Initial commit

.gitignore

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+.project

README.md

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+# tlc-apple2
+Some bits and bobs regarding the Tiger Learning Computer.
+The TLC was a "toy" computer that had an Apple IIe at its core.
+There was a UI that would come up by default that was an early,
+proprietary windowing system that was little more than a program launcher.
+
+The TLC can be booted and you can get into Applesoft BASIC without any problem.
+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 the ROM data of the TLC out of the machine.  Hard to do with funcitonal I/O.
+
+### Audio to the rescue
+
+One thing the TLC _does_ have is sound.  And a headphone jack.  So we have... output.
+
+#### 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
+ * 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.

src/make.bat

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+ca65 tapeout.asm -l tapeout.lst
+ld65 tapeout.o -o tapeout.bin -C tapeout.cfg

src/tapeout.asm

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+; da65 V2.13.9 - (C) Copyright 2000-2009,  Ullrich von Bassewitz
+; Created:    2020-06-04 02:08:05
+
+        .setcpu "6502"
+
+
+.org $0300
+
+        lda     #$00
+        ldy     #$03
+        sta     $3c
+        sty     $3d
+        lda     #$00
+        ldy     #$04
+        sta     $3e
+        sty     $3f
+        jsr     WRITE
+        rts
+
+LFCBA:  lda     $3C
+        cmp     $3E
+        lda     $3D
+        sbc     $3F
+        inc     $3C
+        bne     LFCC8
+        inc     $3D
+LFCC8:  rts
+
+LEADER:
+LFCC9:  ldy     #$4B
+        jsr     LFCDB
+        bne     LFCC9
+        adc     #$FE
+        bcs     LFCC9
+        ldy     #$21
+LFCD6:  jsr     LFCDB
+        iny
+        iny
+LFCDB:  dey
+        bne     LFCDB
+        bcc     LFCE5
+        ldy     #$32
+LFCE2:  dey
+        bne     LFCE2
+LFCE5:  ldy     $C030
+        ldy     #$2C
+        dex
+        rts
+
+WRITE:
+        lda     #$40
+        jsr     LFCC9
+        ldy     #$27
+LFED4:  ldx     #$00
+        eor     ($3C,x)
+        pha
+        lda     ($3C,x)
+        jsr     LFEED
+        jsr     LFCBA
+        ldy     #$1D
+        pla
+        bcc     LFED4
+        ldy     #$22
+        jsr     LFEED
+        beq     LFF3A
+LFEED:  ldx     #$10
+LFEEF:  asl     a
+        jsr     LFCD6
+        bne     LFEEF
+        rts
+
+LFF3A:  lda     #$DA
+        jmp     $FDED

src/tapeout.cfg

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+MEMORY {
+    RAM: start = $0300, size = $6500, define = yes, file = %O;
+}
+
+SEGMENTS {
+    CODE: load = RAM, type = ro;
+    RODATA: load = RAM, type = ro;
+    BSS: load = RAM, type = bss;
+}

src/tapeout.txt

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+This is the part you get to type in by hand if you
+have no other way to communicate to a machine.
+Begin and end addresses are two-byte LSB/MSB pointers
+in $3c/$3d and $3e/$3f; they are loaded for you from 
+$301/$303 and $309/$30b if you just want to call
+the entry point at $300.  Otherwise, fill them in
+directly and call the WRITE entry point at $346.
+
+When the sound output is complete, a "Z" will be 
+printed and you'll be back at the prompt.  (The
+original monitor code would print a Ctrl-G (beep),
+which is not desirable now.)
+
+300:A9 00 A0 03 85 3C 84 3D A9 00 A0 04 85 3E 84 3F 
+310:20 46 03 60 A5 3C C5 3E A5 3D E5 3F E6 3C D0 02 
+320:E6 3D 60 A0 4B 20 35 03 D0 F9 69 FE B0 F5 A0 21 
+330:20 35 03 C8 C8 88 D0 FD 90 05 A0 32 88 D0 FD AC 
+340:30 C0 A0 2C CA 60 A9 40 20 23 03 A0 27 A2 00 41 
+350:3C 48 A1 3C 20 66 03 20 14 03 A0 1D 68 90 EE A0 
+360:22 20 66 03 F0 09 A2 10 0A 20 30 03 D0 FA 60 A9 
+370:DA 4C ED FD