Amiga 500 Keyboard Schematic Mitsumi

[nocash]

I couldn't find a schematic for the A500 keyboard, so I've drawn one myself...

                 Amiga 500 Keyboard Schematic (nocash, 04 Mar 2016)
  .-------------.
  |      RAM_VCC|1 --VCC     .--R9--VCC          /X7  /X6  /X5  /X4  /X3  /X2
  |     /Y15 PD7|2 -->----.--'- - - - - - - /Y15 N/A  N/A  N/A  N/A  N/A  N/A
  |     /Y14 PD6|3 -->----|---------------- /Y14 NUM* EUL  CAPS TAB  `~   ESC
  |     /Y13 PD5|4 -->----|---------------- /Y13 NUM+ Z    A    Q    1!   NUM(
  |     /Y12 PD4|5 -->----|---------------- /Y12 NUM9 X    S    W    2@   F1
  |     /Y11 PD3|6 -->----|---------------- /Y11 NUM6 C    D    E    3#   F2
  |     /Y10 PD2|7 -->----|---------------- /Y10 NUM3 V    F    R    4$   F3
  |      /Y9 PD1|8 -->----|---------------- /Y9  NUM. B    G    T    5%   F4
  |      /Y8 PD0|9 -->----|---------------- /Y8  NUM8 N    H    Y    6^   F5
  | MOS     XTLI|10-------|----.--C12--GND       |    |    |    |    |    |
  | 6570    XTLO|11-------|--. Y1                |    |    |    |    |    |
  | -036     GND|12--GND  |  '-'--C13--GND       |    |    |    |    |    |
  |      /Y7 PC7|13-->----|---------------- /Y7  NUM5 M    J    U    7&   NUM)
  | 6502 /Y6 PC6|14-->----|---------------- /Y6  NUM2 ,<   K    I    8*   F6
  |      /Y5 PC5|15-->----|---------------- /Y5  ENTR .>   L    O    9(   NUM/
  |      /Y4 PC4|16-->----|---------------- /Y4  NUM7 /?   ;:   P    0)   F7
  |      /Y3 PC3|17-->----|---------------- /Y3  NUM4 N/A  '"   [{   -_   F8
  |      /Y2 PC2|18-->----|---------------- /Y2  NUM1 SPC  EUR  ]}   =+   F9
  |      /Y1 PC1|19-->----|---------------- /Y1  NUM0 BS   DEL  RET  \|   F10
  |      /Y0 PC0|20-->----|---------------- /Y0  NUM- DOWN RGHT LEFT UP   HELP
  |         CNTR|21--GND  |                      |    |    |    |    |    |
  | CAPS_LED PB7|22-->----|-.                    |    |    |    |    |    |
  |    /LAMI PB6|23<------|-|-- key              |    |    |    |    |    |
  |    /LALT PB5|24<------|-|-- key              |    |    |    |    |    |
  |    /LSHT PB4|25<------|-|-- key              |    |    |    |    |    |
  |    /CTRL PB3|26<------|-|-- key              |    |    |    |    |    |
  |    /RAMI PB2|27<------|-|-- key  .--C3--GND  |    |    |    |    |    |
  |    /RALT PB1|28<------|-|-- key  +--C4--GND  |    |    |    |    |    |
  |    /RSHT PB0|29<------|-|-- key  +--C14-GND  |    |    |    |    |    |
  |     MAIN_VCC|30-------|-|--------'----VCC    |    |    |    |    |    |
  |      /X7 PA7|31<------|-|--------------------'    |    |    |    |    |
  |      /X6 PA6|32<------|-|-------------------------'    |    |    |    |
  |      /X5 PA5|33<------|-|------------------------------'    |    |    |
  |      /X4 PA4|34<------|-|-----------------------------------'    |    |
  |      /X3 PA3|35<------|-|----------------------------------------'    |
  |      /X2 PA2|36<------|-|---------------------------------------------'
  |   SIOCLK PA1|37-->----|-|----------------------------------------------.
  |   SIODAT PA0|38<->----|-|---------------------------------------------.|
