I almost surely have schematics and specs for all of this. What should I look for to assist? Or stop by at your convenience. I have reorganized the OSI stuff to make it easier to use and I have been planning to explore the 400 series stuff. Bill On Mon, May 22, 2023, 8:02 PM Alexander Pierson via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:

Bill & Bill, Mr. Degnan, I had seen your 400 board photo on vintagecomputer.net, which I used as a reference during the construction of my replica from glitchworks (which is now running!), but I had not seen the rest of the image set including the 440. That will be helpful as a reference, as I've only found photos of 4 other units out there. Seems yours has the last two RAM sockets populated for color.

The documents for both the 440 and 420c available online from osiweb & Mark's OSI archive are ones provided by Mr. Dromgoole himself, so thank you for having uploaded those -- without them, I'd be up a creek. Also, good to know about Mike's ASCII keyboard adapter.

I've also come across what might be an example of an original Challenger with a 440 and a 420c on DigiBarn's page. They're the cards farthest from the nameplate. https://www.digibarn.com/collections/systems/challenger/page_01.htm

I wish attending a workshop was in the cards for me, but the distance/time tends to clash with my work schedule.

Thank you, -Alexander 'Z' Pierson On Monday, May 22, 2023 at 01:41:05 PM EDT, Bill Degnan via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:

Maybe I will bring my osi 400 stuff to the upcoming vcfed workshop, If I can go and have coverage at the museum then B

On Mon, May 22, 2023, 12:43 PM Bill Dromgoole via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:

...

You just need an ascii keyboard with TTL level outputs for the 440 video board. The input is enabled for one micro second every five milliseconds by the OSI 65V ROM. This means you need a keyboard strobe pulse about 10 milliseconds long for it to work. You can use M. Willigals PC keyboard to apple 1 adapter board for testing purposes if you want. The early version only had a pulse width of 125 microseconds though. I had to use a 74ls123 with a 15K resistor and a 1.1 microfarad capacitor between the adapter and the 440 to get the correct pulse width.

He no longer sells the board but can build your own. http://www.willegal.net/appleii/appleii-kb-int.htm

Bill From: Alexander Pierson via vcf-midatlantic Sent: Monday, May 22, 2023 9:37 AM To: vcf-midatlantic@lists.vcfed.org Cc: Alexander Pierson Subject: [vcf-midatlantic] Ohio Scientific 440 Video Board