          Fact Sheet for SemiDisk DT42 Computer System

The  Deep Thought 42 single board computer from Semidisk  Systems 
is  the  best CP/M-compatible computer ever designed.   This  may 
sound like just another grandiose advertising claim, but look  at 
these features:

                            Hardware

The DT42 is a single board computer, sized 5.75" by 8", and  uses 
only +5V at 1 amp with a complete complement of chips.

     -  9.216  MHz Hitachi HD64180 cpu  gives  you  computational 
throughput beyond that of a 12 MHz Z80 machine.  And, unlike some 
other  9MHz 64180 designs on the market, this machine has no  RAM 
wait states to slow you down (one RAM wait state slows most other 
designs  by 30%).  12.288 MHz will also be supported when  faster 
64180 chips are available - this is better than a 16MHz Z80!

     - The board comes with a floppy drive interface design  that 
supports  4 5.25" 48tpi or 96tpi AND 4 8" single or double  sided 
floppy  disk  drives  simultaneously.  Eight  floppies  at  once!  
Additionally, the 1.2Mb 5.25" floppy drive models (such as  those 
used in the PC-AT) are also supported.

     - 512Kb RAM is standard, with 428k available as RAMdisk.  An 
optional  disk  emulator expansion card adds  8Mb  of  ultra-fast 
storage,  with optional battery back-up.  The awesome  processing 
speed of the DT42 combined with this large amount of RAMdisk will 
make you wonder what all the fuss regarding hard disks is about!

     - If you want a hard disk, the DT42 supports this also.   An 
included  on-board SASI port interfaces directly to popular  hard 
disk controllers made by Adaptec and Xebec to give you  megabytes 
of hard disk storage.

     - Communications facilities include 4 on-board serial  ports 
and  a  parallel  output  port.  Two  of  the  serial  ports  can 
accommodate speeds in excess of 300k bps; and the DT42  overcomes 
a shortcoming of 9MHz 64180 designs and allows you to run  serial 
ports  at  38,400 baud.  One of the serial ports connects  to  an 
optional on-board video display manager and keyboard  controller, 
so  no separate RS-232 terminal is required (although one can  be 
used if desired with no software changes).

     -  Optional  Dallas  Semiconductor  "Smartwatch"  real  time 
clock/calendar chip, and additional EPROM sockets are available.

                            Software

     - A special version of the advanced Z-System disk  operating 
system  is available with the DT42.  This includes ZCPR  3.3  and 
ZRDOS 2.0 and over 90 utility programs.  This version of Z-System 
(called  the "Hyperspace Z-System") places ZRDOS outside  of  the 
64k TPA space.  Z-System is modern software technology, packs  an 
incredible  amount  of  power and features,  and  will  give  you 
tremendous flexibility and convenience compared to CP/M or MSDOS.

     -  The  BIOS  of  the DT42 supports  the  large  amounts  of 
RAMdisk, hard disk, and floppy drives available.   Communications 
channels  are interrupt-driven; CP/M-compatible  logical  devices 
such as LST: and CON: are easily redirected; and the majority  of 
the BIOS resides outside of the 64k TPA space.

     - Because of the advanced characteristics of the  Hyperspace 
Z-System  and the BIOS, CP/M-compatible application programs  see 
57.5k bytes free memory, even with a full featured (5k  overhead) 
ZCPR3 implementation including IOP and RCP support.

     -   Very  powerful  BIOS-resident  disk  handling   software 
supports eight different floppy disk formats without any  special 
conversion  software.   You can directly read,  write,  and  copy 
between formats such as Kaypro, Osborne, 8" single density, etc.

     - Utility programs written for the DT42 include FVC, CONFIG, 
and  HDFORMAT.  FVC allows you to format, verify,  and  track-to-
track  copy the different floppy disk formats; CONFIG allows  you 
to customize elements of the system software such as  reassigning 
logical disks (eg, any physical device such as the RAMdisk  could 
be set as drive A:, drive B:, etc.), setting communications ports 
parameters  like  baud  rate etc.; HDFORMAT is  a  very  flexible 
SASI/SCSI  command editor that allows you to communicate  with  a 
SASI/SCSI device attached to the DT42.

     - The EPROM-resident DT42 Monitor allows you to examine  and 
modify  memory within the full 512k; auto-boots the Z-System  (if 
available)  when  the hardware is reset; and  contains  important 
debugging-style commands for setting breakpoints, tracing program 
execution,  and  uploading  code.  You  can  switch  between  the 
Monitor and Z-System at any time.

No other computer ever made possesses the raw power and  features 
of the DT42.  This machine is blindingly fast, and the Hyperspace 
Z-System represents a significant and positive new development in 
CP/M-compatible   computing.    Combined  with   standard   CP/M-
compatible  applications such as the forthcoming WordStar 4.0  or 
dBase  II,  Multiplan, Turbo Pascal, Turbo Modula-2,  etc.,  this 
machine will provide for your computing needs for years to come.

To find out more about the DT42, please call or write SemiDisk:

          SemiDisk Systems, Inc.
          11080 SW Allen Blvd.
          Beaverton, Oregon  97005  USA
          (503) 626-3104

Trademarks: DT42: SemiDisk; HD64180: Hitachi; Z80: Zilog;  PC-AT: 
IBM;  Smartwatch: Dallas Semiconductor; Z-System,  Hyperspace  Z-
System,  ZCPR3, ZCPR 3.3, ZRDOS, Turbo Modula-2: Echelon;  MSDOS, 
Multiplan: Microsoft; WordStar: Micropro; dBase II: CP/M: Digital 
Research; Ashton-Tate; Turbo Pascal: Borland International.
