600D Control Register Expander

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Steve Gray
Posts: 321
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
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600D Control Register Expander

Post by Steve Gray »

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
OSI-CRX.jpg (146.55 KiB) Viewed 5789 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.

Steve
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.
waltermixxx
Posts: 129
Joined: Sun Feb 03, 2019 10:31 pm

Re: 600D Control Register Expander

Post by waltermixxx »

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. :)
MK14HAK
Posts: 356
Joined: Wed Mar 16, 2011 1:49 am
Location: New Zealand

Re: 600D Control Register Expander

Post by MK14HAK »

Interested. Could same be done for C4 ?
600RevB:16K,2MHz,64x32,470,CEGMON
SuperKit:502,540B,542B,CEGMON, 8" and 5" FDDs
Cards:PE IO,6522 D-A-D, AY3-8910,ProgramGraphics,Color,UK101
WIP:HexDOS,FDD Emulator
Steve Gray
Posts: 321
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
Contact:

Re: 600D Control Register Expander

Post by Steve Gray »

Sure, it should be possible. I believe you'd just need to feed D4 to D7 into the new latch chip.

Steve
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.
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