2 Copyright 2019,2020 Jun Wako <wakojun@gmail.com>
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>.
29 #include "ibmpc_usb.h"
33 static void matrix_make(uint8_t code);
34 static void matrix_break(uint8_t code);
36 static int8_t process_cs1(uint8_t code);
37 static int8_t process_cs2(uint8_t code);
38 static int8_t process_cs3(uint8_t code);
41 static uint8_t matrix[MATRIX_ROWS];
42 #define ROW(code) ((code>>3)&0x0F)
43 #define COL(code) (code&0x07)
45 static int16_t read_wait(uint16_t wait_ms)
47 uint16_t start = timer_read();
49 while ((code = ibmpc_host_recv()) == -1 && timer_elapsed(start) < wait_ms);
53 static uint16_t read_keyboard_id(void)
59 //code = ibmpc_host_send(0xF5);
62 code = ibmpc_host_send(0xF2);
63 if (code == -1) { id = 0xFFFF; goto DONE; } // XT or No keyboard
64 if (code != 0xFA) { id = 0xFFFE; goto DONE; } // Broken PS/2?
66 // ID takes 500ms max TechRef [8] 4-41
67 code = read_wait(500);
68 if (code == -1) { id = 0x0000; goto DONE; } // AT
69 id = (code & 0xFF)<<8;
71 // Mouse responds with one-byte 00, this returns 00FF [y] p.14
72 code = read_wait(500);
77 //code = ibmpc_host_send(0xF4);
82 void hook_early_init(void)
88 void matrix_init(void)
92 // initialize matrix state: all keys off
93 for (uint8_t i=0; i < MATRIX_ROWS; i++) matrix[i] = 0x00;
99 * keyboard recognition
101 * 1. Send F2 to get keyboard ID
102 * a. no ACK(FA): XT keyobard
103 * b. ACK but no ID: 84-key AT keyboard CodeSet2
104 * c. ID is AB 83: PS/2 keyboard CodeSet2
105 * d. ID is BF BF: Terminal keyboard CodeSet3
106 * e. error on recv: maybe broken PS/2
108 uint8_t current_protocol = 0;
109 uint16_t keyboard_id = 0x0000;
110 keyboard_kind_t keyboard_kind = NONE;
111 uint8_t matrix_scan(void)
113 // scan code reading states
128 static uint16_t init_time;
132 xprintf("\nERR:%02X ISR:%04X ", ibmpc_error, ibmpc_isr_debug);
134 // when recv error, neither send error nor buffer full
135 if (!(ibmpc_error & (IBMPC_ERR_SEND | IBMPC_ERR_FULL))) {
136 // keyboard init again
142 // clear or process error
143 ibmpc_error = IBMPC_ERR_NONE;
147 // check protocol AT/XT
148 if (ibmpc_protocol && ibmpc_protocol != current_protocol) {
149 xprintf("\nPROTO:%02X ISR:%04X ", ibmpc_protocol, ibmpc_isr_debug);
150 current_protocol = ibmpc_protocol;
156 ibmpc_host_disable();
158 xprintf("I%u ", timer_read());
159 keyboard_kind = NONE;
160 keyboard_id = 0x0000;
165 init_time = timer_read();
169 // wait for keyboard to settle after plugin
170 if (timer_elapsed(init_time) > 1000) {
175 ibmpc_host_isr_clear();
177 wait_ms(1); // keyboard can't respond to command without this
179 // SKIDATA-2-DE(and some other keyboards?) stores 'Code Set' setting in nonvlatile memory
180 // and keeps it until receiving reset. Sending reset here may be useful to clear it, perhaps.
