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@ -13,108 +13,6 @@ The problem is that I/O is pretty difficult. No one with one of these
machines has come forward with the ability to get anything into or out of the
existing serial port.
The goal: get data into and out of the TLC machine. Hard to do without functional I/O.
The goal: get data into and out of the TLC machine. Hard to do without functional I/O. Well, now - we have functional I/O.
### Audio and Joystick to the rescue
One thing the TLC _does_ have is sound. And a headphone jack. So we have... output.
Looming on the horizon is bit-banged serial data via the joystick port. So we have...
input.
#### A long time ago...
In the dark ages, when dinosaurs roamed the Earth, there was cassette tape.
As an analog-digital storage medium. It was slow, crappy, error-prone, and all
that - but it at least worked.
Early Apple II specimens came with this audio interface built-in - the original Apple ][,
all the way through to the last Apple IIe.
But the audio jacks and attendant ROM code was missing from the IIgs, the IIc, and the IIc+.
And the TLC.
#### Steal all teh cassette ROM
Handily enough, the early ROM code is quite tidy and compact; this is before the days of the crazy
gymnastics of the IIe and beyond that moved Heaven and Earth to keep the entry points constant
(because programmers are bad, and used them literally). The angle of attack:
* Copy out just enough Apple II ROM code to do the moral equivalent of the monitor's save memory to tape command (i.e. `*300.400W`)
* Change cassette output (`$C020`) to speaker output (`$C030`)
* Assemble and get a raw hex dump of that code
* Type that code into the TLC's RAM and run it, dumping all non-banked ROM (`$C100-$FFFF`)
* Capture the audio on a modern computer (Windows hint: run `soundrecorder /file path\to\filename.wav` to get a `.wav`, not a `.wma`)
* Run that audio through CiderPress, which knows how to take tape audio and reconstruct data from it
* ???
* Profit
The source code to do these activities is in the `src` directory, and the resulting ROM from the Tiger Learning computer is in the `rom` directory. A few pictures of the machine and its on-screen interface are in `doc/images`.
## ROM contents
Nonbanked ROM dump is available in binary and in monitor ROM disassembly form:
* [`C100-FFFF.bin`](https://github.com/david-schmidt/tlc-apple2/blob/master/rom/C100-FFFF.bin) - Raw binary
* [`C100-FFFF.txt`](https://github.com/david-schmidt/tlc-apple2/blob/master/rom/C100-FFFF.txt) - Monitor disassembly
Banked ROM exists in slots 2 and 3. The contents have been dumped as follows:
Slot 2:
* [`S2-C800-CFFF.bin`](https://github.com/david-schmidt/tlc-apple2/blob/master/rom/S2-C800-CFFF.bin) - Raw binary
* [`S2-C800-CFFF.txt`](https://github.com/david-schmidt/tlc-apple2/blob/master/rom/S2-C800-CFFF.txt) - Monitor disassembly
Slot 3:
* [`S3-C800-CFFF.bin`](https://github.com/david-schmidt/tlc-apple2/blob/master/rom/S3-C800-CFFF.bin) - Raw binary
* [`S3-C800-CFFF.txt`](https://github.com/david-schmidt/tlc-apple2/blob/master/rom/S3-C800-CFFF.txt) - Monitor disassembly
## File contents
The TLC comes with a virtual disk available in slot 6, drive 1 as volume `/LTWIN`. This is the volume that is booted when the machine turns on.
The contents of it are as follows:
```
]catalog
/LTWIN
NAME TYPE BLOCKS MODIFIED CREATED ENDFILE SUBTYPE
BASIC.SYSTEM SYS 21 6-DEC-91 16:48 6-DEC-91 16:48 10240
PRODOS SYS 35 6-MAY-93 17:10 2-NOV-92 21:09 17128
STARTUP BAS 1 <NO DATE> <NO DATE> 176
KERLT101 BIN 50 11-JAN-96 9:18 11-JAN-96 9:18 24764 A=$1400
BLOCKS FREE: 14 BLOCKS USED: 114 TOTAL BLOCKS: 128
```
#### STARTUP
Bootstrapping the TLC follows the normal Apple II boot sequence and loads up `PRODOS` and then runs the `STARTUP` Applesoft program from `/LTWIN`.
`STARTUP` looks like this:
```
]load startup
]list
10 PRINT CHR$ (4);"BLOAD KERLT101"
20 CALL 5120
30 A = PEEK (25)
40 IF A=1THEN GOTO 10
50 HOME
60 VTAB 10: HTAB 10: PRINT "To return to Desktop,"
70 VTAB 11: HTAB 11: PRINT "please type LTWIN"
80 POKE (49304),0
90 POKE (49326),1
100 END
```
The command `LTWIN` is a command that Tiger inserted into the ProDOS external command list (clumsily)
that basically reboots the system so that you end up back at the graphical interface.
#### KERLT101
The contents of `KERLT101` has been dumped and the beginnings of a [6502bench SourceGen](https://github.com/fadden/6502bench/releases) project are here:
* [`KERLT101.bin`](https://github.com/david-schmidt/tlc-apple2/blob/master/file/KERLT101.bin) - Raw binary
* [`KERLT101.bin.dis65`](https://github.com/david-schmidt/tlc-apple2/blob/master/file/KERLT101.bin.dis65) - SourceGen disassembly project
* [`KERLT101.bin_cc65.lst`](https://github.com/david-schmidt/tlc-apple2/blob/master/file/KERLT101.bin_cc65.lst) - ca65 assembly output listing
Entry is at $1400 which immediately jumps over a data area and starts up for real at $171F. There are clearly a lot of softswitches in the $C0xx space
that the TLC is using. Figuring out what they do should be an interesting challenge.
[Continue to TLC Wiki...](../../wiki)