On 2012-01-09 17:53, Hoffmann-Vetter, Martin wrote: > Hello Garit, > >> 6508R2? From the MOS numbering scheme that should be a CPU. Any idea >> what it is exactly? > The 6508R2 along with the FDC chip 8723 and the ROM found between them constitutes the floppy subsystem - just like every other external CBM drive we know of - only with the difference that the DOS in its ROM is not CBM DOS as we know it from the external drives. The subsystem seems to resemble a traditional simple disk/floppy subsystem much more than any CBM diskdrive that I know of - and yet is has its own CPU for some unknown reason. > It's an 6502 with IO-Port (see 6510) and 256 Bytes RAM! Have a look at > http://en.wikipedia.org/wiki/MOS_Technology_6508 and > http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/6508.zip. > > This is the floppy controller CPU! > Exactly :-) It is worth adding that the 6508 - the has a programmable I/O mapped to the address $00 (DDR) and $01 (DPR) - just like the 6510 - the 6508 just has more IOs (8) where the 6510 only has 6 IOs Message was sent through the cbm-hackers mailing listReceived on 2012-01-09 21:00:11
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