181 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#select-alternate-scan-codesf0
184 if (0xFA == ibmpc_host_send(0xFF)) {
189 xprintf("A%u ", timer_read());
192 // Reset XT-initialize keyboard
193 // XT: hard reset 500ms for IBM XT Type-1 keyboard and clones
194 // XT: soft reset 20ms min(clock Lo)
195 ibmpc_host_disable(); // soft reset: inihibit(clock Lo/Data Hi)
196 IBMPC_RST_LO(); // hard reset: reset pin Lo
198 init_time = timer_read();
199 state = XT_RESET_WAIT;
202 if (timer_elapsed(init_time) > 500) {
203 state = XT_RESET_DONE;
207 IBMPC_RST_HIZ(); // hard reset: reset pin HiZ
208 ibmpc_host_isr_clear();
209 ibmpc_host_enable(); // soft reset: idle(clock Hi/Data Hi)
211 xprintf("X%u ", timer_read());
212 init_time = timer_read();
216 // 1) Read BAT code and ID on keybaord power-up
217 // For example, XT/AT sends 'AA' and Terminal sends 'AA BF BF' after BAT
218 // AT 84-key: POR and BAT can take 900-9900ms according to AT TechRef [8] 4-7
219 // AT 101/102-key: POR and BAT can take 450-2500ms according to AT TechRef [8] 4-39
220 // 2) Read key typed by user or anything after error on protocol or scan code
221 // This can happen in case of keyboard hotswap, unstable hardware, signal integrity problem or bug
223 /* wait until keyboard sends any code without 10000ms timeout
224 if (timer_elapsed(init_time) > 10000) {
228 if (ibmpc_host_recv() != -1) { // wait for AA
229 xprintf("W%u ", timer_read());
230 init_time = timer_read();
235 // NOTE: we can omit to wait BF BF
236 // ID takes 500ms max? TechRef [8] 4-41, though 1ms is enough for 122-key Terminal 6110345
237 if (timer_elapsed(init_time) > 500) {
240 if (ibmpc_host_recv() != -1) { // wait for BF
241 xprintf("W%u ", timer_read());
242 init_time = timer_read();
247 if (timer_elapsed(init_time) > 500) {
250 if (ibmpc_host_recv() != -1) { // wait for BF
251 xprintf("W%u ", timer_read());
256 keyboard_id = read_keyboard_id();
257 xprintf("R%u ", timer_read());
259 if (0x0000 == keyboard_id) { // CodeSet2 AT(IBM PC AT 84-key)
260 keyboard_kind = PC_AT;
261 } else if (0xFFFF == keyboard_id) { // CodeSet1 XT
262 keyboard_kind = PC_XT;
263 } else if (0xFFFE == keyboard_id) { // CodeSet2 PS/2 fails to response?
264 keyboard_kind = PC_AT;
265 } else if (0x00FF == keyboard_id) { // Mouse is not supported
266 xprintf("Mouse: not supported\n");
267 keyboard_kind = NONE;
268 #ifdef G80_2551_SUPPORT
269 } else if (0xAB86 == keyboard_id ||
270 0xAB85 == keyboard_id) { // For G80-2551 and other 122-key terminal
271 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#ab86
272 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#ab85
274 if ((0xFA == ibmpc_host_send(0xF0)) &&
275 (0xFA == ibmpc_host_send(0x03))) {
276 // switch to code set 3
277 keyboard_kind = PC_TERMINAL;
279 keyboard_kind = PC_AT;
282 } else if (0xBFB0 == keyboard_id) { // IBM RT Keyboard
283 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#bfb0
284 // TODO: LED indicator fix
285 //keyboard_kind = PC_TERMINAL_IBM_RT;
286 keyboard_kind = PC_TERMINAL;
287 } else if (0xAB00 == (keyboard_id & 0xFF00)) { // CodeSet2 PS/2
288 keyboard_kind = PC_AT;
289 } else if (0xBF00 == (keyboard_id & 0xFF00)) { // CodeSet3 Terminal
290 keyboard_kind = PC_TERMINAL;
292 keyboard_kind = PC_AT;
295 xprintf("\nID:%04X(%d) ", keyboard_id, keyboard_kind);
300 xprintf("S%u ", timer_read());
301 switch (keyboard_kind) {
305 led_set(host_keyboard_leds());
308 // Set all keys to make/break type
309 ibmpc_host_send(0xF8);
310 // This should not be harmful
