Heathkit H89A

From: Marvin <marvin_at_rain.org>
Date: Fri Dec 1 19:51:50 2000

Tony, you are incredible :)! Thanks, and I've printed out that info and will
stick it with the machine. From what I've heard, that chip is no longer
available and I am curious if it is worth the effort to make up a plug-in
replacement. This machine was marked "For Parts Only" but I really dislike
tearing apart these machines if something can be done to make it work. Has
anyone looked at making up a plug-in replacement, and/or has a machine that
also needs this chip? If there is enough of a demand, it might be a fun
project!

Tony Duell wrote:
>
> >
> >
> > I have a Heathkit H89A I acquired some years ago with a note attached "Bad
> > keyboard encoder on terminal card." Is anyone here familiar with the
> > keyboard encoder? I sort of recall reading somewhere that the keyboard
>
> Sure am....
>
> I have the Z90 manual here, which is essentially the same machine...
>
> The keyboard encoder is the 40 pin chip at location U444 on the terminal
> logic board. The terminal logic board is the large board standing
> vertically at the very back of the machine, and U444 is just above the
> connector for the keyboard ribbon cable.
>
> The keyboard encoder has the Heath/Zenith part number 443-913, and is
> described as an S470 keyboad encoder in the IC specifications list. I am
> told that there was a standard keyboard encoder with much the same
> pinout, but with different internal programming, so the output codes for
> some of the keys are different. However AFAIK, all H88s, H89s, Z90s and
> H/Z19 terminals use the same encoder chip, so if you find a dead example
> of any of those machines, it's a possible source of the chip.
>
> The output of the keyboard encoder chip goes to a ROM, U445 (444-37) on
> the terminal logic board. This translates the keyboard codes into ASCII
> (and special codes for the non-standard keys). Whether you could use a
> standard encoder if you reprogrammed the ROM, I don't know.
>
> For reference, the pinout of the keyboard encoder chip is :
>
> 1 B3 (bit 3 output) (=A2)
> 2 Vll (ground)
> 3 clock input
> 4 X9 (keyboard scan output)
> 5 X8
> 6 X7
> 7 X6
> 8 X5
> 9 X4
> 10 X3
> 11 X2
> 12 X1
> 13 Data strobe output
> 14 Data strobe control
> 15 Output Enable
> 16 Repeat
> 17 Key bounce mask
> 18 Vgg (-12V)
> 19 Control key input
> 20 Shift lock I/D
> 21 Shift
> 22 Y10 (keyboard input)
> 23 Y1
> 24 Y2
> 25 Y3
> 26 Y4
> 27 Y5
> 28 Y6
> 29 Y7
> 30 Y8
> 31 Y9
> 32 Vss (+5V)
> 33 B5 (=A4)
> 34 B6 (=A5)
> 35 B7 (=A7, control output)
> 36 B8 (=A8, shift output)
> 37 B1 (=A0)
> 38 B2 (=A1)
> 39 B9 (=A6)
> 40 B4 (=A3)
>
> The B-lines are scambled before being connected to the ROM -- I've put
> the assignments in brackets above). A9 and A10 on the ROM are groudned.
>
> The address inputs to the ROM for each key are :
> f1 0a
> f2 2a
> f3 1a
> f4 3a
> f5 4a
> Erase 6a
> Blue 5a
> Red 7a
> Grey 06
> Esc 2d
> 1 05
> 2 25
> 3 15
> 4 35
> 5 45
> 6 65
> 7 55
> 8 75
> 9 0d
> 0 5c
> - 7c
> = 02
> ` 22
> Bsp 12
> Tab 79
> Q 51
> W 71
> E 09
> R 29
> T 19
> Y 39
> U 49
> I 69
> O 59
> P 44
> [ 64
> \ 54
> LF 74
> Del 0C
> A 4E
> S 6E
> D 5E
> F 7E
> G 01
> H 21
> J 11
> K 31
> L 41
> ; 18
> ' 38
> { 48
> Ret 68
> Scroll 61
> Z 16
> X 36
> C 46
> V 66
> B 56
> N 76
> M 0E
> , 2E
> . 1E
> / 00
> Space 3E
> K0 50
> K. 70
> Kenter 08
> K1 04
> K2 24
> K3 14
> K4 1C
> K5 3C
> K6 4C
> K7 42
> K8 62
> K9 52
> NU1 32
> NU2 40
>
> (K-prefixed keys are on the number pad)
>
> The outputs of the ROM -- i.e. what the firmware on the terminal logic
> card is expecting -- for each key are :
>
> key norm shift ctrl s&c
> f1 00 00 80 80
> f2 01 01 81 81
> f3 02 02 82 82
> f4 03 03 83 83
> f5 04 04 84 84
> Erase 05 05 85 85
> Blue 06 06 86 86
> Red 07 07 87 87
> Grey 0e 0e 8e 8e
> Esc 1b 1b 9b 9b
> 1 31 21 b1 a1
> 2 32 32 b2 b2
> 3 33 23 b3 a3
> 4 34 24 b4 a4
> 5 35 25 b5 a5
> 6 36 36 b6 b6
> 7 37 37 b7 b7
> 8 38 38 b8 b8
> 9 39 39 b9 b9
> 0 30 30 b0 b0
> - 2d 2d ad ad
> = 3d 3d bd bd
> ` 60 60 e0 e0
> Bsp 08 08 88 88
> Tab 09 09 89 89
> Q 71 51 f1 d1
> W 77 57 f7 d7
> E 65 45 e5 c5
> R 72 52 f2 d2
> T 74 54 f4 d4
> Y 79 59 f9 d9
> U 75 55 f5 d5
> I 69 49 e9 c9
> O 6f 4f ef cf
> P 70 50 f0 d0
> [ 5b 5b db db
> \ 5c 7c dc fc
> LF 0a 0a 8a 8a
> Del 7f 7f ff ff
> A 61 41 e1 c1
> S 73 53 f3 d3
> D 64 44 e4 c4
> F 66 46 e6 c6
> G 67 47 e7 c7
> H 68 48 e8 c8
> J 6a 4a ea ca
> K 6b 4b eb cb
> L 6c 4c ec cc
> ; 3b 3b bb bb
> ' 27 27 a7 a7
> { 7b 7b fb fb
> Ret 0d 0d 8d 8d
> Scroll 1f 1f 9f 9f
> Z 7a 5a fa da
> X 78 58 f8 d8
> C 63 43 e3 c3
> V 76 56 f6 d6
> B 62 42 e2 c2
> N 6e 4e ee ce
> M 6d 4d ed cd
> , 2c 3c ac bc
> . 2e 3e ae be
> / 2f 3f af bf
> Space 20 20 a0 a0
> K0 10 10 90 10
> K. 1a 1a 9a 9a
> Kenter 1c 1c 9c 9c
> K1 11 11 91 91
> K2 12 12 92 92
> K3 13 13 93 93
> K4 14 14 94 94
> K5 15 15 95 95
> K6 16 16 96 96
> K7 17 17 97 97
> K8 18 18 98 98
> K9 19 19 99 99
> NU1 0b 0b 8b 8b
> NU2 0c 0c 8c 8c
>
> While this might be more work than you want, the above should allow you
> to create something that will work...
>
> -tony
Received on Fri Dec 01 2000 - 19:51:50 GMT