View Full Version : SWTPC S/09 Questions

October 24th, 2017, 06:42 PM
I recently picked up this beauty. It appears to have a DC-4 Controller Card installed. Which drives support this? According to the documentation on Michael Holley's fantastic site, it was made for a 5.25" drive. Would the 8" drives made by SWTPC work, too? Also, the model number is "S00" instead of "S/09". It is clearly an S/09 though with the MP-MB motherboard and the MP-09B processor card installed.


October 25th, 2017, 01:09 AM
SWTPC never made drives, they just put OEM drives from other makers in boxes. From what I remember if you use 8" drives you need to run the controller chip at 2Mhz rather than 1Mhz. Not sure if the data separator would also work with an 8" drive... So certainly not without modifications. I also note that the SWTPC 8" drive system came with its own controller card...

October 25th, 2017, 07:50 AM
According to the information found here (http://www.swtpc.com/mholley/DC_4/DC4_Index.htm), it was made for the The SWTPC minifloppy disk unit. I was a bit confused because that drive was made back in 1977. I guess that must be it.

Thanks for the information.

October 25th, 2017, 08:49 AM
You can also use 3.5" diskettes...


October 25th, 2017, 11:11 AM
I recently picked up this beauty.

Do you have further pics on your site? I always find these machines interesting. Mine has a Percom floppy controller and two Tandy 5.25" disk drives. Pics are here (http://vintagecomputer.ca/swtpc-6800-a-great-collection-of-that-era/) if you'd like to see this floppy controller.

October 26th, 2017, 05:33 AM
The DMF2 was the/one of the floppy controllers that used 8" drives, while the DC4 and Michael Holley's DC5 used 5.25" drives. I believe the DC5 is based on the DC4. I think Michael has nearly all of the manuals on his site but I have the gold binders for both the 6800 and 6809 series machines if it would be of any help. I also have the SWTPc 5.25" drives/enclosure.

The S/09 is a bit later machine, coming from about 1980 or 81 and SWTPc's models can be confusing. There were also 69/A and 69/K model machines in the 6809 series.


October 27th, 2017, 04:22 PM
I just so happen to have a DMF2, so I just need to hook up my 8" drive. I used to have some terminals, but I sold them awhile ago. If I want to hook up a serial connection to my laptop using an application like HyperTerminal, what are the wiring instructions for that sort of serial cable? Can I buy it somewhere? Thanks!


October 27th, 2017, 09:11 PM
Nice looking system...really clean. With my S/09 I used Michael's DC5 with a generic 525" floppy drive in an external case, even though I have the DMF2. I believe the CPU board has SBug=E and I ran it with Flex using just a standard serial terminal. I do have the users manual for the DMF-2 board.


October 28th, 2017, 08:39 AM
It looks like it is RS-232C compliant. That makes things easy. Mine is operating at 1MHz based on the crystal. What is yours? The dates correspond to your estimate of 1980-81 construction.

October 30th, 2017, 06:43 PM
SWTPc 6800/6809 is not S-100. Matters because people searching for SWTPc in the future may miss this post and the info contained therein.

Here is the serial card connector pinout for RS232, assuming you have an MP-S card.


October 31st, 2017, 01:55 PM
It is an MP-S2 card (1979), specifically designed for the S/09. Does that make a difference for the pinouts?

October 31st, 2017, 02:48 PM
You should look it up, The MP-S is one of the first serial cards and made just as much for teletype as RS232. the MP-S2 is more for RS232 only and probably has at least one more line to manage.

October 31st, 2017, 02:58 PM
Its standard RS232. Info is here..


"Assembly Instructions" also has how to use and port pin-outs...

October 31st, 2017, 06:47 PM
Things were so much simpler with just ground, send and receive. :) Although this is more complex, it is still pretty straightforward. Hopefully, I can build it soon and test it. Thanks!