Percom AT88-S1PD - 3.5"drive install? SD-X read FAT12?

[Xebec]

 

Oh sure; I get the love of tinkering. I just ordered a Happy repro board from Atarimax last night. I'm gonna park it in one of my 1050's and faff around with floppies again just ... because.

 

Hahaha very nice.. I just completed months of recovering old floppies, and then had a second wave of fooling around after upgrading some 1050's to USDoubler speed.. I'd like an 810 happy again some day..

[Xebec]

Can the side2 avoid using sdx? I am looking at one for a bbs and it will not run on sdx but I like the speed I have seen in the demos on YouTube.

 

So the SIDE 2 has a switch on the front, Down = boots into SD-X. Up = boots into it's own loader that lets you boot into it's own loader.

 

I don't know which other DOSes can use the storage on the SIDE 2 directly, but I do know if you have a SIDE2 and U1MB there is some way to make the SIDE2 and U1MB mount multiple .ATR files, which may suit your BBS needs.. Around 3:45 it shows this functionality:

[Bryan]

Good to know - thanks!

 

My concern was based on things like camera flashes that disable raspberry pi's because of ICs being very light sensitive. I assumed the old EEPROMs were pretty easy to clear as well.

EPROMS have 2 main retention factors: Exposure to light, and time since programming. Erasure is an intensity vs time situation so an uncovered (or partially covered) EPROM will lose data before a covered one if some amount of UV light is present. Electrons are trapped in the bit cells to set the data (well, to make a '0' cell) and these will leak over time leading to "bit-rot" after a few decades. Erasing helps all the electrons escape and re-programming the chip resets the clock (supply of electrons).

[+DrVenkman]

 

So the SIDE 2 has a switch on the front, Down = boots into SD-X. Up = boots into it's own loader that lets you boot into it's own loader.

 

 

FYI, Jon's (flashjazzcat's) "alternate" BIOS and loader are SO much nicer and easier to use than the one that ships with the U1MB! Using .ATRs is nice but I see what moonlight_mile is after, I think - accessing the CF-based PBI hard drive partitions in the U1MB from other DOS's. I don't know if that's possible, given how tightly Jon's PBI code integrates with the SDX environment.

[flashjazzcat]

My PBI code doesn't integrate specifically with SDX at all Herb - just the OS. So you can use the U1MB/SIDE PBI setup with any DOS which supports hard disks.

[+DrVenkman]

My PBI code doesn't integrate specifically with SDX at all Herb - just the OS. So you can use the U1MB/SIDE PBI setup with any DOS which supports hard disks.

 

Really? Fascinating!

​From a practical standpoint, how would that work? If the U1MB's internal SDX is set to off, and a SIDE2 cart is used with the switch UP, then the computer will boot into the SIDE loader, right? Is it possible to boot a SIDE2 cart without SDX and without going into the loader?

[Kyle22]

You don't need the Loader for what you want to do. Run FDISK and partition the drive, then boot whatever DOS you want and format the partitions.

 

It really is that easy.

[+DrVenkman]

You don't need the Loader for what you want to do. Run FDISK and partition the drive, then boot whatever DOS you want and format the partitions.

 

It really is that easy.

 

The point is, how do you use a SIDE2 cart without SDX loading from the cart (switch down) or the Loader loading (switch up)?

[flashjazzcat]

The U1MB PBI BIOS suppresses the SIDE cart ROM.

Edited August 13, 2017 by flashjazzcat

[+Larry]

Hi Jon-

 

Noticed this about the Side2 and your alt firmware. Does your firmware now allow MyDos (etc.) to actually use the XL/XE rom PBI, -or- is this a use of "soft drivers" when used with Dos other than SDX? I'm asking because it isn't quite clear to me, and (I think) I remember you indicating previously that actual use of the PBI is not possible except with SDX. (IIRC) (I don't remember the "why" it was not possible.) And if you have now figured out a way to do it, that's great! Thanks!

 

-Larry

[moonlight_mile]

 

FYI, Jon's (flashjazzcat's) "alternate" BIOS and loader are SO much nicer and easier to use than the one that ships with the U1MB! Using .ATRs is nice but I see what moonlight_mile is after, I think - accessing the CF-based PBI hard drive partitions in the U1MB from other DOS's. I don't know if that's possible, given how tightly Jon's PBI code integrates with the SDX environment.

Thanks for the info.

 

Sadly, I don't have a u1mb and I know all my chips are soldered down to my 130xe's board. So I am not confident enough to take on the task of installing it and there isn't anyone close that I know of that can install it or would have any knowledge to repair it if something went wrong.

 

That's why I am really looking for an external solution. The Sio2sd isn't slow by any means. I got it pretty fast. But I still would like to use a cart or a pbi interface solution.

 

No other ideas?

