Path: utzoo!utgpu!attcan!uunet!tektronix!percival!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: ramdrive above 640K limit
Keywords: ramdrive
Message-ID: <1212@bucket.UUCP>
Date: 14 Jan 89 09:14:28 GMT
References: <4616@sfsup.UUCP>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 28

In article <4616@sfsup.UUCP> aab@sfsup.UUCP (A.Bellotti) writes:
<
<I have a 6386WGS computer with 1Mbyte of Ram Running DOS
<3.3. Is there any way to use the memory between the 640K
<and 1M limit as a Ram Drive.
<
<I tried using the /E option for vdisk, but it seems to
<work for memory above the 1M limit only.

The reason you can't do it is because there *isn't* any system RAM
between 640k and 1 meg! System RAM is between 0 and 640K after that
the address space is reserved for display adapters and various ROMs

If your AT has 1 meg of memory, the most common motherboard setup allows
two setups. 512k of normal RAM and 512k of extended RAM (RAM addressed
above 1 meg), or 640K of normal RAM and the remaining 384k is ignored.
Some motherboards allow mapping as 640k normal and 384k extended, but
if you add more memory you have to go back to the 512/512 setup or have
a "hole" in your extended RAM.

A few motherboards (Compaq, for one) have some extra chips to fill the
512k to 640k gap, otherwise you are stuck with buying a board that will
let you "backfill" this space...
-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I used to be a hacker. Now I'm a 'microcomputer specialist'.
You know... I'd rather be a hacker."