Path: utzoo!utgpu!watmath!att!pacbell!lll-winken!csd4.milw.wisc.edu!jgreco
From: jgreco@csd4.milw.wisc.edu (Joe Greco)
Newsgroups: comp.sys.cbm
Subject: Re: Problems with 1764 and Ramdos 4.2
Keywords: C64  C128  Ramdos  no-workee  hep hep
Message-ID: <3714@csd4.milw.wisc.edu>
Date: 7 Aug 89 23:23:38 GMT
References: <13237@nuchat.UUCP>
Sender: news@csd4.milw.wisc.edu
Reply-To: jgreco@csd4.milw.wisc.edu (Joe Greco)
Organization: Starbase 74 - Starfleet Operational Support Services
Lines: 68

In comp.sys.cbm article <13237@nuchat.UUCP>, seven@nuchat.UUCP (David Paulsen) wrote:
]
]
]I have a rather perplexing problem with an old C64 and a new 1764
]ram expansion unit... 
]
]But first, a little background:  I'm using a 1764 on my C128, having
]upgraded the 1764 to 512K.. it works great.  Ramdos 4.2 has been living
]in my 128 for almost a year, running my bbs faithfully with nary a glitch.

No offense to the folks who wrote it, but 4.2 stinks.  It seems to
handle vectors very messily, and I can't get it to install on my
system (which requires altered vectors).  3.2 had no problems
whatsoever with vectoring...

]I liked this arrangement so much that I acquired a second 1764 for my
]ancient, dusty Commodore-64 (rev.2 board, I think.. circa 1983). I tested
]the new, un-enhanced 1764 on my 128; it worked fine.  Ramdos booted up
]and I could run a minimalist bbs just like old times.
]
]Problems arose when I plugged my 256K toy into the C64, however.  Ramdos
]booted okay, and copying files to the ramdisk SEEMED to work.. but after 
]awhile the ramdos directories became corrupt.
]
]Powering everything down, I tried again.. same results, but with different
]files in the directory getting nuked.  Lots of "" (double-quote) filenames
]with ??? filetypes.  Suspecting my copy of Ramdos to be the culprit, I 
]booted up the various demos that came on the 1764 utility disk.  Without
]exception, every demo flaked out with random garbage appearing in the
]middle of the animations.  Not good.  I was sure my 1764 had mysteriously
]fried itself when I plugged it in.  I immediately re-installed the unit
]on my 128, and it worked fine!
]
]What's up?  Is there something about my old 64 that's confusing the 1764?
]
]Note that in every test I was using one of the beefed up power supplies
]that come with the 1764 unit; I have two of these supplies.. they can't
]BOTH be flakey, can they?  In no case did the 64 ever crash; it was just
]reading/writing data to the REU in a helter-skelter fashion.
]
]Hep me!  Pleeze, somebody hep me!

Sounds like the fun I'm having, except I'm working with a 1700 and
1750.  The 1700 has decided it no longer wishes to work on a C64 (it
used to), but the 1750 works fine.  If I use the 1700, the BBS
complains that the expander is not holding data correctly (an
on-the-fly RAM test is performed as the system loads, and mild error
checking later).  The 1750 works fine, however.  The 1700 seems to
work about 95% of the time, but mangles every 20th or so record.

This is not good, I think I may have brain fried the thing trying to
get the two of them to work together.


An aside to Fred at Commodore....

Not being able to locate a 7407, I used a 74LS08 instead and
encountered identical problems to what I had when using a diode-based
AND gate (DMA line hack).  The circuit *works* with one expander.  But
now I find my 1700 not wanting to work.

What is the supposed "modification" needed to make the 17xx units work
on the C64?
--
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