[Coco] re; OS9 68K, MM/1 software and questions

Francis Swygert farna at att.net
Tue Dec 29 07:55:06 EST 2015

Part of the reason the MM/1 failed is that it wasn't really an upgrade path for the CoCo -- unless you were a staunch OS-9 user. Then it made some sense. It used a Signetics 68070 chip that had an integrated MMU and I2C bus. This reduced chip count and made the 32 bit processor compatible with cheaper 8 and 16 bit peripherals. The ship was a version of the 68000 or 68010, not a higher speed one like the 68020/40/60. It used some CoCo peripherals such as the joysticks, hi-res mouse, floppy drives (not controller) and serial printers, but that was about all. Oh, it was set up to use the CoCo3 RGB monitor as well... which hobbles it today as RGBA monitors are hard to find. If you had a SCSI hard drive you could reuse that too, but would have to dump all the CoCo OS-9 stuff. The high integration means it's not pin compatible with any other processor, and isn't upgradeable.

"Several solutions are being weighed that offer a level of RS-DOS(Disk Extended Color Basic) compatibility as well." Those never materialized. I think emulation was one of the options, but the 15 MHz processor just wasn't fast enough. 

It should run generic text based 68K software. Graphics may be a problem, as the video chip may not be supported by other systems. It uses a video chip made specifically for it, the Signetics 66470. The 68070/66470 combo was made specifically for Philips for CD-i machines. It was obviously available for use in other embedded systems, but I don't know of any full blown computer systems that used it other than the MM/1. OS-9 was used in most of the CD-i systems... you could even "root" the devices and get into the OS. 

This may help:Philips 68070 - Wikipedia, the free encyclopedia

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| Philips 68070 - Wikipedia, the free encyclopediaThe SCC68070 is a Philips Semiconductors-branded, Motorola 68000-based 16/32-bit processor produced under license. While marketed externally as a high-perfo... |
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Only the TC-9 from Frank Hogg Labs had some CoCo software compatibility, and that was limited. It ran OS-9 software, not DECB. The TC-70 had a 68070 processor as well, and integrated graphics and most necessary peripherals on-board also. Both used the K-buss backplane system. FHL also provided 68000 and 68040 boards you used with other video cards and peripheral boards, which made them a bit more expensive, but also more powerful and flexible. FHL alluded to DECB compatibility "from other vendors". Someone was supposedly working on an emulator for one of the faster 68K cards (I don't think the 070 board) and a plug-in card that was basically a CoCo on a card that used the K-buss for video and I/O. 

 Frank Swygert
 Fix-It-Frank Handyman Service

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