I'm spending the morning reading the MAME Canon Cat "driver" sourcecode to see if I can figure out how to use it. Simply running it, I can't figure out where essential things like the LEAP keys are.
The code is well commented, which is fortunate because my C++ is rusty, and I don't even know how to configure MAME let alone write drivers for it.
As I read through the code I feel like I'm starting to get the hang of how MAME models things, and I'm realizing that learning the fundamentals of that would have made understanding this much easier.
I'm also remembering a book I read about recreating video game hardware using FPGAs and realizing that the approaches outlined in that book might apply well to the task at hand.
There's a lot of `TODO`s in this code, and it's clear that there's a lot of work to be done before I could use it on a regular basis for real work. Maybe I could help cross some of those off the list, but clearly the author has done a lot of homework on this machine and I'm starting to wonder why the last commit is from two years ago...
Honestly this reads a lot how the VHDL code I've read is structured.
There seems to be a fair amount of code compensating for the differences between the behavior of the simulated hardware and the real thing.
AH, here we go, the keyboard map!
```
PORT_START("Y0")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_N) PORT_CHAR('n') PORT_CHAR('N')
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_M) PORT_CHAR('m') PORT_CHAR('M')
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_K) PORT_CHAR('k') PORT_CHAR('K')
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_J) PORT_CHAR('j') PORT_CHAR('J')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_Y) PORT_CHAR('y') PORT_CHAR('Y')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_T) PORT_CHAR('t') PORT_CHAR('T')
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_6) PORT_CHAR('6') PORT_CHAR(0xA2)
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_5) PORT_CHAR('5') PORT_CHAR('%')
PORT_START("Y1")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_B) PORT_CHAR('n') PORT_CHAR('B')
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_COMMA) PORT_CHAR(',') PORT_CHAR('<')
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_L) PORT_CHAR('l') PORT_CHAR('L')
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_H) PORT_CHAR('h') PORT_CHAR('H')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_U) PORT_CHAR('u') PORT_CHAR('U')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_R) PORT_CHAR('r') PORT_CHAR('R')
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_7) PORT_CHAR('7') PORT_CHAR('&')
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_4) PORT_CHAR('4') PORT_CHAR('$')
PORT_START("Y2")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_V) PORT_CHAR('v') PORT_CHAR('V')
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_STOP) PORT_CHAR('.') PORT_CHAR('>')
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_COLON) PORT_CHAR(';') PORT_CHAR(':')
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_G) PORT_CHAR('g') PORT_CHAR('G')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_I) PORT_CHAR('i') PORT_CHAR('I')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_UNUSED) // totally unused
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_8) PORT_CHAR('8') PORT_CHAR('*')
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_3) PORT_CHAR('3') PORT_CHAR('#')
PORT_START("Y3")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_C) PORT_CHAR('c') PORT_CHAR('C')
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Left USE FRONT") PORT_CODE(KEYCODE_LCONTROL)
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_QUOTE) PORT_CHAR('\'') PORT_CHAR('"')
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_F) PORT_CHAR('f') PORT_CHAR('F')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_O) PORT_CHAR('o') PORT_CHAR('O')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_E) PORT_CHAR('e') PORT_CHAR('E')
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_9) PORT_CHAR('9') PORT_CHAR('(')
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_UNUSED) // totally unused
PORT_START("Y4")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_X) PORT_CHAR('x') PORT_CHAR('X')
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Right USE FRONT") PORT_CODE(KEYCODE_RCONTROL)
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Right Shift") PORT_CODE(KEYCODE_F2) // intl only: latin diaresis and latin !; norway, danish and finnish * and '; others
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_D) PORT_CHAR('d') PORT_CHAR('D')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_P) PORT_CHAR('p') PORT_CHAR('P')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_W) PORT_CHAR('w') PORT_CHAR('W')
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_0) PORT_CHAR('0') PORT_CHAR(')')
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_2) PORT_CHAR('2') PORT_CHAR('@')
PORT_START("Y5")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_Z) PORT_CHAR('z') PORT_CHAR('Z')
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_SPACE) PORT_CHAR(' ')
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Return") PORT_CODE(KEYCODE_ENTER) PORT_CHAR(13)
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_S) PORT_CHAR('s') PORT_CHAR('S')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_OPENBRACE) PORT_CHAR(0xBD) PORT_CHAR(0xBC) //PORT_CHAR('}') PORT_CHAR('{')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_Q) PORT_CHAR('q') PORT_CHAR('Q')
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_MINUS) PORT_CHAR('-') PORT_CHAR('_')
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_1) PORT_CHAR('1') PORT_CHAR('!')
