Okay, so I'm almost two decades too late, but I've recently been playing around with Propellerhead's ReBirth RB-338 - a wonderful little acid machine emulator...
'ReBirth RB-338 is a software synthesizer for Microsoft Windows, Mac OS 8-9 and iOS for the iPhone, iPod Touch and iPad. It was developed by Propellerhead Software, and its first alpha version (for Mac OS) was publicly released in December 1996. Propellerhead Software ceased developing the original program in January 1999. Support for desktop versions was officially discontinued in September 2005. Shortly afterward, the ReBirth Museum Web site was launched and the last desktop version's (2.0.1) disk image was made available as a free download. Propellerhead Software continues to develop other software relating to dance-oriented computer-based music composition, including Reason, its flagship software synthesizer, as well as portable "app" versions of ReBirth.
'ReBirth emulates two Roland TB-303 synthesizers, a Roland TR-808, and a Roland TR-909 drum machine all at once. Each of the emulated devices has its own pattern selector, a feature the original devices are lacking. This allows fast switches between different musical sequences, and re-programming the TB-303 for playing different notes, for instance, is rendered unnecessary. This feature has been adopted in some of Reason's devices. ReBirth also features mixers, a pattern controlled filter (PCF) and some of the standard effects in software synthesizers like delay, compressor and distortion.
'The program also supports user modifications, which may replace the samples in the drum machine emulations and modify the GUI. There are four modifications included in the ReBirth installation by default (though the default ReBirth GUI seems to count as a modification as well).
'The virtual knobs and controls can be assigned to physical counterparts via MIDI, so knobs, modulation wheels, faders and other performance controls available on keyboards and modules can be used to shape the software sound.
'ReBirth was an early software synthesizer, pioneering this class of instruments along with Cubase, Cakewalk, Digital Performer, and Reality in the mid-1990s. The sound quality during live playback (as opposed to saving the generated sound to disk), assuming that the CPU could cope with the sampling rate, was imposed by the quality of the sound card.
'The software emulates two monophonic bass synthesizers with filters, two analog drum machines, effects, other filters, and patterns simultaneously, also processing and sending MIDI messages. This suggests highly optimized programming on Propellerhead's account, contrasting with extremely CPU - and soundcard - demanding modern soft synths and plug-ins.
'Some enthusiasts have criticized ReBirth's software emulation of the TB-303 as being an inferior copy of the genuine sound. Such criticism is common to many software synths that emulate analog synthesis (which the TB-303 featured), due to the reputedly inimitable sound of analog synthesis, and quality degraded by low-end sound cards. Despite this, Roland contacted Propellerhead Software to give it an unofficial thumbs up, which Propellerhead considered to be the Roland seal of approval.' (ReBirth Museum website & Pirate Bay torrent download).