Path: utzoo!mnetor!uunet!nuchat!seven
From: seven@nuchat.UUCP (David Paulsen)
Newsgroups: comp.sys.cbm
Subject: 1700/1750 RAM expansions
Message-ID: <465@nuchat.UUCP>
Date: 11 Dec 87 07:59:27 GMT
Organization: Public Access - Houston, Tx
Lines: 44
Keywords: ramdisk questions 1700 1750



I've got a 1700 RAM expansion, intended for the Commodore 128.  After goofing
around with it for a few months, I've accumulated some questions I'm having
trouble getting answers for:

1. Where can I obtain a disk emulator for the thing, so that I can SAVE and
LOAD files to/from RAM just like DOS?  I had the impression that a utility like
that would come on the disk; it's really the reason I got it in the first
place.   

2. I've heard that a 128K 1700 expansion cartridge can be upgraded to a 512K
1750 cartridge... true?  Difficult to do?

3. What chip is supposed to go in the "U18" location on the circuit board?
(Yes, I've already taken it apart!  Bye-bye warranty...)

4. Can more than one 1700/1750 be utilized at the same time, via a motherboard?
What does this do to the 128's power supply?

5. What's the difference between the 1700/1750 and the 1764, aside from the
new power supply?  I have already upgraded my old 64's p.s. to a huge mutha
9A regulated bench supply... does this mean I can just plug 'er in to the 64
without frying anything?

6. With the 1700 installed on a 128, I GO 64.  From 64 mode, the MMU doesn't
let me see any of the 128's memory beyond 1 64K page... can the REC, in the
1700, even in 64-mode, see the whole 128 memory map?

As far as "friendly" Ramdisk emulators, the kind that allow OPEN as well as
DLOAD and DSAVE, I've been working on one myself.  It utilizes the REC's swap
capabilities to switch out chunks of the 128's RAM so it appears to the o/s
that there's very little overhead to the ramdisk software.  My actual overhead
is a little over 300 bytes, allowing about 11K of "actual" ramdisk support
software to be swapped in as needed.  It even works with most interrupt-driven
utilities, as long as they put the vector back where they found it, or pass
it thru... other than that, it's totally transparent.

Anyone doing anything with their 1700/1750's?
 
-- 
David Paulsen            ...uunet.UU.NET!nuchat!seven

"Commodore VIC-20... the wonder computer of the 80's!"