  |  /RESET /RES|39<------|-|-------------------------------------------. ||
  |         /NMI|40--VCC  | |                     ______                | ||
  '-------------'         | '-------------R10---E|Q2 NPN\               | ||
     .--------------------'                      |BC458C |B--R4--/CAPS  | ||
     |     .------------.  VCC--R7--.      GND--C|______/         LED   | ||
     '--> 1|/TR  74   RC|15---------+                                   | ||
    VCC-- 2|TR   LS    C|14---C10+--'    .------------.  VCC--R8--.     | ||
    VCC-- 3|/RST 123   Q|13------------>9|/TR  74   RC|7 ---------+     | ||
    VCC--16|VCC       /Q|4 --     VCC--10|TR   LS    C|6 ---C11---'     | ||
           '------------'         VCC--11|/RST 123   Q|5 ------.        | ||
                                  GND-.-8|GND       /Q|12--    |        | ||
   /Y15 pulsed alive        VCC--C7---'  '------------'        |        | ||
  .------------------------------------------------------------'        | ||
  |                _____                                                | ||
  |      /LAMI-- 3| NOR \    VCC--R1--.    ______                       | ||
  |      /CTRL-- 4|74LS27|6-----------'--E|Q1 NPN\     .--R3--VCC       | ||
  |      /RAMI-- 5|_____/                 |BC458C |B---+                | ||
  |                                 GND--C|______/     +--C9--GND       | ||
  |  .-------------------------------------------------'                | ||
  |  |     .-----C6-------.                 .---------------------------' ||
  |  |     |  .--------.  |                 |                 .--C2--GND  ||
  |  | GND-'-1|GND  VCC|8-'-VCC             |           .-----'-----------'|
  |  '-------2|TRIG Dis|7---.---+---R2--VCC |           |  .--.------------'
  |  .-------3|OUT  Thr|6---'   '--+C5--GND |           |  |  '--C1--GND
  |  | VCC---4|/RES  CV|5---C8----------GND |           |  |
  |  |        | HA17555|                    |           |  |           .----.
  |  |        '--------'                    |           |  '----[FB1]-1|KCLK|
  |  |        _____                         |           '-------[FB2]-2|KDAT|
  |  +----- 9| NOR \    /RESET to amiga     |           .-------[FB4]-3|/RES|
  |  +-----10|74LS27|8----------------------------------'  VCC--[FB3]-4|+5V |
  |  +-----11|_____/                        |                       --5|NC  |
  |  |        _____                         |         RED LEDS   GND--6|GND |
  |  +----- 1| NOR \    /RESET to 6502      |    GND--|<|--|<|--R6----7|PWR |
  |  '----- 2|74LS27|12---------------------'    GND--|<|--|<|--R5----8|DRV |
  '--------13|_____/                                 GREEN LEDS        '----'
                                                                        amiga
    1   3   5   7   9   11  13  15  17  19  21  23  25  27  29  31      cable
  .----------------------------------------------------------------.
  |X4  X6  X3  X2  VCC  CTL LAL Y14 Y12 Y10 Y8  Y6  Y4  Y2  Y0  LED| membrane
  |  X5  X7  RSH  RAL RAM LSH LAM Y13 Y11 Y9  Y7  Y5  Y3  Y1  GND  | connector
  '----------------------------------------------------------------'
      2   4   6   8   10  12  14  16  18  20  22  24  26  28  30

