Atari PCH204 help needed

[KLund1]

Hi Everyone,

Not sure if this is the right forum for this. It is for an Atari 8-bit computer, just not a 6502 based machine.

I have a working Atari PC1. All seems good with it. But I have a matching but sick Atari PCH204 Hard Drive unit. The actual drive that came with it, an Epson HMC-755 is completely dead. So I trolled ebay and found a similar sized drive, a Seagate ST351A/X. I've have jumppered it several ways and the PC1 will not recognize it. I do not get a 1701 error any more (as when the Epson was installed). But Fdisk from DOS 3.3 reports no fixed disk attached. The drive spins up fine. Perhaps this drive is just not compatible. But the specs show that it is ok for XT and AT uses. I'm assuming the PC1 is an XT clone with some internal upgrades from Atari. I was thinking I need to use the DEBUG command in Dos to low level format this HD, but I have no clue as to what parameters/switches to use. I have received some limited help from VintageComputers.com but nothing that really helps.

Any thoughts, suggestions or ideas?

Thanks

(I'm going to post this in the ST forum too)

 

[ricortes]

I have one of those Seagates. Jumpers on mine are

00XX0X

00000X

 

Haven't tried it on an PC/XT class machine in the last 25 years. The thing with the older XT class machines is they were 8 bit and mostly didn't contain IDE controller in BIOS so they included it on the card. Of course no one has any idea what Atari did.

 

*IF* there is no jumper setting to set the hard drive capacity/type on the motherboard you may have to do it from a low level format but there is no guarantee where the BIOS is located.

 

If it was me, I would just load DEBUG and start doing

DC800:0

DD800:0

...

and see if there is anything in what would be a PC type controller. At least on some cards it was possible to relocate where they appeared so you could eliminate address conflicts. But then being Atari, they may have had all the HD functions on floppy since that would be cheaper then a ROM.

If you find something, a good bet would be to G(o) C800:5 i.e.

GC800:5

 

but the starting point could be anywhere in ROM or as I said, could even load from disk. I have zero experience with 8 bit IDE controllers and Atari PCs so take anything I say with a grain of salt.

[KLund1]

Thanks for the reply.

Here are some pics, Can you compare the orientation of my jumpers to yours?

 

 

[ricortes]

Correct me if I am wrong but that is a 50 pin connector going in from the PC1>PCH204? It has to be buss signals/equivalent to a slot, but PC 8 bit slots are 62 pins. Anything to save a few cents.

 

Anyway, the wider 28 pin chip with a label on it is the ROM. The other chips are just address decode and buffers/transceivers. That's a good thing. I found a jumper setting for the 351, apparently I have mine set for slave drive and bus reset low. I have my pins upside down from the picture/GIF. It looks to me like your jumpers are correct. Only thing you may want to try is bus reset high jumper but I don't hold a lot of hope for that working.

 

The jumpers on the interface card nearest the PC1 are probably address decode for where the card is seen by the PC1. It could be setting drive capacity but I would not put money on it. IDE drives are supposed to be able to tell you their configuration. i.e. I have 4 heads and 800 cylinders.

 

So, I think you are back to trying to find out the address of the card using the PC1. With the interface connected boot DOS, go to DEBUG and just keep doing the

DC800:0

 

up until you find something other then zeros. Also check the pin polarity for the ribbon cable.

 

Maybe see if you can hook the HD up to an Intel/AMD box and see if it is recognized there. Be a shame if it is toast.

[KLund1]

SUCCESS!!!!!

With the above pic that showed the correct orientation of the drive to the PCB, and looking at many similar pages. I found one that showed XT mode with jumper 7-8 shorted. I got the PCH204 to live!! I did have change another jumper to bus reset high.

SEE PICTURES!!!

It boots from C:

And it runs GEM! but only from floppy. I copied all the GEM files to C, edited the .bat file, but I think some of the programs might be hard coded to A: to run.

I wish I had the real docs for this machine to get all the details about how to set it up.

[harlock]

does the ribbon cable from the pch204 just go into the removable slot plate on the back of pc1 and plug directly into the header on the board? from you pictures it sort of looks like it is an isa breakout box but i am stunned at the ide controller card with a 50 pin interface and 40 pins used, plus all those cut wires.

My 1st computer was a pc1 and i still have it packed away. i always lusted after a hdd for it but i really never know what the proper part was at the time. maybe i'll run across a psh204 chassis some time.

thanks

[dir_marillion]

Hi, I know that this thread is old but could you please inform exact which jumpers did you use, to make it work ?

 

Thank you

[+MrFish]

SEE PICTURES!!!

 

Now THAT would be the perfect keyboard to use with a Transkey II -- although I guess it's a pretty standard piece of hardware with an Atari sticker on it.

[KLund1]

Yes it would be. But it was difficult to find a close to mathcing PC1 keyboard. 9=pin Din XT keyboards are not cheap/easy to find.

[+MrFish]

OK, so it's not the keyboard that's supposed to come with the machine? I thought that logo was put on there by Atari actually. If not, it's less interesting to me.

 

I didn't realise those were so hard to find these days. Had I known, I wouldn't have dumped two very nice ones I owned when I moved a little over a year ago.

Edited August 26, 2015 by MrFish

[dir_marillion]

Hi,

I was wondering if you have checked the jumpers of the hard disk that make it recogznizable by Atari PC1.

 

Thank you