311 led_set(host_keyboard_leds());
317 xprintf("L%u ", timer_read());
320 uint16_t code = ibmpc_host_recv();
326 // Keyboard Error/Overrun([3]p.26) or Buffer full
327 // Scan Code Set 1: 0xFF
328 // Scan Code Set 2 and 3: 0x00
329 // Buffer full(IBMPC_ERR_FULL): 0xFF
330 if (code == 0x00 || code == 0xFF) {
331 xprintf("\n!OVERRUN![");
333 // read and ignore data
336 } while ((code = ibmpc_host_recv()) != -1);
345 switch (keyboard_kind) {
347 if (process_cs1(code) == -1) state = INIT;
350 if (process_cs2(code) == -1) state = INIT;
353 if (process_cs3(code) == -1) state = INIT;
367 bool matrix_is_on(uint8_t row, uint8_t col)
369 return (matrix[row] & (1<<col));
373 uint8_t matrix_get_row(uint8_t row)
378 uint8_t matrix_key_count(void)
381 for (uint8_t i = 0; i < MATRIX_ROWS; i++) {
382 count += bitpop(matrix[i]);
389 static void matrix_make(uint8_t code)
391 if (!matrix_is_on(ROW(code), COL(code))) {
392 matrix[ROW(code)] |= 1<<COL(code);
397 static void matrix_break(uint8_t code)
399 if (matrix_is_on(ROW(code), COL(code))) {
400 matrix[ROW(code)] &= ~(1<<COL(code));
404 void matrix_clear(void)
406 for (uint8_t i=0; i < MATRIX_ROWS; i++) matrix[i] = 0x00;
409 void led_set(uint8_t usb_led)
411 // Sending before keyboard recognition may be harmful for XT keyboard
412 if (keyboard_kind == NONE) return;
414 // XT keyobard doesn't support any command and it is harmful perhaps
415 // https://github.com/tmk/tmk_keyboard/issues/635#issuecomment-626993437
416 if (keyboard_kind == PC_XT) return;
418 // It should be safe to send the command to keyboards with AT protocol
419 // - IBM Terminal doesn't support the command and response with 0xFE but it is not harmful.
420 // - Some other Terminals like G80-2551 supports the command.
421 // https://geekhack.org/index.php?topic=103648.msg2894921#msg2894921
423 // TODO: PC_TERMINAL_IBM_RT support
424 uint8_t ibmpc_led = 0;
425 if (usb_led & (1<<USB_LED_SCROLL_LOCK))
426 ibmpc_led |= (1<<IBMPC_LED_SCROLL_LOCK);
427 if (usb_led & (1<<USB_LED_NUM_LOCK))
428 ibmpc_led |= (1<<IBMPC_LED_NUM_LOCK);
429 if (usb_led & (1<<USB_LED_CAPS_LOCK))
430 ibmpc_led |= (1<<IBMPC_LED_CAPS_LOCK);
431 ibmpc_host_set_led(ibmpc_led);
435 /*******************************************************************************
436 * XT: Scan Code Set 1
440 * E0-escaped scan codes are translated into unused range of the matrix.(54-7F)
442 * 01-53: Normal codes used in original XT keyboard
443 * 54-7F: Not used in original XT keyboard
445 * 0 1 2 3 4 5 6 7 8 9 A B C D E F
446 * 50 - - - - * * x x x x * * * * * *
447 * 60 * * * * x x x x x x x x x x x *
448 * 70 x * * x * * x * * x * x * x x *
450 * -: codes existed in original XT keyboard
451 * *: E0-escaped codes translated
452 * x: Non-espcaped codes(Some are not used in real keyboards probably)
454 * Codes assigned in range 54-7F:
456 * 50 - 60 Up* 70 KANAx
457 * 51 - 61 Left* 71 Insert*
458 * 52 - 62 Down* 72 Delete*
459 * 53 - 63 Right* 73 ROx
460 * 54 PrintScr* 64 F13x 74 Home*
461 * 55 Pause* 65 F14x 75 End*
462 * 56 Euro2x 66 F15x 76 F24x
463 * 57 F11x 67 F16x 77 PageUp*
464 * 58 F12x 68 F17x 78 PageDown*
465 * 59 Keypad=x 69 F18x 79 HENKANx
466 * 5A LGUI* 6A F19x 7A RCTL*
467 * 5B RGUI* 6B F20x 7B MUHENKANx
468 * 5C APP* 6C F21x 7C RALT*
469 * 5D Mute* 6D F22x 7D JPYx
470 * 5E Volume Down* 6E F23x 7E Keypad,x
471 * 5F Volume Up* 6F Keypad Enter* 7F Keypad/ *
473 static uint8_t cs1_e0code(uint8_t code) {
475 // Original IBM XT keyboard doesn't use E0-codes probably
476 // Some XT compatilble keyobards need these keys?