GIF Version Attachment 47797
TXT Version Attachment 47798

Plus, Component list...

Amiga 500 Keyboard Component List
  PCB "MITSUMI, MTM-4V-0, PCB A-500, 56 A620A"
  IC  40pin  MOS 6570-036 (keyboard controller, 6500/1 one-chip microcomputer)
  IC  16pin  74LS123   (dual retriggerable monostable multivibrators)
  IC  14pin  74LS27    (triple 3-input NOR gates)
  IC   8pin  HA17555   (precision timer, compatible with NE555)
  Y1   2pin  3.000MHz  (ceramic resonator)
  Q1   3pin  C458 C    (BC458C, NPN transistor) (Ctrl+Amiga+Amiga)
  Q2   3pin  C458 C    (BC458C, NPN transistor) (CAPS LED)
  R1   2pin  47K Ohm   (for Q1 input/pullup) (Ctrl+Amiga+Amiga)
  R2   2pin  47K Ohm   (for HA17555 dis+thr)
  R3   2pin  1M Ohm    (for HA17555 trig) (Ctrl+Amiga+Amiga and power-up)
  R4   2pin  150 Ohm   (for Q2 output/limit) (CAPS LED)
  R5   2pin  22 Ohm    (for DRV GRN LED)
  R6   2pin  22 Ohm    (for PW RED LED)
  R7   2pin  120K Ohm  (for 74LS123 first RC)   brown-red-yellow ??? 120K ?
  R8   2pin  10K Ohm   (for 74LS123 second RC)
  R9   2pin  47K Ohm   (for 74LS123 first trigger)
  R10  2pin  100 Ohm   (for Q2 input/limit) (CAPS LED)
  C1   2pin  1nF       (for KCLK signal)
  C2   2pin  1nF       (for KDAT signal)
  C3   2pin  22uF 16V  (for 40pin IC supply)
  C4   2pin  100nF     (for 40pin IC supply)
  C5   2pin  10uF 16V  (for HA17555 dis+thr)
  C6   2pin  100nF     (for HA17555 supply)
  C7   2pin  100nF     (for 74LS123 supply)
  C8   2pin  100nF     (for HA17555 cv)
  C9   2pin  100nF     (for HA17555 trig) (power-up reset?)
  C10  2pin  1uF 16V   (for 74LS123 first RC)
  C11  2pin  100nF     (for 74LS123 second RC)
  C12  2pin  10pF      (for Y1 clock)
  C13  2pin  10pF      (for Y1 clock)
  C14  2pin  not installed (for 40pin IC supply)
  D    4pin  PW RED    (power LED)  (two diodes in series for "wide" light)
  D    4pin  DRV GREEN (floppy LED) (two diodes in series for "wide" light)
  FB1  2pin  not installed (alternately uses only a simple wire)
  FB2  2pin  not installed (alternately uses only a simple wire)
  FB3  2pin  not installed (alternately uses only a simple wire)
  FB4  2pin  not installed (alternately uses only a simple wire)
  CN   8pin  Connector to Amiga Mainboard
  CN  31pin  Connector to Keyboard Membrane (including CAPS LED)
  membrane key resistance is 190 ohm

[prowler]

Good work, nocash!

[Lonewolf10]

Agreed, thanks for sharing

Arrived looking for this exact info, and I found another invaluable work by Nocash, thanks!

The reset handling circuit schematics has 2 errors at least if I compare this schematics with my A500 rev 3 Amiga that is equipped with an early single pcb (no flat cable connector) keyboard made by HiTek.

The 74LS27 port used to check CTRL + C= + A combination press has to be swapped with the one checking for watchdog on /Y15 and the Q1 npn has E and B swapped.

Anyway thanks so much to author since this schematics has been precious to debug my dead keyboard.
Thanks,
wizy

[voxel]

good work nocash ^^)

btw, the two attachments you list on the first post aren't downloadable, all I get is an error message calling the admin... :-(

[demolition]

Originally Posted by wizy

The reset handling circuit schematics has 2 errors at least if I compare this schematics with my A500 rev 3 Amiga that is equipped with an early single pcb (no flat cable connector) keyboard made by HiTek.

In my experience, a keyboard from a Rev 3 A500 is not fully compatible with the later revisions motherboards. All the keys work individually, but Ctrl-A-A does not, so they changed something in relation to the reset signal.

Originally Posted by demolition

In my experience, a keyboard from a Rev 3 A500 is not fully compatible with the later revisions motherboards. All the keys work individually, but Ctrl-A-A does not, so they changed something in relation to the reset signal.

well actually everything looks absolutely the same just 2 of the 3 NOR of 74LS27 are swapped and I must say that in nocash schematics Q1 is definitely wrong even for new keyboards since the trigger command of an npn used like a switch is on B pin making current on C and E flow or not.

As said unvaluable work in any case being the only schematics I could find and made me go on fixing my A500, I just suggest mods so that if someone in my situation will arrive here looking for schematics will start from a correct situation.

Is the gif version of this still available somewhere?

Originally Posted by nocash

I couldn't find a schematic for the A500 keyboard, so I've drawn one myself...

...

[modrobert]

Originally Posted by yorgle

Is the gif version of this still available somewhere?

I couldn't find the original image so created a few variants, see attached files.

Linux commands used to convert the ASCII text to images (requires ImageMagick).

