CBM 220 interior; Was: Secret Weapons of Commodore 13th edition

From: Marko Mäkelä (msmakela_at_gmail.com)
Date: 2007-07-07 21:56:26

On Fri, Jul 06, 2007 at 12:15:35AM +0200, Anders Carlsson wrote:
> Although the keyboards are detachable, yours is with black keys and
> his with white ones. Your unit also looks a bit more weathered. :-)
> See how his white keyboard is localized with Swedish/Finnish letters
> ÅÄÖ (*). As the entries for CBM 200, 210, 220 on Jim Brain's list once
> were added by Ville Muikkula, it suggests to me that this sub-series
> of PETs may have been exclusive to Scandinavia or even Finland.

I originally saw question marks in place of the non-ASCII characters.
That was your message headers misidentified the character set as ASCII,
instead of ISO 8859-1.  This message should be properly identified as
ISO 8859-1.

Hmm, I wonder if the 200 series model numbering was invented at PCI-Data
in Finland.  After all, they probably did the localization.  I don't
remember seeing any ads for PET computers, but at that time my only
computer news source was MikroBITTI, which was (and still is) home-oriented.

I just opened up the 220.  I can see three circuit boards: the
motherboard at the bottom, and two drive boards on the top part of the
case.  There are two 24-pin EPROMs with dot-matrix-printed labels on the main
circuit board: "CBM 200 SKAND.GEN 901447-14" at UC5, and "CBM 8296D
SKAKERNAL UE8" at UE8.  UE9 and UE10 are empty 24-pin sockets.  UE7 contains
a 28-pin ROM, "324746-01 ©1983 CBM 2584 TAIWAN 26011B-632".  UE5 and UE6
contain 28-pin chips, MOS 8700-008 and MOS 8700-009 (PLAs?) UE6 is socketed.

The motherboard is identified as follows:

80/40 COLUMN CPU 64/128K
ASSY NO. 324645    REV.B

The main board contains pads for some power supply parts, but they are
not mounted.  There is a heavy-duty power supply in a metal cage with a
11-watt fan (or 13-watt, it says both) on the back left corner, blowing

There are two banks of unsocketed 8 RAM chips.  UA1..UA8 contain
Hitachi HM4864P-3, and UB1..UB8 contain MOSTEK MK4564N-15.  I wonder if
all boards were fitted with 64 kilobytes (the Hitachi chips), and some
were fitted with the second 64-kilobyte bank afterwards?

The drive logic board 251120-01 REV.A has a daughterboard "251457 Ind.B" that
contains a 901885-04 (6532?), a 74LS04 and an EPROM labeled 251474-01B.

The drive analog board is 251121 REV.B.  Actually the original circuit
board was broken in two halves (!), and the replacement is from Ruud.
The original is 251121 REV.B as well.

So, I guess we can be sure that this 220 is a 8296-D.  That's also what the
back label says.  Serial number WG 2802.

If you insist, I can take pictures in daylight.  After all, the machine
was easy to take apart, because a previous owner has lost the case screws.

> (*) Yes, I know Å is only used in a few loan words and among Swedish
> speaking Finns, but it is off-topic.

Hmm, care to mention a loan word that contains å in Finnish? :-)  I can
only think of proper names, such as Ångström (10^-10 meters).


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