Re: PC Speaker don't beep

Posted on 2017-12-12, 20:07

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The speaker circuitry on a PC is rather crude, and uses +5v. Should be fine to power either a piezo or a proper cone speaker. I've modified PCs in the past, removing the onboard piezo and installing a header instead, then connecting it to a cone speaker. Worked like a charm. Most clone cases would …

---

Re: x86 software vs hardware clocks

Posted on 2017-12-12, 19:57

by

by Scali

in PC Emulation

in PC Emulation

IBM VGA array was originally integrated on the motherboard of PS/2 models, so they were the first implementations, not VGA cards. IBM also made a VGA ISA card, or as they call it, the "PS/2 feature adapter": http://4.bp.blogspot.com/-5WVa9cCQew8/VQXmfp66hMI/AAAAAAAACb0/-TwQG8cepPQ/s1600/20150315_ …

---

Re: OPL2LPT

Posted on 2017-12-12, 11:20

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I wondered why they designed the chip like that anyway. Most chips have a bus interface that just keeps the bus busy until the chip is done. For example, I timed a write to the SN76489 chip, and that was 42 CPU cycles at 4.77 MHz. So about 11 IO cycles. But then I thought: Perhaps Yamaha realized …

---

Re: Technically impressive FM synth music

Posted on 2017-12-11, 21:35

by

by Scali

in Milliways

in Milliways

I found this one recently, on the Crossfire Designs page: https://youtu.be/nfOxZI36xxE Made in a tracker called Easy AdLib. Never heard of it. I really like how it sounds though.

---

Re: OPL2LPT

Posted on 2017-12-11, 21:24

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Not quite; as explained previously by Jepael, there is still additional overhead in the form of parallel-port I/O operations. Essentially, to get the equivalent of one write to I/O address 388H, multiple writes to the parallel port addresses are necessary to simulate what would be handled at the …

---

Re: What retro activity did you get up to today?

Posted on 2017-12-08, 16:12

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I finished my 2 Game Blaster/CMS clone cards: https://youtu.be/kxWg1z-yBl0

---

Re: OPL2LPT

Posted on 2017-12-07, 20:35

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I just built mine, tested it with my Celeron Northwood laptop with my custom-hacked DOSBox, and it works!

---

Re: Is worth DOS programming in these days?

Posted on 2017-12-06, 01:24

by

by Scali

in Marvin \ Software

in Marvin \ Software

Oooo! Do you share the source? I'd like to play with it. Yea, I uploaded the code of that release here: https://www.dropbox.com/s/urrzyy23gtvcc4p/1991donut_final.zip?dl=0 It's a mess... requires Turbo C++ 3.1 I've moved to OpenWatcom since. Which is much faster. However, I never did a straight port …

---

Re: Is worth DOS programming in these days?

Posted on 2017-12-05, 19:13

by

by Scali

in Marvin \ Software

in Marvin \ Software

Templates is one of my "most awesome features" in C++, it is pretty handy. I fully agree! The most awesome template trick I've done is for the Marching Cubes algorithm: https://en.wikipedia.org/wiki/Marching_cubes My implementation has a templatized class for the grid size: MarchingCubes . Inside …

---

Re: Is worth DOS programming in these days?

Posted on 2017-12-05, 17:55

by

by Scali

in Marvin \ Software

in Marvin \ Software

I can't say much about C++ as it seems so monstrous to me. Maybe I'm just too dumb to use it efficiently but after watching some of Stroustrup's talks I was like "Interesting but I'd rather use something simple." Again, this could be the case of Stroustrup throwing pearls before the swine but the …

---

Re: How does Lemmings (for DOS) do in-frame palette switching?

Posted on 2017-12-05, 13:22

by

by Scali

in Marvin \ Video

in Marvin \ Video

derSammler wrote: No, it's used in the entire game. See http://www.mobygames.com/game/dos/california- … mes/screenshots (screenshots marked with CGA "MORE-color" mode). Ah yes, seems you're right! For some reason I only ever saw the footbag part in extra colours.

---

Re: Is worth DOS programming in these days?

Posted on 2017-12-05, 13:18

by

by Scali

in Marvin \ Software

in Marvin \ Software

But it also looks a little boring, so you may after all want to go dos and have to write a more interesting-looking wobbly integer renderer. The real challenge is to write wobble-free integer renderers in DOS. That is what originally got me started on the Just keeping it real-series of blogs: I …

---

Re: How does Lemmings (for DOS) do in-frame palette switching?

Posted on 2017-12-05, 12:55

by

by Scali

in Marvin \ Video

in Marvin \ Video

That's because for CGA, it only works at 4.77 MHz and even then is very complicated. CGA is actually simpler than EGA/VGA, because CGA is synchronized to the PIT. You won't have to re-set the PIT every frame, because you know that a CGA frame is exactly 19912 PIT ticks at all time. 8088 MPH …

---

Re: Problems with AM386DX-40 chip

Posted on 2017-12-05, 01:05

by

by Scali

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Motherboards from that era were hardwired for a single clockspeed. You can clearly see a 66 MHz crystal installed there. This is divided by 2 to generate the 33 MHz clock. This crystal has to be replaced by an 80 MHz one to make the CPU run at 40 MHz (but I can't guarantee that it will work properly …

---

Re: CVX-2 : covox adapter

Posted on 2017-12-04, 22:36

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

My reasoning just was that the plug has so high impedance output so it really needs an amplifier and it comes with it so it forms a complete system. True, you really want a preamp close to the Covox for best results. I have not seen the adverts so I just don't know if it was ever advertised to be …

---

Re: CVX-2 : covox adapter

Posted on 2017-12-04, 21:33

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

But wasn't the Covox a complete system with amplified speaker, so shouldn't it be taken as a whole? I don't see why really. Many early sound cards were sold as complete kits with (cheap) speaker kits. I don't think anyone ever argued that the speakers need to be included for the overall quality of …

---

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 21:26

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Yeah, but has anyone tested to see what the actual cut off for the frequency range for the R-2-R covox is? Can it actually output a 22.05 KHz frequency? The Covox has no filter at all (and the CVX4 also has a no-filter setting). So theoretically there is no cutoff. I think the easiest way to verify …

---

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 21:13

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

I don't honestly remember the calculation, but given the design of the R-2-R covox I remember someone calculated that the frequency range for it topped out somewhere around 7 or 8 KHz. Are you sure you're not confusing the Covox with the DSS? The example recordings at 44.1 kHz with the CVX4 should …

---

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 19:18

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

Paralel wrote: It has roughly double the frequency range of the discreet R-2-R ladder Covox design What makes you say that? Technically, the only limit for the frequency range of a Covox is the speed at which the CPU can bang out the samples through the printer port.

---

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 18:29

by

by Scali

in Marvin \ Sound

in Marvin \ Sound

why not use Resistor Networks ? less pain to solder :) The goal of the CVX4 is to sound as good or better than the original Covox. I suppose we'd need to have some prototypes first with resistor networks, before we can decide whether or not they are an accurate replacement for the discrete …

---