Re: Help identify 2 missing components on MORSE KP-386C 25MHz 386 maiboard

Posted on 2015-05-15, 19:19

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for describing the picture, I can now read the picture better and see one quite short leg of the capacitor (the crystal legs are huge in comparison). But for a certain job, there is a certain capacitor type (or a few..), and crystal circuits commonly use ceramic caps, because they are the …

---

Re: Help identify 2 missing components on MORSE KP-386C 25MHz 386 maiboard

Posted on 2015-05-15, 16:04

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Where do the crystal traces go to? If it is 8 MHz, I suspect it is for the keyboard controller. (Crystals of that size can also be the 32768Hz crystal for the real-time clock, but it seems there is another small crystal near the chipset which might be the RTC clock). It really looks like something …

---

Re: Using a network card for providing BIOS extensions

Posted on 2015-05-07, 11:24

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've succesfully been involved in a project where we burned a piece of code to an (E?)EPROM and put it on a network card for booting it. I recall we had to burn the same binary image many times to fill the memory chip as we had no idea which part of the memory chip was mapped to ISA memory space. …

---

Re: Can somebody help me fix my MPU-401 MIDI player?

Posted on 2015-04-30, 16:39

by

by Jepael

in DOS

in DOS

Sure. How would you describe it does not work? Do you think problem is more in the loading the .MID file or playing it? Can you give a sample .MID file so we have the same data to play? (Link is fine, or the file itself) It seems there's plenty of other stuff required, so I can't just copy-paste …

---

Most supported .VGM file version?

Posted on 2015-04-24, 18:19

by

by Jepael

in Milliways

in Milliways

I am logging OPL2/OPL3 data and trying to create .VGM files, should I just use the latest VGM specification with all the latest features, or should I limit VGM file to some older version? Which versions are most commonly supported by players and tools so everyone could easily play/edit the files?

---

Re: Please help me fix my VGA emulation?

Posted on 2015-04-23, 06:27

by

by Jepael

in PC Emulation

in PC Emulation

I don't think you understood SarahWalker. It is not the Dot Clock Rate bit that is used here. You really need the attribute controller register 0x10, bit 6 to be in 256-color mode, and maybe some other registers too. Mode 13h is really a 640x400 mode if you look at pixels and lines. Thus no DCR bit …

---

Re: Does the VGA cable matter?

Posted on 2015-04-21, 06:16

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Picture quality is a product of the whole system, the video card (and maybe even noisy parts like PSU or hard drives near it), the cable, and the monitor. Blurriness is a definite sign of bad something that causes attenuation of high frequencies, usually the cable though, but it could be bad …

---

Re: Paradise PEGA programming info (Amstrad PC1640)?

Posted on 2015-04-18, 19:31

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

OK, thank you. I will check the DISPLAY software and I appreciate the effort you have already taken to try to get datasheets, I know it's not easy.

---

Paradise PEGA programming info (Amstrad PC1640)?

Posted on 2015-04-17, 18:18

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi, does anyone have any pointers where to find datasheet or programming info for Paradise PEGA chipset that is onboard an Amstrad PC1640? The same PEGA chipset is used also on some discrete EGA cards. I believe it is a PEGA1A version. Basically I know it is able to switch between MDA and EGA …

---

Re: SCSI Termination Question

Posted on 2015-04-07, 08:26

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Adaptec manuals and other documentation for this card is still available on Adaptec website, so it's best to start from there.

---

Re: SD to IDE not booting - any experience?

Posted on 2015-04-06, 18:42

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

They don't have a weird write protection, but when fiddling with anything that may touch the partition table, it is possible that the card ends up being looking like a floppy (no master boot sector like fixed hard drives, starts with just partition boot sector like removable floppies).

---

Re: Can NOT get a mouse detected....

Posted on 2015-04-06, 08:19

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Check if the power supply is OK. Mice need both +12 and -12 volts, you can also measure the actual voltages on serial connector to be sure if these voltages really go all the way from power supply to the ISA card. Also check if you have the correct adapter bracket as back panel brackets with serial …

---

Re: SD to IDE not booting - any experience?

Posted on 2015-04-04, 20:57

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The original partitioning could use different geometry from your BIOS. Dos uses CHS anyway, not LBA, and the way the BIOS maps LBA to CHS may differ what from what kind of partition table the card manufacturer thought it would be nice to use as CHS parameters. I'd try to zero out the partition table …

---

Re: Newly made Gravis Ultrasound compatible cards ... what's the degree of interest?

Posted on 2015-04-01, 12:41

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

I'd suggest something in the lines of "GUS NEXT", but the G part won't apply here. We all know it's not GUS, so "NOTGUS" almost sounds like a word. Does "UltraSound Next" sound bad? Can it have the InterWave word? "InterWave Deluxe"? "InterWave Unity"?

---

Re: Small warm up project - Gameport/MIDI box

Posted on 2015-04-01, 08:59

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The schematics look certainly good to me. I don't think the 200 ohms will interfere and you have good reasoning to determine the value (the impedance is not purely resistive either, but you can approximate it as they say in NXP datasheet that when 5.2mA is sunk in by the output, the typical low …

---

Re: Small warm up project - Gameport/MIDI box

Posted on 2015-03-31, 08:21

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Relax. It wasn't a critique. Just an observation from my own experience. As in most things in the EE world, there are absolutes and then their are design approaches of varying style and purpose. Just providing the OP with a little perspective. More perspective and more discussion is a good thing, …

---

Re: Small warm up project - Gameport/MIDI box

Posted on 2015-03-30, 18:49

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well Avago recommends the 100nF bypass, and Vishay and Fairchild have them drawn in their datasheets. Only Toshiba does not have any reference to any bypass cap. I know it is not a traditional digital logic chip, instead it is a very sensitive photodetector and the thing will be switching more than …

---

Re: Small warm up project - Gameport/MIDI box

Posted on 2015-03-30, 15:51

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I made this kind of thing about 10 years ago, so I have few suggestions. But I never used mine much, as I got my Gravis MIDI adaptor back shortly afterwards. Your other DIN connector is wired incorrectly. Midi cables connect straight through so if you connect 2->2 and 4->4 in your PCB then you'll …

---

Re: Outputing two sound cards to one set of speakers (hardware)

Posted on 2015-03-18, 19:53

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You could use that cable to connect one output to two different inputs. But you cannot connect two audio outputs directly together into one input and expect it to work. Most likely it won't break anything though. (An analogy, you cannot have two amplifiers connected to one speaker at the same time). …

---

Re: Can anybody help me debugging the MS-DOS 3.3 boot process?

Posted on 2015-03-16, 18:47

by

by Jepael

in PC Emulation

in PC Emulation

Well it loads to the top of available memory your int 12h tells it. If you say you have 640kb of memory available, you don't have EDBA and it loads top of memory. If you do have EDBA, you have 639kb of memory available, and it leaves the last 1kb with EDBA untouched and that is why it is loaded 1kb …

---