[flashjazzcat]

Does your firmware now allow MyDos (etc.) to actually use the XL/XE rom PBI, -or- is this a use of "soft drivers" when used with Dos other than SDX? I'm asking because it isn't quite clear to me, and (I think) I remember you indicating previously that actual use of the PBI is not possible except with SDX. (IIRC) (I don't remember the "why" it was not possible.) And if you have now figured out a way to do it, that's great! Thanks!

The U1MB PBI BIOS has been usable with any DOS since I wrote it back in 2011 or so and I would never have said otherwise. Indeed, I've tried to make it as clear as possible that it's not dependent on SDX at all... clearly I failed there.

 

It's the "soft drivers" which rely on SDX since they're loaded from the cartridge (you can't boot the drivers from the HDD since the computer can't talk to the HDD until the driver is loaded). With U1MB, the soft drivers are totally unnecessary: they're intended for HDD use with a stand-alone SIDE cart.

 

Not only can you use the PBI HDD with any DOS, but FDISK and other tools on the APT toolkit disk also work with any DOS. The version of FDISK on the SDX CAR: ROMdisk is just the standard Atari executable split into three chunks plus a small COM loader stub.

[+Larry]

Thanks, Jon. Searching at AA under "Pbi emulation" you said the same thing in 2013. Hey, you're consistent!

[DavidMil]

Looking through the AtariMax Percom AT-88 manual. I noticed that the schematic is missing. I have the schematic for the two

drive controller board if anyone is interested. The chip designators are different from both the boards mentioned in this strand.

However it still doesn't give any info about the center tapped transformer. I also have the 050-1290-001 manual for Atari drives.

 

DavidMil

[RodLightning]

Hi, I measured the transformer output on my Percom AT88-SPD floppy drive unit. It's a center tap 15 volt AC. I can't tell from your pictures what the power input looks like on the one you have. Mine has a 3 prong male connector on the board. The center is neutral with 7.5 VAC on each outer pin. A slightly different model here, but could be the same power supply?

[DavidMil]

Hi, I measured the transformer output on my Percom AT88-SPD floppy drive unit. It's a center tap 15 volt AC. I can't tell from your pictures what the power input looks like on the one you have. Mine has a 3 prong male connector on the board. The center is neutral with 7.5 VAC on each outer pin. A slightly different model here, but could be the same power supply?

 

I was thinking that it had to be somewhere between 14 and 18 volts because it needed to supply 5 and 12 volts to the drive and 5 volts to the chips also.

Thanks for verifying that! I've also attached the schematics for a Percom AT88 two drive controller board. The chip designations in the schematics don't

match any of the silk screen numbers on either of the two controller boards that are pictured in this thread, but the chips themselves are almost all the

same.

 

David

Percom Atari 2 Drive Controller Schematic.pdf

[redman]

I have 2 Percom AT88-S1PD drives. They both came with one 180K single sided drive. One now has 2 3.5" 720K drives

and the other is empty. I took pictures so you can see what they are like. Once I got the 720K drives to fully format, I put

a label on top of the drive because I surely would have forgotten how to do it again:) You can see from the screen shot,

using MyDos 4.53 enables you to have 2867 free sectors after formatting.

So yes, you can get 720K of usable space. I used 2 standard 720K DD drives from IBM pc's. They are a good choice

because they have drive select jumpers. You can probably use a 1.44 drive, but their drive selects are set to 1. The first

drive in a multi-drive setup has to be set to 0. Some 1.44 drives have selects and some can be modified to change drive

numbers. To clarify this, if you use one 1.44 drive, it will show up as drive B not A. You also have to use 720K DD floppies,

not 1.44's. There's a lot of discussion about 720 & 1.44 drive swapping out there.
I don't know anything about playing with FAT12 on an Atari. Hope this helps.

I just noticed that the drive on the left is wrongly marked 1/3. That was from a different project.

redman

 

[RodLightning]

...So yes, you can get 720K of usable space. I used 2 standard 720K DD drives from IBM pc's. They are a good choice

because they have drive select jumpers. You can probably use a 1.44 drive, but their drive selects are set to 1. The first

drive in a multi-drive setup has to be set to 0. Some 1.44 drives have selects and some can be modified to change drive

numbers. To clarify this, if you use one 1.44 drive, it will show up as drive B not A. You also have to use 720K DD floppies,

not 1.44's. There's a lot of discussion about 720 & 1.44 drive swapping out there.

I don't know anything about playing with FAT12 on an Atari. Hope this helps.

I just noticed that the drive on the left is wrongly marked 1/3. That was from a different project.

 

redman

Very cool setup. I once tried a 1.2mb 5.25in drive mech in my AT88 with no success. Currently running a double sided, double density IBM half height mech.

In the past, I had a single sided, full height mech, also running fine. I haven't tried a 3.5in floppy yet, but I'd like to some time.

I'm guessing any 3.5 floppy capable of running properly in a Atari ST would also work with Percom controllers.

