Re: boot problem on Apple iic

[Carlo Porst <c.porst@bremerhaven-net.de>]

Matthias S�llner wrote:

> I have here two Apple iic computers. The first one works fine. The other
> doesn't boot from
> disk. The diskdrive begins to run, but the sound is not as strong as the
> working one.
> Then the error "Check Disk Drive" occurs. So i changed the two
> diskdrives. The good one ran with
> both drives. The bad one with none of them. So I suggest the error is
> not in the drive.
> The logic board of the bad one looks good. There's no visible damage. So
> I have two questions:
>
> - Is ist possible the error is in the Powersupply ?
> I thought of it because the Sound of the disk drive is a different, not
> so loud at all.
>
> - Or is it possible that some bits in the boot-rom have changed?
>
> - What else can it be?
>
> thanks for every reply
>
> Matthias

Hello Matthias,
regarding the rom you can do the following:
After powering on the IIc, press control-reset,
you will then be able to enter some basic commands.
Type:   Print Peek (64447)   to determine your Rom version.

255 = old IIc
0     = 3,5 drives can be used
3     = 3,5 drives + memory extension connector
4     = ???

If you have equal roms, you may change them.

On 255 rom-based machines typing PR#7 will boot an external drive.

The IIc has a built-in self test. Press OpenApple-CloseApple-Control-Reset.

On 255 based machines the test runs continuously (not sure). You will see
shifting
and inverting pixels on the screen and hear some tickles from the speaker.
On 0 based machines after completing the test, there will normally some
beeping
and a message on the screen: System OK.
I don't know what is tested by this procedure, perhaps somebody else could
help.

By the way, I have the same problem regarding disk access on a 0 rombased
IIc.
My idea is to transmit some test code from Apple Diagnostics V 2.1
via the serial port. Perhaps someone has done this and can help.

Carlo