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For comparison here is an original SWTPC MP-09 board.  By now SWTPC was using solder masks, but the quality was poor and solder would run under the solder mask The precision of the solder mask was poor and it was easy to bridge adjacent IC pads when hand soldering the board.  The SWTPC board is not silk-screened.


The MP-09B is a close reproduction of the SWTPC MP-09 SS-50 Processor board. There are only minimal changes to the layout.


Differences between the Original and Reproduction



The design of the MP-09 was not changed.  The reproduction incorporates the latest changes made by SWTPC that I was able to find. SWTPC boards often had jumper wires installed.  On the reproduction the jumper wiring changes were made to the PCB traces so no jumper wires would be needed.


The assembled board includes a modified S-BUG monitor.  It is currently marked V1.82 and includes a command to boot from the PT-SS30-IDE board


MP-09B Versions

The MP-09B can be ordered in several versions.  It can be ordered in both 1 MHZ and 2 MHZ clock speeds.  It can be ordered to support extended addressing.  When this option is selected the MC14411P is deleted. a 74S189 is installed at U8, and a few resistors are installed.  With the option to support extended addressing, you need a mother board that has baud rate generation on it.  For SWTPC that would be the MP-MB mother board.  There were other makers of MB's with baud rate generation as well.  Peripheral Technology makes the MP-B2R and MP-B3R mother boards that have baud rate generation on the motherboard.  There is probably little use for addressing >64K unless you are planning to run UNI-FLEX or OS9 Level 2.  At the time of this writing I have not been able to locate an L2 version of OS9 for the SWTPC system, although I see some references to it in a few places.  Until an SWTPC DMAF style of floppy controller is replicated, UniFlex is of no use since it requires a DMA floppy controller.  It won't run on a DC1, DC2,  DC3, DC4, FD2 or FD2A floppy controller.

Considerations for running at 2.0 MHZ

Although SWTPC released a few tech notes on running at 2.0 MHZ, they did not give a comprehensive guide on how to convert from 1.0 to 2.0 MHZ. In general you need memory boards with 250 ns memory, a floppy disk controller that will support a fast bus operation like the FD2 or FD2A. Serial cards need to have an MC68B50 chip. For IO cards it may be possible to select the slow IO setting, if your mother board has this option.

The configurations tested for running at 2.0 MHZ  contained these boards:  MP-B3, MP-B2R, MP-B2 modified for 16 address IO and 6809 addresses, Peripheral Technology MP-09B at 2.0MHZ, PT-SS50-64K memory board, a custom made board containing 2 512Kx8 70ns RAM chips, FD2, FD2A, a Digital Research 64K memory board with 6116's 200ns chips.  MP-S with MC68B50, Corsham Serial board with MC68B50 also are options.  Software can be an issue as some disk drivers didn't have enough delay after writing a command to a register.  After writing a command to the FDC, you have to wait a certain number of micro-seconds.  This was usually created by a software timing loop. If you have software with this problem, troubleshooting the system can be maddening. A few sectors can load properly and others don't load at all. It's not really apparent why the system is not working.  FLEX from SWTPC, assuming it is a later release, and OS9 will not have this problem. Don't forget that some early disks might not boot properly or at all in a 2.0 MHZ system because the boot code on the disk also contains the wrong software timing loop for 2.0MHZ.

Product Summary



Floppy Emulator

With good floppy drives hard to come by, to say nothing of blank diskettes, an alternative is needed.  A GoTek drive with Flash Floppy firmware update is capable of reading and writing disk formats as used by FLEX . The GoTek uses USB memory sticks to store images of floppy disks and can hold thousands of disk images on a single USB stick.  The images can be emailed as well as downloaded over the internet.

 This allows users to download DSK image files from the FLEX users group and with a newly released utility convert these image files to  .IMA format used by the modified GoTek unit.  The firmware is free and the software to reflash the GoTek is also free.  You will, however, need a special USB cable and a PC to reflash the firmware in the GoTek.  Once modified, future firmware upgrades can be installed from a USB stick.  For those not wishing to modify the GoTek, we will provide modified GoTek's ready to use, but these will be acquired and modified after you place your order and of course are not warranted since reflashing the firmware on the GoTek will void its warranty. You should consider the OLED modification mandatory, since it is almost impossible to tell which image file you have selected without it. The as delivered GoTek displays a number of the file image selected while the OLED displays the file as text.

The instructions for flashing the firmware and adding the OLED can be found here - https://github.com/keirf/FlashFloppy/wiki

You may use a real floppy drive with a GoTek should you have a need to read or write real diskettes.


Hardware manuals

MP_09B_AssemblyInstructions.pdf  Original SWTPC MP-09 instructions

MP_09_SchematicLeft.jpg  Original SWTPC Schematic - Left Half

MP_09_SchematicRight.jpg Original SWTPC Schematic - Right Half


SBUG1.82-PTIDE-F800-FFFF.BIN SBUG V1.82 with support for PT-IDE Controller

WDISK-SWTPC-E800-EFFF.BIN The hard disk drivers to be used with the above SBUG

Source Code

SBUG.ASM S-BUG 1.82 Source with IDE Boot command

WDISK.TXT IDE Driver Source

GoTek Images

FLEX291.IMA GoTek image,  SWTPC FLEX 2.91 BOOT DISK - NO IDE Support

Click Here  for Utility program to convert DSK to IMA format for GoTek

Software Manuals

FLEX 6809 Users Manual.pdf  FLEX 9 User's Manual

FLEX 6809 Advanced Programming Manual.PDF  You need this, if you want to write programs

ASMB6809.PDF FLEX 6809 assembler Manual


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Price List Hardware

MP-09B-1 MHZ Assembled and Tested 1 MHZ board - Includes S-BUG-1.82 - Specify for extended memory - deletes MC14411 $99
MP-09B-2 MHZ Assembled and Tested 2 MHZ board - Includes S-BUG-1.82 - Specify for extended memory - deletes MC14411 $119
Bare MP-09B Bare MP-09B Board - No Boot ROM $25
PT-SS50-64K 64K memory board - 120ns or faster, 56K usable for SWTPC/6809 systems $39
PT-SS30-IDE-32GB PT-SS30-IDE board, with SD memory to IDE adapter, 32GB memory card and FLEX preloaded and ready to boot. Includes a Boot ROM.  Cost is $55 (ROM deleted)  if ordered at the same time as an assembled MP-09 $60
GoTek GoTek modified with Flash Floppy firmware  and OLED display installed - Comes with USB stick with Boot FLEX image $60

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