JBM 61h is a PC speaker emulator. It emulates the way the PC speaker had to be programmed to emit complicated sounds:
Listen to it
This demo shows how this plugin sounds like. To program complex sounds you had to alter between two frequencies with the PC speaker giving the illusion of real sounds. You had no volume control what so ever to work with. You could program simple vibrato's and arpeggio's. And that was about what you could do.
Download the plugin
Here is the controls:
Main:
GL controls the glide time
Altered frequency parameters:
O controls the offset between the two different frequencies
ADSRL controls the altered pitch's envelope where L controls the level.
LFO:
DL controls the delay
SW controls the sweap
RT controls the rate
DP controls the depth
...I ran one with nearly the same specs (AT&T 80886...monitor is a 12"...still decorates my studio space 
) ran Voyetra Gold sequencer. Man... I still think of what that thing could do. It took quite a while to convince me that a Windows based system was worth the jump from DOS 
...but yeah: Good times! 
)
