View Profile: tonata - Vintage Computer Forum

Today, 01:51 PM

modem7 replied to a thread Z110 PSU +12V not working in Vintage Computer Hardware

See the photos of electrolytic capacitors at here]. By "triangles", I presume that you are referring to the triangular segments shown in the second...

9 replies | 58 view(s)

Today, 01:42 PM

modem7 replied to a thread High-capacity disk read errors on an AT in PCs and Clones

You are not seeing any issues at all using 360K floppies, so this does not sound like a 'dirty heads' issue. What is the background of the subject...

3 replies | 48 view(s)

Yesterday, 01:53 PM

modem7 replied to a thread IBM 5170 restoration - PSU fixed, now RAM problems - SRAM replacement? in PCs and Clones

I am not following you. The parity calculating hardware (for motherboard RAM) is elsewhere on the motherboard with the piggyback DRAM's in the...

5 replies | 132 view(s)

January 15th, 2021, 01:48 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

In case you did not see it, mentioned at here] is the availability of prebuilt AT2XTKB (and some variants) on eBay.

22 replies | 425 view(s)

January 14th, 2021, 08:20 PM

modem7 replied to a thread Good program for polling all the IRQs, DMAs, I/O hex addresses? in Vintage Computer Software

Some other issues: * The RAM on some network cards does not appear in the motherboard's memory space until the driver for the card is loaded....

5 replies | 133 view(s)

January 14th, 2021, 08:03 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

C5 and R9 run from ground to +5V. When you have the keyboard plugged into the (unpowered) motherboard, measuring the resistance across C5 (or R9) is...

22 replies | 425 view(s)

January 14th, 2021, 07:07 PM

modem7 replied to a thread Getting an 8" FDD working with an IBM 5170? in PCs and Clones

In the past, I have tried to fit various half-height hard drives under the two floppy drives, but from memory, there are issues like the screw holes...

14 replies | 194 view(s)

January 14th, 2021, 07:01 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

Consider too the option of an AT class keyboard together with an adapter like the one at here]. BTW. I updated the circuit diagram even more.

22 replies | 425 view(s)

January 14th, 2021, 04:41 PM

modem7 replied to a thread Getting an 8" FDD working with an IBM 5170? in PCs and Clones

As far as I am aware, the subject card will simultaneously support up to two floppy drives and up to two hard drives. The limitation you write of...

14 replies | 194 view(s)

January 14th, 2021, 03:43 PM

modem7 replied to a thread IBM 1501492 - dead? in PCs and Clones

Further to last: I am "jumping the gun" here. If, via what I suggested, it is revealed that the controller is overloading the PSU, then there...

6 replies | 116 view(s)

January 14th, 2021, 02:09 PM

modem7 replied to a thread IBM 1501492 - dead? in PCs and Clones

Welcome to these forums. By your "The PSU starts", I am assuming that you are basing that on the fact that the PSU's fan is turning. If so,...

6 replies | 116 view(s)

January 14th, 2021, 01:47 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

I am very experienced in 'recreating' circuit diagrams. But it is still easy to get confused. For example, this morning, I realised that I had...

22 replies | 425 view(s)

January 14th, 2021, 01:16 PM

modem7 replied to a thread Adding a CF card slot to a 5170 without wasting an expansion card bay? in PCs and Clones

On that subject, after a prompt weeks back from member Malc, I did some more experimentation, and I now have a VCF XT-IDE card that appears to 'play...

21 replies | 498 view(s)

January 14th, 2021, 09:27 AM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

I found the specification: 275 VAC.

10 replies | 421 view(s)

January 14th, 2021, 07:43 AM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

C5 and C6 are on the alternative or direct current in the power supply? I just realized that capacitors have different ratings for that. So mine...

10 replies | 421 view(s)

January 14th, 2021, 03:05 AM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

Suggesting that when the keyboard is attached, the motherboard is seeing an AA byte from the keyboard. First, look at here], the circuit diagram...

