6151 RT Desktop
6150 Rear View


6151 RT Desktop

Slot 5 AT-Coprocessor slot
   The IBM RT 6150 and 6151 system units use ISA (AT) style I/O slots, however slot 5 on the 6151 and slot 8 on the 6150 are unique to the RT. Most cards that do not use memory refresh, or DMA channel 7 will have no problem with that slot.  Bus timings for all the RT bus slots may be slightly different from an AT, as I/O accesses are not driven by the processor directly, but are routed via a special bus processor in the planar, called the IOCC. 

   The 8th slot in the 6150 RT (5th slot for 6150 only)  have three signals different from the normal PC/AT assignments.

 Pin    Standard     CO-proc slot usage    My notes.. 
 B19    REFRESH      + SPK DRV             (Wire or'd to speaker control)
 D14    DACK 7       - DACK 8              DMA channel is reassigned..
 D15    DRQ 7        + DRQ 8                 .. ditto

- The PC XT mono/printer adapter, is ONLY supported in slot 3 in the 6150 tower, or ONLY in slot 1 in the 6151 desktop. [ I'm not sure why this slot 3 restriction is here, what's wrong with slot 6?  Timing? - MW ]

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