[comp.sys.ibm.pc] Info. needed about DMA controllers

johne@hpvcla.HP.COM (John Eaton) (10/14/88)

<<<<
< I have been unable to locate an 8237A-2 (8MHz). Most data books
< (AMD, INTEL, NEC, etc.) indicate that the 8237A-5 is the fastest
< version made. 
----------
Harris makes a CMOS 82C37A that runs up to 8 Mhz. It was listed in their
1986 data book. I would check the clock pin of the chip before investing
any money since it may not be operated at 8 mhz in your machine. They 
might run the DMA at 4.77Mhz normal and 4Mhz turbo in order to keep the
chip within specs. If you run a 8237 above 6Mhz then the pulse width of
the DACK* signal in verify mode is to short for a standard 765 Floppy
controller. 


John Eaton
!hpvcla!johne