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Yes, a 4K font ROM dump is a collection of 256 glyphs, 16 bytes each, of monochrome bitmap. With some googling around you should be able to find an editor that can handle 9x14 characters of an MDA/Herc. Here's the ROM dumps of the four above to get started. Note that your ROM chip might be...

Certainly. You will need to swap the font ROM though, you won't do it programatically. Here's the MDA 9x14 charset in KEYBCS2, Russian, Latin 2 vs. the original CP437:

... and just to be sure, write protect it. I once had a stealth boot virus in the MBR of a certain hard drive, infecting me a couple of DOS boot diskettes. The only other payload was to redirect subsequent writes to the boot sector, MBR and partition table of any drive present, so that it...

Seconding @bitwhacker here with the lightbulb idea, naturally the bulb needs to be of incadescent type, but a higher wattage is preferred - starting at some 100 watts. This is because some circuits such as PSUs or other capacitive loads might present an inrush current that cause the bulb to...

Haha, well actually both the monitor receptacle and the power switch/fuse holder were originally encased behind a grounded sheet metal piece... at least, this case revision did. This is because the original wiring left the receptacle hard wired live, even with the power switch down, and the old...

Continued from above: A full-length PC ISA card compared to the system cards. Minimum setup running Ruud's diagnostics. The "processor card". Actually, all of the system cards contain a wacky mix of AMD, Fairchild, ST and Siemens parts interleaved with COMECON counterfeits from the...

An addendum to romanon's topic from almost ten years ago, avoiding thread necromancy and adding some technical quirks and details: one of the PC/XTs from Czechoslovakia, the Tesla SMEP PP 06, produced between 1986 to around 1990. With the Western embargo having eased up a little, it was evident...

I think you know about this one already as I once used the parallel interface as a boot option, similar to what XTIDE has over the serial port, this one a tiny bit faster: to boot a late 1980s ARCNET diskless thin client over the "laplink" cable, switching to an INTERLNK session once CONFIG.SYS...

Is that a genuine SBPro or a clone? Inside the DOS test application, note down active base address, IRQ and DMA channel. Put those values into an environment variable BLASTER (using SET BLASTER into autoexec.bat), quoting Endersending's example it would be SET BLASTER=A220 I5 D1. Now if it is an...

Here's a direct video and audio hookup from the real hardware Junior to a cheapo USB capture device (the RCA jack contains PC speaker output too, probably through a bandpass filter); compared against the MESS/MAME32 emulator of the same machine, with the same boot floppy and same...

"Uh... uhh.... Hwat we got heer is.... failure to emulate"... :) Of course not. Try switching to "rate" instead of "square wave" generator for channel 0 of the 8253, i.e. change mov al,36h to 34h in the setup_timer routine. That should do it - better yet, use a proper vintage hardware...

It's FASM. What kind of errors do you get?

Well, so I thought. If I wire in an unsigned 16bit mono sample and program the speaker timer output channel with 16 bit values each IRQ0 tick, then the result is a complete silence from the speaker. If I switch the endianness or use signed PCM without changing the code, then there's some...

Sadly I don't think so, it just doesn't have enough resolution - it's always speaker hard on or off. No dynamics to the sound, and since it's constant amplitude square waves, the resultant distortion from hard clipping. If you take a look at the source code of PCM2PWM.EXE in my "Tom and Jerry"...

Yes, I have some rants about connecting an 8" drive to a PC on my blog here. It's quite a long read since there's no universal schematic when it comes to these old dinosaurs, but you can then use various utilities such as IMD, cpmtools on the images etc. However, if an Arduino and a soldering...

Nope, I'm referring to rallen's improved SOUND4 attachment. Have a look at the whole thread, there's 2 ways of driving the speaker for digitized sound, 1-bit and 8-bit. And I kind of hate to repeat myself all the time.

He's actually doing eight bits here. On a PC the PIT has 3 channels: channel 0 for the IRQ0 timer, channel 1 for XT RAM refresh and channel 2 for the speaker and 5150 tape interface. For digitized sound output through the speaker, you have two options basically: directly flip the "speaker...

It's good enough with some background whine. You won't get the loudness of 1-bit PWM, then again, not the distortion either, which is what you don't want. Unless you're playing loud screams, wacky gunshot noises or Austrian painter's fits of rage. I have a video of that too, but I won't risk the...

Yeah, it's better now. The only issue is that on a PCjr, the keyboard is handled differently so it won't react to any keypresses here, Escape included. I think you don't need to concern yourself about that since the Junior had been a blind development path, but if you want to, you can inspect...

An 8" drive requires a floppy controller with a 500kHz clock with FM and 128byte sector support. The Diskette Drive Adaptor in an IBM 5160, although based on the NEC 765 chip, will not work in this configuration as it is hard wired for a fixed data rate of 250kbps MFM. Also, PC floppy drive...