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Emulator III : Technical Description
Architecture The Emulator III is a 16 voice, 16 bit, polyphonic digital sampling keyboard, which uses a National 32016 main CPU, clocked at 10MHz. The EIII is entirely controlled by computer software which is
loaded from disk when it is powered on. The EIII kept with the overall EII design, using a micro controller for sample access, a main CPU and a scanner CPU (Rockwell 6502 processor with 192 bytes of RAM! - as used in the Emax II).
The 32016 main processor and 32081 floating point coprocessor run the operating system from 128k bytes of DRAM in overlay mode (each module is loaded from disk when needed). The 32016 boots from two 27128 EEPROM's, this is the firmware
that can be seen loading on the LCD when the EIII is first powered up.
The F Chip To cut down on costs and to reduce the circuitry, E-mu Systems developed their own F chip to act as
a custom timer for each channel and a 2 x oversampler for the DAC.
Support Chips There is a floppy disk interface handled by a
WD1772 chip, with SCSI handled by a 5380 chip, and a 82530 for serial communications to MIDI and RS422.
Sample Memory The 4 or 8 MB of sample memory on the EIII consists of 16 x 256kbyte (150nS DRAM), 4 or 8 x 1 MB (120nS DRAM) fitted on the top circuit board. Memory prices had reduced
since the EII was manufactured (1024kbyte max.) but the costs are still unbelievable today, with 4 MB costing $1800 in 1988.
See the Upgrades section for memory expansion information.
Engineering Changes The Emulator III has had a number of minor
circuit board changes to address early problems with MIDI, SCSI and a revised mounting for the internal Hard Drive (to increase its isolation from the case - thereby improving its chance of survival in a shock).
Digital Converters The stereo ADC is a Sony 20018 (rather
surprising !) and the 16 voice DAC's are PCM53JGI's. Not your run of the mill Analog Devices in this one !
Analog Filters The EIII has 16 analog filters (a Curtis CEM3387) which combine a 3 pole low pass filter, a 4 pole low pass filter with Q, plus gain and pan VCA's. That adds up to a 7 pole analog filter ! They
sound very pleasant. The main 32016 CPU generates software envelopes for the filters and VCA's - they are therefore consistent and they can be fast.
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Diskettes The EIII uses DS/DD 3.5" diskettes. High quality DS/DD diskettes are recommended.
Do not try and use DS/HD diskettes, they may cause
problems later on. We recommend and use Imation DS/DD.
There is a difference between double density media and high density media, and they are NOT interchangable. High density
diskettes have different magnetic properties; a higher coercivity, requiring a higher write current from the disk drive.
Formatting HD media as DD is not a good idea; the media will be
too weakly magnetized, and your data may be completely unreadable or may fade away after a while. These problems are worse on 5.25" disks than on 3.5" disks because the difference in
coercivity is greater for 5.25" media, but they exist for both types of disk.
Digital Sampling The EIII samples at 16 bit resolution, and stores samples into memory (and disk) as 16 bits. The EIII makes
extensive use of TTL integrated circuits and CMOS memory with some custom chips produced by Emu, and some Programmable Logic Arrays (PAL's).
The large number of chips are held in a horizontal card frame of 5
large PCB's. The frame is isolated from shocks by flexible mounts on the main casing.
The EIII's can be tempremental (often requiring an annual service), and some of the connections to the PCB's can cause problems.
This is really a studio instrument which you should avoid gigging, not least due to the expense of anything going wrong. Parts are not cheap and servicing can be time consuming. Take care of this baby !
Hard Drive
The original Hard Drive in the EIII is a Seagate SCSI 5.25" ST251N, which has the following specifications:
- 43.1MB formatted capacity
- 3,280 tracks and 820 cylinders
- 4 heads and 2 discs
- 7.5 mbit/sec transfer rate (less than 1MB/sec)
- 3,600 RPM spindle speedI
- 40ms average access time
We can still obtain these disks at around $100-150, or have a look
on www.ebay.com. However we would recommend replacing it with a larger and quieter drive.
That Sound The EIII has an awesome frequency range and clarity. The filters are not as powerful as today's digital filters but
they add warmth and edge. The EIII is still a perfect sound design platform, although the outputs are not phase coherent.
Weaknesses The EIII aftertouch keyboard is rather sluggish, the
outputs are unbalanced, and the internal fans and hard disk are rather noisy. Other than that this is pure quality - EXCELLENT !
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