[sebhc] H-89 bus pin out Help

Lee Hart leeahart at earthlink.net
Tue Mar 14 21:35:03 CST 2006


bill malcolm wrote:
> Thanks for the info: Do you have exact pin out for the 25 pins?

Sure. Here they are. D0-D7 are the data bus, and A0-A15 are the address
bus. The control lines are active high, unless I put a slash before them
(i.e. /WAIT means wait when low).

H89 Memory expansion connectors (left side of board)
---------------------------------------------------
   P501, P502, P503	 1 = gnd
			 2 = D0
			 3 = D1
			 4 = D2
			 5 = D3
			 6 = D4
			 7 = D5
			 8 = D6
			 9 = D7
			10 = gnd

   P507, P508, P509	 1 = +5v
			 2 = gnd
			 3 = A0
			 4 = A1
			 5 = A2
			 6 = A3
			 7 = A4
			 8 = A5
			 9 = A6
			10 = A7
			11 = A8
			12 = A9
			13 = A10
			14 = A11
			15 = A12
			16 = MEM 0 (gen.pur.port, bit 4)
			17 = MEM 1 (gen.pur.port, bit 2)
			18 = /RD5 (decoded Read address strobe)
			19 = /RD6 (decoded Read address strobe)
			20 = /RD7 (decoded Read address strobe)
			21 = +12v
			22 = -12v
			23 = +5v
			24 = +12v
			25 = gnd

H89 I/O expansion connectors (right side of board)
-------------------------------------------------
   P504, P505, P506	 1 = gnd
			 2 = D0
			 3 = D1
			 4 = D2
			 5 = D3
			 6 = D4
			 7 = D5
			 8 = D6
			 9 = D7
			10 = gnd

   P510, P511		 1 = +5v
			 2 = gnd
			 3 = A0
			 4 = A1
			 5 = A2
			 6 = /BRD (buffered Read)
			 7 = /BWR (buffered Write)
			 8 = /WAIT
			 9 = /IO SER.0 (serial I/O select, port#0)
			10 = /IO SER.1 (serial I/O select, port#1)
			11 = /IO LP (serial I/O select, line printer)
			12 = /IO CASS (serial I/O select, cass.tape)
			13 = 2.048 MHz clock
			14 = 1.8432 MHz clock
			15 = /RESET
			16 = I/O.0 (gen.pur.port, bit 6)
			17 = I/O.1 (gen.pur.port, bit 7)
			18 = /INT3 (interrupt priority #3)
			19 = /INT4 (interrupt priority #4)
			20 = /INT5 (interrupt priority #5)
			21 = +12v
			22 = -12v
			23 = +5v
			24 = +12v
			25 = gnd

  P512			same as P510, P511 except for:
			11 = /IO FLPY (hard-sector controller select)
			12 = FMWEH (Floppy Memory Write Enable High)
-- 
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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