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

[Bob and Bettina Groh]

I sort of wondered about the software side of things. I thought of adding a USB 
interface to the H89 but rapidly came to the conclusion that writing and 
debugging the software driver would be a major undertaking. Given how little 
work I get done anyways, the idea was put aside. Sounds like the IDE interface 
might fit in the same boat. Wish I knew more about it - it would be nice to be 
able to add some of the old hard drives to an H-89 et al.  Sigh.

Bob Groh

Lee Hart wrote:
> 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 
> mode.
> 
>> 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.

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