600D Control Register Expander

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Steve Gray
Posts: 281
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada

600D Control Register Expander

Post by Steve Gray » Wed Jun 19, 2019 2:50 pm

Hi, while working on my Monitor ROM Menu code I had the idea that a couple extra control lines might be handy, so I whipped up a little adapter board. This board plugs into U72 and replaces the 74LS174 HEX flip-flop chip with a 74LS273 OCTAL chip, thereby giving two additional controllable lines.
These lines could be used as upper address line (like BK0 and BK1 are used for BASIC ROMS) for roms like the Monitor ROM, or character generator rom, allowing these to be under software control. All lines are brought out to a header, so you can also use it to tap into the existing control lines.

With this the 600D control lines would be:

0- 32/64 column mode
1- Color Enable
2- BK0
3- BK1
4- DAC Disable
5- User Defined (existing)
6- User Defined (expanded)
7- User Defined (expanded)

Here is the board:
OSI-CRX.jpg (146.55 KiB) Viewed 550 times
Please excuse the render. The socket would be a header on the other side of the board....

Let me know if you're interested in something like this.

C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

Posts: 118
Joined: Sun Feb 03, 2019 10:31 pm

Re: 600D Control Register Expander

Post by waltermixxx » Fri Jun 28, 2019 5:25 pm

If you make it, they will come! And yes,
I would like one for sure.

Very clever.
Turning into quite an OSI Junkie (HTFDTH?) Superboard II REV B-40K, 9600b, HC-05 Bluetooth, Superboard II Rev D, C4P rebuild- 502, 542c, 540B. :)

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