Apple II

Apple IIe RAM problems...but I don't think the chip is the culprit

Submitted by Dr. Webster on October 7, 2020 - 4:36pm

I'm trying to fix a memory problem in a IIe. The self-test reports one chip is bad with the message:

RAM 0 0 0 0 0 0 1 0

So I desoldered the chip in position 12 (second from the right in the row of RAM chips) and installed a socket. Continuity between the socket and where the traces lead (ground or the pins of other RAM chips) looks good.

The RAM chip I removed was an MT 4264-15. I bought some replacements off of eBay and installed one in the socket (with the notch in the correct orientation). The self-test reports the same error.

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Apple II

Switching Apple III mainboard from 12v to 5v

Submitted by Verault on October 6, 2020 - 10:15pm

So i found this document that talks sbout the different IC's needed to convert a 12v apple III system bosrd to the 5v system :  https://www.apple3.org/Documents/Technotes/TA31049.html

 

I have an apple III system board i repaired by using a 12v memory board from another working system. I do have a spare working 256kb 5v ram board so i have to convert the system board over to use the 5v 256kb rsm. Where can i find these roms? Has anyone done this change before? Need info on this. Thanks guys.

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Apple II

" Apple é° " showing-up on boot of an Italian version of un-enhanced Apple IIe

Submitted by melamilano on October 3, 2020 - 11:02am

Hi everybody,

I recently got on the local Italian eBay a used Apple IIe (with an Apple Monitor III monitor and 2 floppy drives) because I want to enter for the first time in the magic world of this fascinating machine (the first computer my father gave me was a Commodore 64 in 1983: I was a boy, and I still remember I was looking with envy my richer friend's Apple II - it was too expensive for my family).

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Apple II

Liron card and unidisk 3.5 drives wont boot.. But it is it supposed to?

Submitted by Verault on October 2, 2020 - 4:58pm

So I just got my first Liron / Apple 3.5" floppy controller card. As soon as i put the card in the system (slot 6 or 7) I was expecting it to behave like a 5.25" floppy drive and attempt a boot from the 3.5" drive. But the Card doesnt even register in the computer the way the 5.25" floppy contoller does. The 5.25" controller at boot will show the Apple ][ at the top of the screen and attempt a boot or stay there. With the Liron card installed the computer always boots to a Basic Prompt. I can type in PR#6 and it will then attempt to boot the disk in the 3.5" drive.

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Apple II

Apple /// and /// Plus rgb and composite video questions

Submitted by Verault on October 2, 2020 - 4:53pm

I'm trying to find specific information about the Apple /// and /// plus video outs.  Alot of sites claim the composite output of the Apple /// is monochrome. I only own an Apple /// Plus and my composite video out seems to be in color.

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Apple II

Apple II revisions

Submitted by mmphosis on October 2, 2020 - 4:33pm

Does anyone has a revision list  for the Apple II?  A list with descriptions of the revisions would be great.  How many revisions were there?  How do I tell what rev my Apple II is?

 

I read a posting about 8-bit fonts, and was confused as to what these revisions were.  The bit about rev 7 and lower-case letters I have not heard of before - it doesn't sound correct to me:

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Apple II

Apple /// Datanetics keyboard

Submitted by Daniel Beardsmore on October 1, 2020 - 7:10pm

I learned with fascination some time ago that the Apple /// had both Datanetics DC-50 and Alps keyboards. Both took the peculiar route of having double-action arrow keys.I’m in contact with Meryl Miller from Datanetics, but he left the organisation before the Apple /// was created, and none of the Datanetics literature he preserved mentions double-action as existing. Curiously, the Datanetics double-action type has no “dash number” (DC-51-xx) which makes me wonder if it was created specifically for Apple and never advertised.

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Apple II

Strange Apple II keyboard types

Submitted by Daniel Beardsmore on October 1, 2020 - 7:02pm

Edward Harro Walsh documented on his website (currently suspended) some very bizarre keyboard switches reportedly found in Apple II computers. The only switch type depicted with photographs was the Alps type¹ — all the rest were shown with diagrams. The keyswitch types used in Apple II computers are fairly well understood: Datanetics DC-50, Alps KBB¹, ITT snap-action array (possibly Datanetics DC-70), SMK J-M0404 series, Mitsumi KAM, Apple hairpin spring and Alps KCM.

¹ normally KCC at this point in time, but inexplicably referred to as “KBB” by Apple in their bill of materials

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Apple II

Replacing an MMU (344-0010-B)

Submitted by gareth_IIe on October 1, 2020 - 10:47am

I need to replace the MMU (part number 344-0010-B) on an Apple ][e.  Does anyone know of anywhere I can buy one?  Alternatively, does anyone know if it is possible to burn some kind of blank logic IC in order to reproduce an MMU?

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Apple II

Disk Drive Apple //c

Submitted by pcbastler on September 30, 2020 - 1:37am

Hi,

 

I have a problem with my //c: It mostly shows the message "Check Diskdrive" when trying to boot.

After swapping the ROM FF with a ROM04 Eprom this behaviour changed and the //c work some better. But after inserting a "special" disk from my collection, the //c got back to the above behaviour. Even if the disks where written the same day on this //c. The disks are working properly on my ][ europlus.

 

I have already tried to clean the drive, but with no change. Seldom it reads the disks, so I am guessing it is not a completly hopeless case.

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Apple II

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