point. If you trace the signal all the way to the gate array, along with the accompanying address and data paths/control signals, if you got the tools and are...

If you can get code running and modifying RAM on the 286, that's a good start. Then you can execute small bits of code on the 286, and read the result back on the host. In this case, the first thing I'd do is to get together a small program for the 286 to test all the RAM. A bit more thorough...

On the topic of other things that almost got sued for allegedly copying CP/M, was the operating system for the Z80-based Norwegian computer Tiki-100. Conveniently they called it KP/M, so it certainly hit a sore spot! Their counter-claim, published in the news at the time the case came up, was...

Yeah, I found that thread shortly after I posted here. ..And please do! I would be very interested if you have spare boards.

I've been looking at some disk images containing the Tandberg TOS operating system, and I was curious about how much of their choices they came up with from scratch and how much is re-used from other products. This OS was made and used with the TDV-2114 8080-based computer in the late half of...

I know its an old thread, but I am finally getting one of these myself. Additionally, I see that Siemens later released this platform as the 6.600 series. If anyone happens to have any documentation (even if it's in German), I would be very grateful to see it.

I've had faster DRAM chips (80ns) be unstable in a 4MHz machine before. That was not due to faulty chips, but rather the fast transients causing issues with how the PCB was laid out.

It has to be said that many RAM tests does not detect if you use 64k chips in a 256k bank. Everything will appear work fine... until DOS (or wathever is ruinning) uses more than the first 64KB of that bank. For the 5160, two more modes are available other than the mentioned 64k-256k and...

I'll try to dig it up from my digital archives, but as mentioned it turned out to be extremely similar to the MINIBUG module. If I remember correctly, the only significant differences are the starting address its assembled for and the IO port used for the communication interface.

I can say for sure that I do have had this problem with the MOSTEK 36xxx series, in particular gold cap ceramic ones like the ones here. In my case the set of failing ROMs were from a HP 3456a voltmeter, and dated around 28/29th week of 1980.

There's a few other similar layouts across a few different boards if you just search for the chipset, so it might have been based off a template. All of the others are SIPP though. Here some of the pictures and the diagram is with discrete chips at least. TheRetroWeb is a volunteer project, so...

I did a search on TheRetroWeb, and it kinda looks like this: https://theretroweb.com/motherboards/s/biostar-mb-1212v

I'm putting this out here just in case. Getting technical information on these old digitizers seems to be quite hard as these were never plentiful in the consumer market. In any way, lately I have been working on figuring out the settings to a digitizer board I have of the type Numonics 2210...

Thank you very much! Yes, the card I have was just a Orchid PCTurbo 286e. The card I was speaking about was the earlier 186 version also from Orchid.

One question, I see from your pictures that you have a more recent TDV-1200 using a keyboard with the 967043 matrix board (also used for the Tandberg PC-compatible keyboards). I am very curious on what controller board and firmware your keyboard is running. I do have a pair of two identical...

I know for certain that the Olivetti M24 did at least use 80-track double-sided double-density drives, and could come with them in a stock configuration. Maybe the American edition, the AT&T PC 6300, used it too.

I am going through and once and for all properly archiving my collection of floppy disks, and from time to other I come across 48tpi disks with a peculiar 128-byte FM-modulated tag on head 0 of the 41st cylinder. Sometimes it is also accompanied by empty tags on head 1 and both heads of the 42nd...

I recently got myself a MEK6800D1 I decided to get back up to working condition. After doing some research, I figured that the MIKBUG and MINIBUG portions of the ROM are well documented, but the Engineering Note 100 only lables the last 256 bytes of the ROM "Pattern Data", without ever...

I am at the time working on imaging some 8" floppies written by a Norsk Data machine once, and right now I am trying to figure out the file system. I do find something that looks like a directory structure on the 77th track, but I am having problems finding any information what the numbers mean...