This is a derivative of QUAD by Steve Adolph.
Removed the resistor-cap power-on-reset circuit and resettable flip-flop for a simple flip-flop.
Added battery and battery-change cap.
Added pulldown on the sram CE2.
Build notes,
The pin 1 mark on DA1, BAV756S, is tiny and faint, but there is one, you just need a lot of magnification and light. The markings look like .A7t and the . is at pin 1. The pinout is not symmetric, and so the part must be installed in the correct orientation.
The first time the device is powered up, it will be in a random bank number.
The first thing you should do after install is explicitly switch to bank 1.
In BASIC type OUT 128,0 [Enter],
then ignore any messages and immediately press RESET.
Only RESET, or CTRL+BREAK+RESET, but NOT power-cycle!
Power-cycle will make the bank number unknown and random again.
And then either install 0QUAD or at least create an empty text file named BANK1 so that you can identify which bank you are in. Then repeat for banks 2, 3, 4.
After that, either 0QUAD or the text file names will let you see which bank you are in at any time, for instance after a power-cycle.
Switch banks by typing OUT 128,n in BASIC, where n is the desired bank number from 0 to 3,
OUT 128,0 switches to bank 1
OUT 128,1 switches to bank 2
OUT 128,2 switches to bank 3
OUT 128,3 switches to bank 4
Then ignore any error messages or any other screen activity,
and immediately press the reset button on the back of the machine.
The OUT command might seem to do nothing, or might generate some error message, or might exit to the main menu, or lock up the machine, or might seem to do almost anything.
Ignore all of that. It doesn't matter what the machine does, just always press the reset button once immediately after the OUT command.
This is only when switching manually this way. 0QUAD performs a managed graceful switch that restarts the main rom itself.
Install 0QUAD
Refer to the docs for the original QUAD
(this will wipe all data)
On the pc, install dl2
On the 100, in BASIC: OUT 128,0
Then do a cold reset: CTRL+BREAK+RESET
On the pc:
$ cd APP
$ dl -v -b TEENY.100 && dl -v -u
On the 100, in BASIC: RUN "COM:98N1ENN"
Press ENTER at the end of the TEENY install to accept the default install location.
CLEAR 0,62213
Press F8 to exit to the main menu and run TEENY.CO
Use TEENY to copy QUAD.BA from the pc
> L QUAD .BA
> Q
On the pc: Ctrl+C to exit dl2
On the 100: Run QUAD.BA
Answer "1" to the "Which bank?" question.
0QUAD is now installed in bank 1, but is invisible.
Type 0QUAD at the main menu (not in BASIC) to run 0QUAD
Now the top-right corner will show "#1" to show that you are currently in bank 1.
Press F1 to pull up the bank-switch menu, then press F2 to switch to bank 2.
You are now in bank 2 which is a new empty bank.
0QUAD is not installed in this bank yet.
Install 0QUAD in bank 2 by repeating everything after the OUT command above, including the cold reset.
Answer "2" at the "Which bank?" question.
Repeat again for banks 3 and 4.
Once 0QUAD is installed in all banks, you can use it to switch from any bank to any other bank, and you don't need to press the reset button after each switch when using 0QUAD to switch.
Thanks to Steve Adolph for sharing his original design and allowing this derivative.