Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!rutgers!lll-crg!seismo!gatech!gitpyr!jkg
From: jkg@gitpyr.UUCP
Newsgroups: comp.sys.att
Subject: Re: IBM-PC keyboard for 6300 has anyone done this?
Message-ID: <2735@gitpyr.gatech.EDU>
Date: Thu, 27-Nov-86 11:00:19 EST
Article-I.D.: gitpyr.2735
Posted: Thu Nov 27 11:00:19 1986
Date-Received: Fri, 28-Nov-86 07:06:50 EST
References: <1519@ihlpl.UUCP> <328@neoucom.UUCP>
Reply-To: jkg@gitpyr.UUCP (Jim Greenlee)
Organization: Georgia Institute of Technology
Lines: 29

In article <328@neoucom.UUCP> wtm@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

-- 
The Shadow...!{akgua,allegra,amd,hplabs,ihnp4,seismo,ut-ngp}!gatech!gitpyr!jkg

Jryy, abj lbh'ir tbar naq qbar vg! Whfg unq gb xrrc svqqyvat jvgu vg hagvy lbh
oebxr vg, qvqa'g lbh?!