This card provides 8-bit PCM/ADPCM + FM music (OPL2) + CD/Line + PC-Speaker playback via high quality low-noise audio path.Designed by LABS in Latvia
Please note that current PCBs are classic green What is it? BlasterBoard is an ISA sound card for PC or compatible retro systems running DOS and intended for vintage gaming enthusiasts. The card i...Read More…
BlasterBoard is an ISA sound card for PC or compatible retro systems running DOS and intended for vintage gaming enthusiasts. The card is software compatible with Sound Blaster 2.0 and has a high quality low-noise audio path.
My initial idea was to create a sound card using discrete off-the-shelf components to play some games from the past on my ancient 486 PC. I did not power up the machine since early 90s, it was just collecting dust at the attic. But after watching some retro gaming videos the nostalgic inspiration grew and I decided to give it a try. The machine was thoroughly cleaned, powered up and booted into MS-DOS perfectly. Some games were still installed on its hard drive, but there was a problem - the machine lacked a sound card. Buying one was not the way I wanted to go, but making one myself from scratch was a real dive into retro computing, so I got to work immediately.
The main goal was to make a low-noise device with simple architecture and features I actually needed, so my plan looked like this:
Clean and powerful line/headphone audio output
...and of cause high software compatibility with DOS games!
I followed Sound Blaster 2.0 compatibility for its widest support of DOS games and simple design. To make it even simpler I dropped useless sound recording ability and a gameport of the original card, but added PC-Speaker input and stereo CD/Line input, so the card could support any DOS game that produce any sound at all.
It took about a month of intensive work before I was able to hear a legible PCM sound coming from the speakers. Despite it was just a heap of breadboards and wires, the excitement of hearing an explosion sound of Duke 3D logo was over the top!
Two more months I was struggling with noise reduction, solving compatibility issues, prototyping and polishing software and hardware. And persistence did its job. Windows 98 finally detected the card automatically upon install and named it officially "Sound Blaster or compatible".
The final step was to make it a nice looking single PCB device.
At the end I came up with a neat sound card that answers the most DOS sound demands: CD audio, FM music, digital sound effects and PC-Speaker summed up using a high quality audio mixer to a single low-noise audio output. It can be connected to a nice sound system or headphones without introducing unwanted noise, which was so common for mass-produced sound cards from DOS era.
Internal stereo CD/Line input can be used as a high quality input for connecting any sound source you want and mixing it to the BlasterBoard's output. Audio output has -94dB RMS signal-to-noise ratio and its design allows to keep low noise output even in vintage systems with very old PSUs like mine.
Now I'm offering the result of my work as a limited run of fun-to-build DIY kits or a fully assembled and tested boards.
An assembled and fully tested card can also be ordered.
The card has been already tested by me and other users on a quite amount of systems with lots of DOS software, including games like Doom, Heretic, Hexen, Descent, Quake, Warcraft, Blood, Duke Nukem, System Shock, Full Throttle, Gabriel Knight, Dreamweb, Goblins, Dune, Command & Conquer, Sim City, Ultima series, TES: Arena and many more as well as music trackers and demos.
The card's digital circuit uses discreet 74HC-series logic ICs. 8-bit sample playback is handled by ATmega328P MCU and MCP4901 DAC. Sample rates from 4kHz up to 62.5kHz are supported as well as ADPCM sample playback. Genuine Yamaha YM3812 (OPL2) chip and its companion DAC Y3014B are responsible for FM music playback. Stereo CD/Line input uses noise cancellation circuit to reduce interference noise as much as possible. PC-Speaker input also uses noise filtering, so the final signal is clean even on maximum volume.
All above signals go to the onboard mixer and are adjustable individually using 4 dedicated volume knobs from the back plane. The mixer has an active 15kHz 4-pole Low-Pass filter on its main bus for high frequency noise cancellation.
The card output's idle noise level is around -94dB RMS even when all volume levels are set to max and connected to its respective sources.
Card's output is a standard stereo mini jack connector. All sound sources are mono except CD/Line and are split to stereo at the output as well. The output gives loud and clean signal which is above the line-level at its maximum and also handles direct headphones connection.
Hardware settings are selected using jumpers:
*It is possible to select IRQ for OPL2 chip. This option adds two extra hardware timers to a system. But since it was absent on the original SB card, it is not supported by any software I know. It is here mostly for custom experiments, so can be skipped during regular operation.
The card is intended to run perfectly on all PC or compatible retro systems. Please keep in mind, that on faster machines (Pentiums and up) it will behave as the original SB 2.0 - some known games that are not intended for such CPUs may have a distorted sound or no sound at all. However, BlasterBoard is more tolerant to faster machines than SB. Such picky titles as, for example, "Alone In The Dark" in DMA-mode or "Crystal" demo run perfectly on Pentium 166 MMX with BlasterBoard, but failed to run with the original SB 2.0 on the same machine.
I hope that BlasterBoard will find its place in your retro PC system and you will enjoy building and using it as I did during its development.
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