PC Speaker Driver Program
This repository contains the MS-DOS driver source code for my DIY ISA PC Speaker Driver card that you can find on the Microelectronics page on my site.
The program allows the control of the output relay, switches between amplified and non-amplified PC Speaker modes, and ajdusts the digital volume control in amplified PC Speaker mode.
Since this is a very small program, I chose to write it entirely in x86 assembly language. Besides execution speed, which is out of question anyway on such a simple program, the main benefit is that the output executable file is only around 2.5 Kb. And since I like optimized code, you get the idea. If I were to write this program in Pascal, only the runtime code would've been about twice the size of my entire assembled program.
In other words, I also wanted to de-rust my x86 assembly skills. Naturally I had a lot of fun programming this driver and I had to reference to Michael Abrash's book a few times. I read it in the past but a lot of sections wiped from my memory throughout time.
Given that I designed the PC Speaker Driver hardware as an 8-bit ISA card, it might be replicated by XT-class machine lovers out there. And these computers often have low storage space and low code execution speed. So I think an assembly program would be a better idea in this case.
I am using the PC Speaker Driver hardware and software with my 32-bit 80386DX ISA Single Board Microcomputer. Thus code execution speed is trivial in my case. Also I have plenty of solid-state storage attached to this machine.
I am releasing my work under the GNU General Public License v3.0 terms and conditions, for educational and documentation purposes.
The following lines are taken directly from the commandline help screen.
Usage is: spkd.com [-?|-h(elp)] [-a=300-31F] [-c=0-7] [-q]
Where:
-?|-h shows this screen
-a=XXX hexadecimal ISA card I/O address
-c=X decimal hardware command number
-q reduces text verbosity
Commands reference:
0 = output relay flip
1 = output relay on
2 = output relay off
3 = mode relay flip
4 = mode relay on
5 = mode relay off
6 = volume down
7 = volume up