22 replies | 425 view(s)

January 13th, 2021, 09:08 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

That is odd. I would have thought that at least one the two motherboard you have used would have displayed a keyboard related error. If you remove...

22 replies | 425 view(s)

January 13th, 2021, 02:11 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

Some keyboards (perhaps most) do some sort of self test as soon as they receive power, with that self test momentarily flashing on the LED's. With...

22 replies | 425 view(s)

January 12th, 2021, 11:31 PM

modem7 replied to a thread IBM 5170 restoration - PSU fixed, now RAM problems - SRAM replacement? in PCs and Clones

If you are using IBM software, the author is probably assuming that only IBM options are used, e.g. for base memory, settings of 256K, 512K, and...

5 replies | 132 view(s)

January 12th, 2021, 06:48 PM

gekaufman replied to a thread Need recommendation for a broken floppy header replacement in Vintage Computer Hardware

I don't think I'd bother - I believe all of the odd # pins are ground. Missing one shouldn't be a problem. The breakaway headers should be fine...

5 replies | 119 view(s)

January 12th, 2021, 06:30 PM

modem7 replied to a thread IBM 5160 ? about XT-IDE in PCs and Clones

If you look at the memory map at here], a start of C0000 will be a problem if your IBM 5160 has an EGA or VGA card. A start of C8000 will be a...

10 replies | 341 view(s)

January 12th, 2021, 06:21 PM

modem7 replied to a thread IBM 5150 - RAM refreshing in PCs and Clones

I have added a couple of new sections to the end.

3 replies | 169 view(s)

January 10th, 2021, 12:24 PM

modem7 replied to a thread 4xAA BIOS battery replacement not working in Vintage Computer Hardware

On the DataExpert EXP8049 motherboard, the external battery header, J1, is used for both an external battery, and as required, to clear the 'CMOS...

47 replies | 1488 view(s)

January 9th, 2021, 10:14 PM

modem7 started a thread IBM 5150 - RAM refreshing in PCs and Clones

I decided to better understand the dynamic RAM refresh circuitry on the IBM 5150 motherboard. I documented that at here], not only for others, but...

3 replies | 169 view(s)

January 8th, 2021, 01:51 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

At here], 'Datacomp' appears on a keyboard's controller chip that was made by Signetics. It is as though Datacomp paid Signetics to supply a...

22 replies | 425 view(s)

January 8th, 2021, 01:14 PM

modem7 replied to a thread 4xAA BIOS battery replacement not working in Vintage Computer Hardware

Yeah, but my post has pretty pictures, something sure to illicit a response. :-) I didn't ask about the 'oscillator' pins, because from what I...

47 replies | 1488 view(s)

January 8th, 2021, 02:27 AM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

Now that you said it I had an extra look (or maybe it is because I finally got some light) and I suspect these two big capacitors: They have...

10 replies | 421 view(s)

January 8th, 2021, 02:11 AM

modem7 replied to a thread 4xAA BIOS battery replacement not working in Vintage Computer Hardware

Looking at the motherboard photo that you pointed to in post #20, the motherboard contains a 'Chips & Technologies' P82C206 chip (the square chip)....

47 replies | 1488 view(s)

January 8th, 2021, 12:47 AM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

Wow it worked !!! 1) Moved the monitor to a warmer environment (in the living room :p) 2) Made sure it is connected to an electrical socket with...

10 replies | 421 view(s)

January 7th, 2021, 03:15 PM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

So I just measured the video card. It starts in mode 1. After 1 ms pulses switch to mode 2. Per here pulses do correspond. Switches P1 and P2 are...

10 replies | 421 view(s)

tonata
Member

Mini Statistics

More 3 Friends

modem7

gekaufman

zinamo

Recent Visitors

Basic Information

About tonata

Statistics

Total Posts

General Information

3 Friends

gekaufman

modem7

zinamo

tonata Member

Mini Statistics

More 3 Friends

modem7

gekaufman

zinamo

Recent Visitors

Basic Information

About tonata

Statistics

Total Posts

General Information

3 Friends

gekaufman

modem7

zinamo

tonata
Member