477 case 0x37: return 0x54; // Print Screen
478 case 0x46: return 0x55; // Ctrl + Pause
479 case 0x5B: return 0x5A; // Left GUI
480 case 0x5C: return 0x5B; // Right GUI
481 case 0x5D: return 0x5C; // Application
482 case 0x20: return 0x5D; // Mute
483 case 0x2E: return 0x5E; // Volume Down
484 case 0x30: return 0x5F; // Volume Up
485 case 0x48: return 0x60; // Up
486 case 0x4B: return 0x61; // Left
487 case 0x50: return 0x62; // Down
488 case 0x4D: return 0x63; // Right
489 case 0x1C: return 0x6F; // Keypad Enter
490 case 0x52: return 0x71; // Insert
491 case 0x53: return 0x72; // Delete
492 case 0x47: return 0x74; // Home
493 case 0x4F: return 0x75; // End
494 case 0x49: return 0x77; // Page Up
495 case 0x51: return 0x78; // Page Down
496 case 0x1D: return 0x7A; // Right Ctrl
497 case 0x38: return 0x7C; // Right Alt
498 case 0x35: return 0x7F; // Keypad /
500 // Shared matrix cell with other keys
501 case 0x5E: return 0x70; // Power (KANA)
502 case 0x5F: return 0x79; // Sleep (HENKAN)
503 case 0x63: return 0x7B; // Wake (MUHENKAN)
506 xprintf("!CS1_E0_%02X!\n", code);
512 static int8_t process_cs1(uint8_t code)
517 // Pause: E1 1D 45, E1 9D C5 [a] (TODO: test)
536 matrix_break(code & 0x7F);
551 matrix_make(cs1_e0code(code));
553 matrix_break(cs1_e0code(code & 0x7F));
598 /*******************************************************************************
599 * AT, PS/2: Scan Code Set 2
601 * Exceptional Handling
602 * --------------------
603 * Some keys should be handled exceptionally. See [b].
605 * Scan codes are varied or prefix/postfix'd depending on modifier key state.
607 * 1) Insert, Delete, Home, End, PageUp, PageDown, Up, Down, Right, Left
608 * a) when Num Lock is off
609 * modifiers | make | break
610 * ----------+---------------------------+----------------------
611 * Ohter | <make> | <break>
612 * LShift | E0 F0 12 <make> | <break> E0 12
613 * RShift | E0 F0 59 <make> | <break> E0 59
614 * L+RShift | E0 F0 12 E0 F0 59 <make> | <break> E0 59 E0 12
616 * b) when Num Lock is on
617 * modifiers | make | break
618 * ----------+---------------------------+----------------------
619 * Other | E0 12 <make> | <break> E0 F0 12
620 * Shift'd | <make> | <break>
622 * Handling: These prefix/postfix codes are ignored.
626 * modifiers | make | break
627 * ----------+---------------------------+----------------------
628 * Ohter | <make> | <break>
629 * LShift | E0 F0 12 <make> | <break> E0 12
630 * RShift | E0 F0 59 <make> | <break> E0 59
631 * L+RShift | E0 F0 12 E0 F0 59 <make> | <break> E0 59 E0 12
633 * Handling: These prefix/postfix codes are ignored.
637 * modifiers | make | break
638 * ----------+--------------+-----------------------------------
639 * Other | E0 12 E0 7C | E0 F0 7C E0 F0 12
640 * Shift'd | E0 7C | E0 F0 7C
641 * Control'd | E0 7C | E0 F0 7C
644 * Handling: These prefix/postfix codes are ignored, and both scan codes
645 * 'E0 7C' and 84 are seen as PrintScreen.