Black PNG

convert -size 1000x2000 xc:black -font "FreeMono" -pointsize 12 -fill white -annotate +15+15 "@a500_keyboard_mitsumi_schematics.txt" -trim -bordercolor "#000" -border 10 +repage black.png

Black GIF

convert -size 1000x2000 xc:black -font "FreeMono" -pointsize 12 -fill white -annotate +15+15 "@a500_keyboard_mitsumi_schematics.txt" -trim -bordercolor "#000" -border 10 +repage black.gif

White PNG

convert -size 1000x2000 xc:white -font "FreeMono" -pointsize 12 -fill black -annotate +15+15 "@a500_keyboard_mitsumi_schematics.txt" -trim -bordercolor "#fff" -border 10 +repage white.png

White GIF

convert -size 1000x2000 xc:white -font "FreeMono" -pointsize 12 -fill black -annotate +15+15 "@a500_keyboard_mitsumi_schematics.txt" -trim -bordercolor "#fff" -border 10 +repage white.gif

Oh.. I was hoping for the schematic as a drawing-gif.... not the text as a gif.

As a sidenote, I've recreated this (mostly) in KiCad. PDF is attached. I also have the two-connector version of the keyboard which i need to transcribe next.

I'll be putting these up on github, once i'm happy with them.

Note: this is not complete. Some of the power caps are not in place, and there are some arrangement issues i have with it right now. Comments, corrections, etc are welcome.

@nocash -- btw, thank you! I (and i'm sure others that are reading this) greatly appreciate your work on this... and I appreciate your work on all of your emulation ports I've used. ) Cheers to ya!

And here is the repository: https://github.com/BleuLlama/AmigaSchematics

For now it only has the 500 Mitsumi (one edge connector) schematic, but I have the older one with two edge connectors which I'll capture and document at some point.

Originally Posted by yorgle

I'll be putting these up on github, once i'm happy with them. Cheers to ya!

[breech]

Thanks, much appreciated

[solarmon]

Thank you to yorgle for the schematics which helped me a lot when putting this together, and for when troubleshooting and fixing my A500 keyboard!

I would have liked the keyboard membrane board layout to be in amigapcb.org and was looking for something similar, but could not find anything.

The people with hardware keyboards solutions would already have such a board layout design, but I can't find anything that is available to view and download.

So I have created a yEd (https://www.yworks.com/products/yed) diagram of the Mitsumi A619A membrane:



The master/source .graphml file can be found at:

https://github.com/solarmon/Amiga-Ke...itsumi%20A619A

It is best viewed in yEd so that you can select/highlight the links and follow the traces.

[ReadOnlyCat]

For those who may be interested, I have updated the schematics a little bit:

• Updated to Kicad5 (this converted internal library references to global ones).
• Replaced the existing connector with a standard one from the Kicad library and tagged with the labels used by Commodore for the A500 schematics.
• Fixed some signals inputs/outputs which were showing as bidirectional (strangely they were fine in the image posted in a previous post but wrong in the Kicad file).
• Renamed some labels to match the ones used by Commodore in the A500 schematics.
• Moved the status LEDs circuitry into its own functional block to lighten the page.

All in all, these are very minor changes the main goal was for the schematics to better match the official Commodore terminology so there is no risk of confusion.
I guess it would be nice if this page was integrated to the A500 schematics listed at http://www.amigawiki.org/doku.php?id...ice:schematics.

Originally Posted by yorgle

And here is the repository: https://github.com/BleuLlama/AmigaSchematics

I created a pull request from my fork of your repository so you could integrate these changes.
My repo is available at https://github.com/nekoniaow/AmigaSchematics but I would encourage anyone to work from yorke's repository though to avoid fragmentation. I do not plan to make any more changes beyond this point.

[solarmon]

@ReadOnlyCat,

I think there is a labelling error on the previous version and it does not seem to be corrected in this new version:

On pin 15 of the keyboard MCU you have it labelled as "PC5_Y6" but I believe it should be "PC5_Y5"?

[ReadOnlyCat]

Originally Posted by solarmon

@ReadOnlyCat,
I think there is a labelling error on the previous version and it does not seem to be corrected in this new version:
On pin 15 of the keyboard MCU you have it labelled as "PC5_Y6" but I believe it should be "PC5_Y5"?

You are absolutely correct.

I have fixed that and while I was at it renamed the 6570 pins to their proper MOS names and added the usage labels at the wire/pin junctions instead. Also renamed a few symbols to match (https://www.amiga-stuff.com/hardware/6500_1.html) and to those used in corresponding Commodore schematics.

It looks like there should be no need for additional changes this time.

The Kicad files are still at https://github.com/nekoniaow/AmigaSchematics and I will be creating another pull request to yorge's repository after sending this post.