davidc@pyr.gatech.EDU (David Carter) (10/25/89)
In article <4178@blake.acs.washington.edu> dlarson@blake.acs.washington.edu (Dale Larson) writes: >...BEWARE PROGRAMMERS BEARING SCREWDRIVERS AND SOLDERING IRONS!... and tells how he tried to get a 2000 keyboard to work on his 500, and eventually gave up. No offense intended (really!) but please leave hardware hacking to experienced hardware hackers! And let this be a warning to people who would try this kind of project: if you're not completely competent with screwdriver and soldering iron, give it to somebody else who is, or forget it. I really hate it when I hear somebody has fried their computer by accident. [A condensed version of this article, along with the pin connections to use a 2000 keyboard on a 1000 and vice-versa, would probably be a good thing to add to the monthly comp.sys.amiga.tech newuser posting. Anyone else agree? Who do I tell?] The usual disclaimers about voiding warranties and "It's not my fault if you torch your Amy" apply here. Also, Commodore may change their design at any time, making this information inaccurate for new machines. The Amiga 500 and 2000 keyboards are nearly identical! If you don't believe it, open up one of each and compare them side-by-side as I have. They are the same printed circuit board. There =are= two different =styles= of keyboards, one with a membrane array, and the other with individual keyswitches. But the circuits themselves are identical. Both 2000s and 500s have come with both types of keyboards. Quick way to tell the difference: you can see a metal rivet-like thing between the Del and Help keys on the keyswitch style. I can also tell by the feel (the membrane style is "mushier"). I have taken a 500 keyboard and used it on a 2000 (with 'control-Amiga-Amiga' reset working perfectly) and a 2000 keyboard on a 500 (my current setup, again with reset working perfectly). There are two small differences in the keyboards: The 500's has one extra transistor, type 2N3904 at position labeled Q1. The 2000's has empty holes at this position. If you want to use a 2000 keyboard on a 500 and want reset to work, you must add this transistor. Doing so sends the reset signal to pin 3 on the DIN plug (yes, there is an extra conductor in the coiled cord for this pin. It is a NC inside the 2000 computer). To use a 500 keyboard on a 2000, you must remove the transistor. The other difference is that the 2000 keyboard has empty holes where the "power" and "drive" LEDs would go on the 500. Unfortunately, there are no wires for these in the coiled cord. They are still a good thing to have, so you should think about getting some extra LEDs and mounting them somewhere in the A500's case. Here are the pinouts for the connectors: The 2000's Keyboard Plug is a male 5 pin DIN connector. The diagram here is looking at the solder side (back) of the female part -- what you'll have to buy to plug the keyboard into. On mine, the numbers are written on the plastic on the back, next to each pin. 2 5 4 Female 5-pin DIN socket, 3 1 looking at rear (solder pins) 6 Pin Signal Description --- ------ ----------- 1 KBCLK Keyboard Clock 2 KBDATA Keyboard Data 3 NC Not Connected (becomes Reset after adding transistor Q1) 4 GND ground 5 +5v +5 volt power 6 SHIELD shield The A500's connector is an 8 pin "molex type" connector (single row, 0.1" spacing). Looking at it from the front of the A500, pin 1 is the leftmost pin. KBCLK KBDATA RESET +5v NC GND Power Drive 1 2 3 4 5 6 7 8 NOTE: The A500 schematics in the "Introduction To The 500" and the "500/2000 Technical Reference" manuals INCORRECTLY show pin 1 as KBDATA and 2 as KBDCLK. "Power" and "Drive" go high (+5v) to light the two LEDs. So the cable you'll need to make (which I've been using in my A500 without any problems for nearly a year) looks like: molex plug DIN socket to into A500 2000 keyboard Signal 1 1 KBCLK 2 2 KBDATA 3 3 RESET 4 5 +5v Careful!! 5 - NC on A500 motherboard 6 4 gnd Careful!! 7 - Optional: "Power" LED 8 - "Drive" LED - 6 Shield ground from keyboard; connect to RF shield of A500 The other sides of the Power and Drive LEDs go through 220 ohm resistors to ground. The 500's LEDs are actually dual (two LEDs in series in a single plastic lens). So if you use single LEDs, you should probably use slightly higher resistors, like 680 ohm. One last note: Since the A500 uses a hard reset line (another long story), when you unplug or plug the 2000 keyboard to your A500, you will reset the computer (unlike on the 2000 computer). David Carter davidc@pyr.gatech.edu
pnelson@hobbes.uucp (Phil Nelson) (10/27/89)
In article <8279@cbmvax.UUCP> valentin@cbmvax.UUCP (Valentin Pepelea) writes: |In article <9451@pyr.gatech.EDU> davidc@pyr.gatech.EDU (David Carter) writes: | || No offense intended (really!) but please leave hardware hacking to experienced || hardware hackers! | |Oh? And just how does one become an experienced hardware hacker? | By wrecking one or more pieces of hardware ;-) |Valentin Phil Nelson at (but not speaking for) OnTyme:NSC.P/Nelson Tymnet, ?McDonnell Douglas? Network Systems Company Voice:408-922-7508 UUCP:{pyramid|ames}oliveb!tymix!pnelson LRV:Component Station My Amiga survived the "Quake of 89"!