648 * modifiers | make(no break code)
649 * ----------+--------------------------------------------------
650 * Other | E1 14 77 E1 F0 14 F0 77
651 * Control'd | E0 7E E0 F0 7E
653 * Handling: Both code sequences are treated as a whole.
654 * And we need a ad hoc 'pseudo break code' hack to get the key off
655 * because it has no break code.
658 * 'Hanguel/English'(F1) and 'Hanja'(F2) have no break code. See [a].
659 * These two Korean keys need exceptional handling and are not supported for now.
662 static uint8_t cs2_e0code(uint8_t code) {
664 // E0 prefixed codes translation See [a].
665 case 0x11: return 0x0F; // right alt
666 case 0x14: return 0x17; // right control
667 case 0x1F: return 0x19; // left GUI
668 case 0x27: return 0x1F; // right GUI
669 case 0x2F: return 0x5C; // apps
670 case 0x4A: return 0x60; // keypad /
671 case 0x5A: return 0x62; // keypad enter
672 case 0x69: return 0x27; // end
673 case 0x6B: return 0x53; // cursor left
674 case 0x6C: return 0x2F; // home
675 case 0x70: return 0x39; // insert
676 case 0x71: return 0x37; // delete
677 case 0x72: return 0x3F; // cursor down
678 case 0x74: return 0x47; // cursor right
679 case 0x75: return 0x4F; // cursor up
680 case 0x7A: return 0x56; // page down
681 case 0x7D: return 0x5E; // page up
682 case 0x7C: return 0x7F; // Print Screen
683 case 0x7E: return 0x00; // Control'd Pause
685 case 0x21: return 0x65; // volume down
686 case 0x32: return 0x6E; // volume up
687 case 0x23: return 0x6F; // mute
688 case 0x10: return 0x08; // (WWW search) -> F13
689 case 0x18: return 0x10; // (WWW favourites) -> F14
690 case 0x20: return 0x18; // (WWW refresh) -> F15
691 case 0x28: return 0x20; // (WWW stop) -> F16
692 case 0x30: return 0x28; // (WWW forward) -> F17
693 case 0x38: return 0x30; // (WWW back) -> F18
694 case 0x3A: return 0x38; // (WWW home) -> F19
695 case 0x40: return 0x40; // (my computer) -> F20
696 case 0x48: return 0x48; // (email) -> F21
697 case 0x2B: return 0x50; // (calculator) -> F22
698 case 0x34: return 0x08; // (play/pause) -> F13
699 case 0x3B: return 0x10; // (stop) -> F14
700 case 0x15: return 0x18; // (previous track) -> F15
701 case 0x4D: return 0x20; // (next track) -> F16
702 case 0x50: return 0x28; // (media select) -> F17
703 case 0x5E: return 0x50; // (ACPI wake) -> F22
704 case 0x3F: return 0x57; // (ACPI sleep) -> F23
705 case 0x37: return 0x5F; // (ACPI power) -> F24
707 // https://github.com/tmk/tmk_keyboard/pull/636
708 case 0x03: return 0x18; // Help DEC LK411 -> F15
709 case 0x04: return 0x08; // F13 DEC LK411
710 case 0x0B: return 0x20; // Do DEC LK411 -> F16
711 case 0x0C: return 0x10; // F14 DEC LK411
712 case 0x0D: return 0x19; // LCompose DEC LK411 -> LGUI
713 case 0x79: return 0x6D; // KP- DEC LK411 -> PCMM
714 case 0x83: return 0x28; // F17 DEC LK411
715 default: return (code & 0x7F);
719 static int8_t process_cs2(uint8_t code)
721 // scan code reading states
751 case 0x84: // Alt'd PrintScreen
755 case 0xAA: // Self-test passed
756 case 0xFC: // Self-test failed
757 // replug or unstable connection probably
758 default: // normal key make
764 xprintf("!CS2_INIT!\n");
769 case E0: // E0-Prefixed
771 case 0x12: // to be ignored
772 case 0x59: // to be ignored
781 matrix_make(cs2_e0code(code));
784 xprintf("!CS2_E0!\n");
789 case F0: // Break code
795 case 0x84: // Alt'd PrintScreen
