Hi Ruud, On 2011-10-28 12:29, Baltissen, GJPAA (Ruud) wrote: > >> From that I'll dare to conclude that the CBM-900 floppy disks are > DS/QD/100 TPI. > > How is this dive connected to the motherboard? If it was a 1.2 MB HD > drive, it would be connected to the MB by the wellknown 34-wire > flatcable. How about this drive? > Well that is a long story - that may give you some "new" part number to add to your partnumber list :-) You are right the drive has no well-know 34-wire flatcable connection nor does it have any shugart standard interface. As you propably know the drive is only mechanics - no amplifier circuitry or anything what so ever. The only thing coming out of the drive are something like eight or ten wires. Basically it is a stepper, a spindle motor, two disk heads and some sensors with wires attached to. The wire lead to a little converter PCB that is hanging dangerously close to the power supply and lots of other metal stuff - without any insulation. Anyway - out of this converter PCB comes a 20-wire flatcable - not 34-wire - there is no electronics on the converter PCB. The flatcable is connected to the main board. Another similar looking 20-pin connector is found in the same area of the main board - unpopulated - except for two attached wires that drives a chassis fan :-) Just besides the floppy connectors are some discrete (amplifier ?) components and now for the fun part... Just besides an EPROM labeled "Z8000 Fl. Cont. S41 6-20-85".... There is a MOS 6508R2-S CPU in cheramic package (09/85) and a MOS 8723R1 in cheramic package (22/85) From what I can find MOS 8723 is a floppy controller. The EPROM, MOS 6508, MOS 8723 and some other nearby discrete components on the mainboard seems to constitute a separate floppy controller just as the external CBM drives are made. Only I've never seen a 6508 in any CBM drives - usually 2x6502, 6504 and other 650x'es etc... MOS 6508 is a 6502 with enhanced io port and 256 bytes internal sram. More funny details: The MOS 8723 has the word "gut" hand written on it - meaning "good" in german. Some other place on the mainboard a MOS 8716R1 (cheramic - no mfg M/Y) it has the word "good" hand written on it. :-) The MOS 8716R1 is a DMA controller. I'll put up some photos some day - I just need to get a little further in the process. /Uffe Message was sent through the cbm-hackers mailing listReceived on 2011-10-28 23:00:26
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