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Shadow Lord
March 29th, 2012, 04:30 PM
Hello All,

First time posting in this area. While I am familiar with PCs and Macs, CP/M was well before my time. I've looked at IBM's CP/M 86 VERY briefly and picked up a CP/M book (Thanks Erik) just so I can get to learn more about the predecessor for PC-DOS. My interest has been historical and curiosity more than anything else. However, recently on a purchase of a lot I got a strange board marked as Deep Thought 42 (obvious Douglas Adams reference there) which made me very curious.

A bit of googling and I found out that it is a CP/M machine (a very good one from the sound of it) made by Semidisk. However, there doesn't seem to be much to go on and the board itself doesn't provide to many clues to a novice like me. I was wondering if anyone has any familiarity with this computer and/or has more solid info? I wouldn't mind getting a full fledged CP/M machine up and running in my vintage collection! TIA!

Shadow Lord
April 11th, 2012, 08:04 PM
Wow, nobody has even heard of this system?

Okay, well ground zero it is. I guess the first thing to do is to determine if I have a complete system or not. Let me explain: I have what appears to be a motherboard w/ a Z80 chip on it. Now, I know computers were sold as kits back in the day so is this what you got if you bought a DT42? And then were you responsible for providing your own case, etc.? Or do I just have a part and the system was sold as a a whole system.

kyeakel
April 12th, 2012, 06:32 AM
Found a bit of a description on gaby.de that says there was also a support board with memory and I/O on it. Look for Z-news 502, in any regard it sounded pretty advanced for the time. It does not indicate that there was a system config. Can you post some pictures?
Kipp

Shadow Lord
April 12th, 2012, 07:12 AM
Thanks for that bit of info. Actually all the info I have on the machine comes from Z-news. From what I gather it did not do so well in the market place. I will definitely post some pictures over the weekend.

barythrin
April 12th, 2012, 09:57 AM
There are a lot of references to a "deep thought" chess computer, but not sure that is related. I'm thinking it's newer than what you're seeing.

krebizfan
April 12th, 2012, 11:16 AM
I have seen a few things about the Deep Thought but mostly marketing material that made me wonder why such a wonderfully odd machine was being released in the mid-80s. I hope you can find the customised disks for it. Without working drivers for both disk controllers and the RAM disk, Deep Thought is rather blah. On the other hand, having the ability to attach 8 floppy drives plus SASI hard drives sounds useful.

Shadow Lord
April 12th, 2012, 11:51 AM
I have seen a few things about the Deep Thought but mostly marketing material that made me wonder why such a wonderfully odd machine was being released in the mid-80s. I hope you can find the customised disks for it. Without working drivers for both disk controllers and the RAM disk, Deep Thought is rather blah. On the other hand, having the ability to attach 8 floppy drives plus SASI hard drives sounds useful.

Yeah, it was an advanced machine but at the same time it was behind the times. I am not an expert by any means but it seems to me that CP/M was pretty much dead or dying by mid 80s. This would have been a killer machine in the early 80s but by then the PC was firmly entrenched. However, I still find it fascinating and would at least like to get it to boot up! In case any one is interested here is the "fact/spec" sheet on the machine:


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.


Shadow Lord
April 12th, 2012, 11:58 AM
Found a bit of a description on gaby.de that says there was also a support board with memory and I/O on it. Look for Z-news 502, in any regard it sounded pretty advanced for the time. It does not indicate that there was a system config. Can you post some pictures?
Kipp

I am trying to find this particular issue as the other stuff I've read (including the fact sheet) I just posted point to it being a single board computer. So I am working on that assumption (anything else would mean I have a non-working system so not much point there ;)) the board I have can be powered up and made to work. Now, having said that it is apparent that you could expand the system (not sure exactly how the other boards would connect perhaps directly at the HDD port) w/ at least a SemiDisk RAM Drive but nonetheless the system board should work independent of those.

Shadow Lord
April 12th, 2012, 12:29 PM
Here is the announcement (http://www.retroarchive.org/docs/magazines/z-letter/z-letter-no4.pdf) of end of production by August, 1989.

RickNel
April 13th, 2012, 04:03 PM
It's odd that boards like this claim to be "Single Board" when it it clearly a S-100 Bus machine that can't fulfil its promise without additional cards.

For example, the "SemiDisk" that gives it its name seems to be a separate battery-backed RAM card. There has been some new old stock of Salota RAM/EPROM cards advertised recently, which might be usable to reconstruct the SemiDisk. But you would need the S-100 bus motherboard, chassis and PSU I think.

Rick

rick

Shadow Lord
April 13th, 2012, 05:11 PM
It's odd that boards like this claim to be "Single Board" when it it clearly a S-100 Bus machine that can't fulfil its promise without additional cards.

For example, the "SemiDisk" that gives it its name seems to be a separate battery-backed RAM card. There has been some new old stock of Salota RAM/EPROM cards advertised recently, which might be usable to reconstruct the SemiDisk. But you would need the S-100 bus motherboard, chassis and PSU I think.

Rick

rick

Actually SemiDisk is the corporate name of the DT42 manufacturer. It is a bit confusing because the company initially started making battery backed RAM disks and selling them under the SemiDisk brand. These boards were originally intended for the S100 (http://www.s100computers.com/Hardware%20Folder/SemiDisk/History/History.htm) bus but SemiDisk was quite active in the PC arena (http://books.google.com/books?id=_Bg1jlRSiQMC&lpg=PA246&ots=lfmVq4ISFt&dq=semidisk%20corporation&pg=PA246#v=onepage&q&f=true)as well making ISA bus boards w/ battery backup (http://books.google.com/books?id=ey4EAAAAMBAJ&lpg=PA83&vq=semidisk&pg=PA83#v=onepage&q&f=true).

The spec sheet I posted above is genuine as far as I know. I.E. it isn't some reseller's/eBay BS but the actual fact/press release from SemiDisk.

Shadow Lord
April 14th, 2012, 01:36 PM
Good News/Bad News:

Bad News:

After a closer look at the board it looks as if it may have been picked clean. I see alot of free IC sockets and all the RAM chips seems to be missing. So this maybe dead in the water until more info surfaces.

Good News:

There is still vintage computer pr0n ;)

Full Frontal:

http://i375.photobucket.com/albums/oo197/TheRealShadowLord/Computer%20Collection/Misc/Deep%20Thought%2042/2d9d5f68.jpg

Rear View:

http://i375.photobucket.com/albums/oo197/TheRealShadowLord/Computer%20Collection/Misc/Deep%20Thought%2042/41f128f6.jpg

A peak at the particulars:

http://i375.photobucket.com/albums/oo197/TheRealShadowLord/Computer%20Collection/Misc/Deep%20Thought%2042/d081d38e.jpg

http://i375.photobucket.com/albums/oo197/TheRealShadowLord/Computer%20Collection/Misc/Deep%20Thought%2042/f888691a.jpg

RickNel
April 14th, 2012, 04:08 PM
You're right - it is a true SBC. I should have checked the specs more carefully before posting :( .

Hope you can find documentation - this board is in good shape. Apart from the RAM, it looks like all the main I/O driver chips are missing. One of the top right sockets might be EPROM? Far left probably line buffers for the FDD?

Smarter people than me could probably take reasonable guesses at what the other main missing chips are, based on the visible traces and locations.

Rick