[sebhc] Re: Great Idea for IDE MORE!! STATUS -- chips used

Lee Hart leeahart at earthlink.net
Wed Sep 20 08:41:31 CDT 2006

bill malcolm wrote:
> HI:  this uses  the following chips
> 3  74hct32
> 1  74hct08
> 1  74hct04
> This design is not mine -- I found this used for the apple II & would
> be easy to use with the Z-80.

The parts count looks suspiciously low. The GIDE circuit worked out by 
Tilmann Reh is quite complicated, because it supports 8-bit and 16-bit 
IDE devices (and almost all IDE devices are 16-bit). The Z80 basically 
has to output the low byte, then the high byte, then the write command, 
saving each part in latches. The reverse needs to be done to read; issue 
the read command and capture the 2 bytes in latches, then read the low 
byte latch, then the high byte latch.

I have the circuit for Mike Riley's IDE interface for an RCA 1802 
computer. It uses 3 ICs; one 74LS32, one 74LS04, and one 74LS75 4-bit 
latch (for the command); but it requires IDE devices that support 8-bit 

> Boot code is needed  for this device

With the GIDE interface, it took *years* before anyone got around to 
writing any software to actually make it work. When they did, each 
person typically wrote a driver for their specific IDE device that did 
not work with any other. The market being what it is, almost no one else 
could find the same model hard drive, nor figure out the guy's code to 
modify it for something else.
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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