805 xprintf("!CS2_F0!\n");
810 case E0_F0: // Break code of E0-prefixed
812 case 0x12: // to be ignored
813 case 0x59: // to be ignored
819 matrix_break(cs2_e0code(code));
822 xprintf("!CS2_E0_F0!\n");
827 // Pause make: E1 14 77
850 // Pause break: E1 F0 14 F0 77
886 * Terminal: Scan Code Set 3
889 * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#scan-code-set-3
891 static int8_t process_cs3(uint8_t code)
896 #ifdef G80_2551_SUPPORT
897 // G80-2551 four extra keys around cursor keys
909 case 0x83: // PrintScreen
912 case 0x84: // Keypad *
915 case 0x85: // Muhenkan
921 case 0x87: // Hiragana
924 case 0x8B: // Left GUI
927 case 0x8C: // Right GUI
930 case 0x8D: // Application
933 #ifdef G80_2551_SUPPORT
934 case 0x80: // G80-2551 four extra keys around cursor keys
938 default: // normal key make
942 xprintf("!CS3_READY!\n");
947 case F0: // Break code
949 case 0x83: // PrintScreen
953 case 0x84: // Keypad *
957 case 0x85: // Muhenkan
965 case 0x87: // Hiragana
969 case 0x8B: // Left GUI
973 case 0x8C: // Right GUI
977 case 0x8D: // Application
986 xprintf("!CS3_F0!\n");
991 #ifdef G80_2551_SUPPORT
993 * G80-2551 terminal keyboard support
994 * https://deskthority.net/wiki/Cherry_G80-2551
995 * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#g80-2551-in-code-set-3
997 case G80: // G80-2551 four extra keys around cursor keys
999 case (0x26): // TD= -> JYEN
1002 case (0x25): // page with edge -> NUHS
1005 case (0x16): // two pages -> RO
1008 case (0x1E): // calc -> KANA
1023 case (0x26): // TD= -> JYEN
1026 case (0x25): // page with edge -> NUHS
1029 case (0x16): // two pages -> RO
1032 case (0x1E): // calc -> KANA
1048 * IBM PC Keyboard Protocol Resources:
1050 * [a] Microsoft USB HID to PS/2 Translation Table - Scan Code Set 1 and 2
1051 * http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/translate.pdf
1053 * [b] Microsoft Keyboard Scan Code Specification - Special rules of Scan Code Set 1 and 2
1054 * http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/scancode.doc
1056 * [1] PS/2 Reference Manuals - Collection of IBM Personal System/2 documents.
1057 * http://www.mcamafia.de/pdf/pdfref.htm
1059 * [2] Keyboard and Auxiliary Device Controller - Signal Timing and Format
1060 * http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
1062 * [3] Keyboards(101- and 102-key) - Keyboard Layout, Scan Code Set, POR, and Commands.
1063 * http://www.mcamafia.de/pdf/ibm_hitrc11.pdf
1065 * [4] IBM PC XT Keyboard Protocol
1066 * https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
1068 * [5] IBM Keyboard Scan Code by John Elliott - 83-key, 84-key, 102-key and 122-key
1069 * https://www.seasip.info/VintagePC/index.html
1071 * [6] IBM 1391406 Keyboard - Scan Code Set 2 of 102-key PS/2 keyboard
1072 * https://www.seasip.info/VintagePC/ibm_1391406.html
1074 * [7] The IBM 6110344 Keyboard - Scan Code Set 3 of 122-key terminal keyboard
1075 * https://www.seasip.info/VintagePC/ibm_6110344.html
1077 * [8] IBM PC AT Technical Reference 1986
1078 * http://bitsavers.org/pdf/ibm/pc/at/6183355_PC_AT_Technical_Reference_Mar86.pdf
1080 * [y] TrackPoint Engineering Specifications for version 3E
1081 * https://web.archive.org/web/20100526161812/http://wwwcssrv.almaden.ibm.com/trackpoint/download.html
1083 * [z] [Soarer's XT/AT/PS2/Terminal to USB converter]
1084 * https://geekhack.org/index.php?topic=17458.0