On 3 September 2015 at 10:15, John Robertson wrote:
> Some of the early ROMs had extra voltages and unusual select logic and for
> those you either need to make an adapter or get an ancient Eprom programmer
> to be able to read them.
>
> I use Data I/O 29B with a Unipak for most of my old timers,
While I was trying to read the ROM in my 9121 for Eric Smith I found
out that my Wellon VP-280 could not do it (it could not recognize it
and only read FF FF FF FF). I could use it however to dump the ROM of
an IBM PS2 that I cannot boot anymore (so it is not entirely useless).
So I am asking what
Hi Eric,
I have a 9121 HP-IB disk drive I can try to extract the ROM from
(using an old EEPROM programmer I have).
Regards,
Vlad.
On 2 September 2015 at 00:38, Eric Smith wrote:
> If anyone has dumped the ROMs from the HP 9895 (8-inch) or 82901/82902
> (5 1/4-inch) HP-IB disk drives, which use
On Sep 1, 2015, at 1:57 PM, tony duell wrote:
>>
>> Hmm, you are right, I am not seeing any spikes in voltage there. On
>> the collector of the TR23 all I am getting as DC voltage is around
>> 110mV. The oscilloscope tells me I am getting Vpp of about 4.4V with
>> Vmax at 2.6V and Vmin at -1.8
On 1 September 2015 at 10:59, tony duell wrote:
>
>
> What do you see on the collector of TR23, which should be a small power
> transitor (TO220 package I think). If it's working properly there would be
> some
> very high voltage spikes (kV) there, but under these conditions probably not.
> What
On 1 September 2015 at 00:54, tony duell wrote:
>
>> Hi,
>>
>> I traced the 18Khz signal all the way from the moment it enters the
>> logic board until the video board (attached to the neck of the CRT).
>> The signal is there (it has different shapes but it is 18KHz). The
>
> No, that is a differe
Hi,
I traced the 18Khz signal all the way from the moment it enters the
logic board until the video board (attached to the neck of the CRT).
The signal is there (it has different shapes but it is 18KHz). The
output of both transistors is 18KHz and so is the output of the
transformer. I traced it a
Hi,
I recently got a very nice HP 9816 with a 9121 drive unit from Earl
Baugh (thanks Earl!). The computer worked fine but the primary drive
of the 9121 refused to read the disk and made a continuous beating
noise. After I cleaned it on the outside I opened it to see what is
wrong with it. And I f
