Creative Micro Systems
9639 Memory Management Processor

The Creative Micro Systems (CMS) 9639 was a high-performance 6809 processor card for the Motorola EXORbus. It was designed specifically to run Microware's OS-9/6809 Level II operating system with minimal overhead, to maximize performance.

CMS 9639 features:

• 2 MHz 68B09E processor
• MMU/DAT (Memory Management Unit with Dynamic Address Translation) uses a 2Kx8 SRAM to store 128 task maps, each with 16 4KB pages -- no need to ever update the mapping RAM on a task switch!
• 20-bit physical address for 1MB range (A19..A16 connected to memory boards via ribbon cable)
• 4 task registers (OS, User, DMA source, DMA destination)
• full 64KB (65536 bytes) RAM available for each user task
• SWI2 postbyte automatically saved in a register accessible to the operating system, and PC return address automatically incremented before being stacked, to speed up processing system calls
• 28-pin socket for 4KB or 8KB EPROM
• 2 serial ports (6551A) with RS-232 transceivers
• programmable timer module (68B40), with connector for external signals
• DMA controller (68B44)
• calendar/clock (MSM5832), with on-board battery backup
• 86-pin EXORciser BUS (EXORbus) card-edge connector (refer to Table 2-6 of the M6800 EXORciser User's Guide)

The CMS 9639 had similar capabilities as the SS-50 bus GMX 6809 CPU III from GIMIX. (I suspect it also had a similar high price -- one price list showed the GMX 6809 CPU III with OS-9-GMX III at U$1698.01 in 1984! Recently someone mentioned he has a "recreation of the cms9639/gimix CPU III" and is working on booting OS-9 Level II on it. I hope to get more information on this system.)

I don't remember who gave me a copy of the CMS 9639 documentation many years ago. Since it was a photocopy of a photocopy, some of the scanned image is unfortunately a bit difficult to read. Also, the logic in the three PAL chips (U22-PAL20L10, U23-PAL16L6, U32-PAL20L10) is not documented in this manual.

But I am in contact with someone who purchased a CMS 9639A board in 2019. Since these PAL chips are just combinatorial logic, not registered, it should be possible for him to eventually determine the logic by applying various combinations of inputs to each chip and monitoring the outputs, then using logic minimization algorithms (such as used by Logic Friday) to extract the logic.

If anyone has found an advertisement or press release for the 9639, or has a user manual or any other documentation for it, or an OS-9 boot disk, please contact me so I can update this page. (I did find a small black&white ad for it in Electronics Design magazine.)

Creative Micro Systems also sold many other boards for the EXORbus.

In 2019 I found someone who had used a CMS system in 1990. It ran OS-9 Level II, so most likely included a CMS 9639 CPU board. It also had 192KB RAM, 2 serial ports, a Wyse 50 terminal, an 80 track floppy disk drive, and a 10 MB hard drive. He told me he still has this system!! But it is in storage, and he hasn't yet found time to access it. I'm hoping he has user manuals for it that we can scan, and that maybe it still works, so we could extract the OS-9 boot file and system utilities.

The EPROM on the CMS 9639 was used to boot OS-9 Level II, and contains the "Boot" and "OS9p1" modules specific to this hardware configuration. The OS9p1 module includes the code that manipulates the DAT/MMU on the 9639. Two people have disassembled this ROM image:
 Eric's disassembly
 Søren's disassembly

In 2023 Eric was able to boot OS-9 Level II on his CMS 9639A! Since he didn't have a disk controller or hard drive for it, he removed the disk drive boot module from the EPROM and replaced it with a DriveWire boot module, so it could boot from the serial port: Eric's blog post

	CMS 9639 Rev B color photo. (653KB .jpg)
	CMS 9639 Rev A specifications and schematics (handwritten annotations are mine). (4.3MB PDF scanned image)
	CMS 9639 OS-9 Level II boot ROM image. (1 binary image, address map, 4KB .zip)
	Microware OS-9 Level Two System Designer's Guide (handwritten annotations are mine). (5.2MB PDF scanned image)

"OS-9" is a registered trademark of Microware LP.

Last revised 2025-Sep-22 14:15 PDT.
Copyright 2019- David C. Wiens.

---

 Home   Other 6809   Contact   Site map