IBM-PC keyboard for 6300 has anyone done this?

jkg at gitpyr.UUCP jkg at gitpyr.UUCP
Fri Nov 28 02:00:19 AEST 1986


In article <328 at neoucom.UUCP> wtm at neoucom.UUCP (Bill Mayhew) writes:
>We flamed the AT&T salesperson, who produced the AT&T memory
>expansion card to get it up to 512K.  I was suprised when I
>observed that the AT&T memroy card has to go in one of the slots
>that has the short socket near the front of the machine, although I
>don't see any reason why you couldn't use one of the expansion
>cards for regular pc-compatibles.

I'm going to try to atone for my earlier faux pas concerning soldered-in chips 
by posting something useful. Can I be right just this once? Please? :-)

The reason the expanded memory card uses the little slot is because the 6300
has an 8086, which requires 16-bit wide memory. The standard PC-compatible
slots only support an 8-bit bus, so the additional 8 data lines (among other 
things) are brought out on the other slot.

I think this also effectively halves your memory bandwidth because the bus 
only runs at 4 MHz. All memory accesses to the expansion memory will require
the insertion of wait states to slow things down. Accesses to memory on the
motherboard can be run at the full 8 MHz with no wait states. This is one 
reason why it is preferrable to put the full 640K on the motherboard.

                                              Jim Greenlee

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