seven@nuchat.UUCP (David Paulsen) (08/07/89)
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.
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!
David
--
David Paulsen ..uunet/nuchat/seven ||| The Curiosity Shop BBS, 713/488-7836
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Crazy Dave's Computer Emporium: "If we don't have it, we'll get you!"jgreco@csd4.milw.wisc.edu (Joe Greco) (08/08/89)
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? -- jgreco@csd4.milw.wisc.edu Joe Greco at FidoNet 1:154/200 USnail: 9905 W Montana Ave PunterNet Node 30 or 31 West Allis, WI 53227-3329 "These aren't anybody's opinions." Voice: 414/321-6184 Data: 414/321-9287 (Happy Hacker's BBS)