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https://github.com/bkw777/requad
A modified respin of Steven Adolph's QUAD memory expansion for the TRS-80 Model 100
https://github.com/bkw777/requad
Last synced: 25 days ago
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A modified respin of Steven Adolph's QUAD memory expansion for the TRS-80 Model 100
- Host: GitHub
- URL: https://github.com/bkw777/requad
- Owner: bkw777
- License: other
- Created: 2022-08-22T06:18:27.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2024-11-21T11:19:23.000Z (about 1 month ago)
- Last Synced: 2024-11-21T12:24:11.344Z (about 1 month ago)
- Language: Assembly
- Size: 47.3 MB
- Stars: 3
- Watchers: 2
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# reQUAD
## About
This is a derivative of [QUAD](http://bitchin100.com/wiki/index.php?title=QUAD) by Steve Adolph.
## Differences from the original
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.
## To Build it
PCB [PCBWAY](https://www.pcbway.com/project/shareproject/reQUAD_RAM_Expansion_for_TRS_80_Model_100_8690cd19.html)
BOM [DigiKey](https://www.digikey.com/short/z47bn0mw)
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.
## To Use it
The device disables and replaces the machine's original internal 32k RAM, so copy any files off of the computer before installing the reQUAD. You won't be able to access the internal ram except by removing the reQUAD.
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 blindly 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.
### Manual Control
To switch banks manually without 0QUAD:
In BASIC, type `OUT 128,n`, where n is the desired bank number from 0 to 3,
then immediately press RESET on the back of the machine.
`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
The currently executing main rom code has no knowledge that it's entire ram universe has been replaced and all it's current pointers and such are invalid, so the main rom must be restarted IMMEDIATELY after the OUT command.
So after the OUT command, ignore the screen no matter what it looks like happened, whether it looks like nothing happened or whether it looks like it crashed in some way, just ignore the screen and just press the RESET button on the back of the machine.
Pressing RESET is only needed when switching manually this way instead of using 0QUAD.
0QUAD restarts the main rom itself gracefully.
### Software Control
Install [0QUAD](APP/)
Refer to the docs for the original [QUAD](http://bitchin100.com/wiki/index.php?title=QUAD)
### Example Installing 0QUAD using dl2 and teeny
(this will wipe all data)
QUAD.BA must be copied as a binary via TPDD, it can't be copied in ascii format using ordinary text transfer with TELCOM.
This example will use dl2 on the pc and install TEENY on the 100 and then use both TEENY and dl2 to copy QUAD.BA to the 100.
You can use any TPDD emulator like LaddieAlpha or a Backpack instead of dl2, and you can use any TPDD client like TS-DOS or DSKMGR instead of TEENY.
On the pc, install [dl2](https://github.com/bkw777/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
Thanks to Steve Adolph for sharing his original design and allowing this derivative.