Re: [midatlanticretro] Re: Ferguson BigBoard disk help needed
- On Sat, 25 May 2013, Dave McGuire wrote:
>That would be much appreciated if you maintain motivation.
> On 05/25/2013 12:01 AM, Cory Smelosky wrote:
>>>>> Yes. Closer (but still not "close") inspection suggests that it might be a
>>>>> clock speed mod. Further supporting this guess is that all the Z80-family
>>>>> components on the board are the Z80B variants, 6MHz. That'd be a pretty
>>>>> expensive pointless upgrade for a board clocked at 2.5MHz! I suspect (from
>>>>> the clock crystal still being 20MHz) that it's a 5MHz modification.
>>>> Ahhh. That does seem like a fairly pointless upgrade...
>>>> How much memory?
>>> 64KB, four rows of 4116s. Full-up and pretty swank for a Z80.
>>> I've been drinking a bit, and it's getting a bit late, but I think I'm
>>> going to go fire it up in the lab on a bench supply and see if it generates
>>> some video.
>> Good luck!
> Thanks! If I actually maintain motivation (it's been a long week) and make
> some progress on this tonight, I will report back, maybe with some pictures.
> Dave McGuire, AK4HZ
> New Kensington, PA
> Yahoo! Groups Links
http://gewt.net/ Personal stuff
- On 05/25/2013 01:02 AM, Cory Smelosky wrote:
>>>> I've been drinking a bit, and it's getting a bit late, but I think I'mWell I've made some progress. No pics, because there's nothing much to
>>>> going to go fire it up in the lab on a bench supply and see if it
>>>> some video.
>>> Good luck!
>> Thanks! If I actually maintain motivation (it's been a long week)
>> and make
>> some progress on this tonight, I will report back, maybe with some
> That would be much appreciated if you maintain motivation.
take pictures of, because I can't get very far without a keyboard. The board
comes up and does exactly what it's supposed to do with no keyboard...which
is to generate blank video.
But, no smoke! First, I verified that the CPU is actually executing code
by looking at a few lines on the address and data buses with an oscilloscope,
and they looked good. Then I looked at the composite video output, and that
looked good too.
Perhaps tomorrow I will rig up a parallel keyboard and get to the next
step. You have to press <cr> to tell the ROM-based monitor to come up.
I seem to recall something about the BigBoard being able to be jumpered to
tell it to use one of the serial ports as the console, at least for the
monitor, but I'll have to hit the manual for that. Perhaps tomorrow.
Dave McGuire, AK4HZ
New Kensington, PA
- Ciao Dave,
you're taking the proper way to turn the card. Even with the the clock modification you mentioned it seems that the cleaning of the screen is the correct event. To me it happened that I had to press the CR on the keyboard. If I remember correctly the eighth bit of the keyboard connector must be connected to ground because the system knows forever to use the keyboard parallel. I'm not having keyboards parallel I built a PS2 adapter to parallel for to use any ps2 keyboard. If you are familiar with the RS232 signals with the help of rs232 interface analyzer you can check the correct jumpers to do and connect to the card using sw like teratem via RS232. I have created a special selfbuilt cable to use a 3.5 "drive that I use normally. On Bitsavers you can find magazine Microcornucopia whose good part of the first issues was scanned by me wanting to delve into the context of those old times of the board. At that time an Italian compait first turn on http://www.vintagesbc.it/wp-content/uploads/2011/12/Foto2858.jpg . Here and below , however, you can see other cards that have made further changes as i said http://www.vintagesbc.it/?page_id=305 All pages have a flag in the upper right to get the not perfect, but (right for me ;) ) automatic translation by google service.