PORT_START("Y6")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Left Shift") PORT_CODE(KEYCODE_F1) // intl only: latin inv ? and inv !; norway and danish ! and |; finnish <>; others
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Left LEAP") PORT_CODE(KEYCODE_LALT)
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_SLASH) PORT_CHAR('/') PORT_CHAR('?')
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_A) PORT_CHAR('a') PORT_CHAR('A')
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_CLOSEBRACE) PORT_CHAR(']') PORT_CHAR('[')
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_TAB) PORT_CHAR('\t')
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_EQUALS) PORT_CHAR('=') PORT_CHAR('+')
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_UNUSED) // totally unused
PORT_START("Y7")
PORT_BIT(0x01, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Shift") PORT_CODE(KEYCODE_RSHIFT) PORT_CODE(KEYCODE_LSHIFT) PORT_CHAR(UCHAR_SHIFT_1)
PORT_BIT(0x02, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Right Leap") PORT_CODE(KEYCODE_RALT)
PORT_BIT(0x04, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Page") PORT_CODE(KEYCODE_PGUP) PORT_CODE(KEYCODE_PGDN)
PORT_BIT(0x08, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Shift Lock") PORT_CODE(KEYCODE_CAPSLOCK)
PORT_BIT(0x10, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("Erase") PORT_CODE(KEYCODE_BACKSPACE)
PORT_BIT(0x20, IP_ACTIVE_LOW, IPT_UNUSED) // totally unused
PORT_BIT(0x40, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_NAME("UNDO") PORT_CODE(KEYCODE_BACKSLASH)
PORT_BIT(0x80, IP_ACTIVE_LOW, IPT_KEYBOARD) PORT_CODE(KEYCODE_TILDE) PORT_CHAR(0xB1) PORT_CHAR(0xB0) // PORT_CHAR('\\') PORT_CHAR('~')
```
So it looks like the "alt" keys are supposed to work as the LEAP keys. I tried this while running the emulator in a browser but maybe something "ate" them before they could get to the emulator? I guess the next logical step is to try running MAME properly on my laptop and see if the results are different.
That said, a close reading of this code reveals a lot of serious gaps in the emulation, essential things like disk I/O that will prevent me from using it until they are sorted. I'm tempted to try and fix/implement these things myself, but given the original authors familiarity with the subject I'm going to guess that adding any of the missing parts isn't going to be easy, and I need to consider the trade-offs of pursuing that path vs. alternatives. Remember, my original motivation for taking the emulation path was to save time.
The other thing that comes to mind as I read this code is that it might be easier (for me at least) to recreate the experience of these machines than it will be to learn enough about their internals and the internals of the emulators to piece-together a complete emulation. Since my objective isn't to create a "screen-accurate" replica, recreation is fine if not ideal for my purposes, but it raises a serious question: is it legal?
Building The Kitten around an emulation of The Cat is pretty straightforward from a legal perspective in that it's no more or less legal than the existing emulation. In most cases this is legal so long as the code (typically ROMs) are sourced legally. I don't know the legal status of the Cat's code, but if I built The Kitten out of readily-available emulation parts I'd at least know I'm not doing anything more illegal than what others have already done.
However, if I recreate it by writing my own version that legal status is less clear. IANAL but using things that are explicitly called-out as copyright, trademark, etc. in the manual like the term "LEAP" definitely raises some flags. I could be cute or clever and try to side-step this by renaming things, but I doubt that's a completely defensible thing legally and it would be doubly sad to resort to such chicanery and still get sued.
The ideal solution would be to figure out who, if anyone still holds these rights and get proper permission.
Of course all of this is predicated on me actually creating any of these things, so perhaps the best approach is to cross the legal bridge when I come to it. If I recreate the Swyft environment "from scratch" for my own personal use there's little chance of inviting litigation, and if by some chance it does, then at least I'll know who to talk to about getting permission to take it any further.
Jason J. Gullickson, 2026