[Xebec]

I have 2 Percom AT88-S1PD drives. They both came with one 180K single sided drive. One now has 2 3.5" 720K drives

and the other is empty. I took pictures so you can see what they are like. Once I got the 720K drives to fully format, I put

a label on top of the drive because I surely would have forgotten how to do it again:) You can see from the screen shot,

using MyDos 4.53 enables you to have 2867 free sectors after formatting.

 

So yes, you can get 720K of usable space. I used 2 standard 720K DD drives from IBM pc's. They are a good choice

because they have drive select jumpers. You can probably use a 1.44 drive, but their drive selects are set to 1. The first

drive in a multi-drive setup has to be set to 0. Some 1.44 drives have selects and some can be modified to change drive

numbers. To clarify this, if you use one 1.44 drive, it will show up as drive B not A. You also have to use 720K DD floppies,

not 1.44's. There's a lot of discussion about 720 & 1.44 drive swapping out there.

I don't know anything about playing with FAT12 on an Atari. Hope this helps.

I just noticed that the drive on the left is wrongly marked 1/3. That was from a different project.

 

redman

 

 

Awesome Redman - thank you!

 

Does the drive cabling have a twist / standard setup like a PC with two floppies then?

[redman]

 

Awesome Redman - thank you!

 

Does the drive cabling have a twist / standard setup like a PC with two floppies then?

 

No. The cable is straight.

 

First to avoid confusion, let's talk about floppy (PC type) drives and drive select

numbers (DS). The drive select number is set by putting a jumper on 2 pins at the

rear of the drive. Some drives are numbered DS1-DS4 while others are numbered D0-D3.

Some only have 2 DS's. 1.44meg drives usually don't have any jumpers while some of

them have 1 jumper. 720K drives usually have 4 DS's. So when I refer to the first

drive, it may be jumpered D0 or D1 and the second may be D1 or D2 based on it's numbering

system.

 

IBM set all their drives to be the second drive. Then they put 2 connectors on

the floppy cable with the cable twisted between them. The twisting changed the

location of certain wires so the floppy controller saw the drive at the end of the cable

(past the twist) as the first drive. The drive in the middle of the cable was seen as

the second drive. Now when you put a new drive in your PC, you didn't have to deal with

drive jumpers. The location on the cable determined whether it was Drive A or Drive B.

A lot easier than playing with tiny jumpers that get lost very easy.

[RodLightning]

I wish they had stuck with jumpers or even better, switches for selecting drive number...always hated making those twisted cables.
The IBM half height 5.25in drive I'm using has a D0-D3 jumper block. It runs as D0 by itself on the Percom controller. The older full height model I used before also had jumpers.

If I remember correctly, I tried a Toshiba HD 1.22mb floppy years ago and it didn't work when set as D0 or D1.
There are a few 3.5in 1.44mb high density drive models that have a solder blob that must be moved to change drive select.
I'm wondering if those are candidates for the Percom. I have personally come across two 3.5in HDD floppy drives so far with a switch (or jumper) to change drive number and can confirm they do exist..just less common.

[Xebec]

 

No. The cable is straight.

 

First to avoid confusion, let's talk about floppy (PC type) drives and drive select

numbers (DS). The drive select number is set by putting a jumper on 2 pins at the

rear of the drive. Some drives are numbered DS1-DS4 while others are numbered D0-D3.

Some only have 2 DS's. 1.44meg drives usually don't have any jumpers while some of

them have 1 jumper. 720K drives usually have 4 DS's. So when I refer to the first

drive, it may be jumpered D0 or D1 and the second may be D1 or D2 based on it's numbering

system.

 

IBM set all their drives to be the second drive. Then they put 2 connectors on

the floppy cable with the cable twisted between them. The twisting changed the

location of certain wires so the floppy controller saw the drive at the end of the cable

(past the twist) as the first drive. The drive in the middle of the cable was seen as

the second drive. Now when you put a new drive in your PC, you didn't have to deal with

drive jumpers. The location on the cable determined whether it was Drive A or Drive B.

A lot easier than playing with tiny jumpers that get lost very easy.

 

Perfect info - thank you!

 

Maybe I will try an old ST 720KB drive in this Percom controller to see how well it works.. I'm somewhat avoiding floppies for now, but using 720KB 3.5" floppies seems like it'd be pretty awesome.. I suppose the only downside is there is no way to accelerate the Percom to be as fast as a US Doubler drive..

 

Thanks again Redman!

[+Larry]

Here is a slightly better (I think) PDF of the Percom article from AC. I took my original mag and scanned it this AM.

 

-Larry

Percom Primer from Atari Classics 03-95.pdf

[DavidMil]

I thought it was 9v but don't hold me to that. But one thing I notice is you don't have a western digital drive controller chip/board. Did you remove the board that fits in that chip socket?

 

Yesterday I came across this board below and it seems to fit into the first board we have been talking about. See how it fits into the larger board.

Also the caps on the larger board that are under the smaller new board are bent over slightly, whereas the other caps on the lager board are all

straight up. My only concern is that both boards have different crystals on them, but the smaller board definitely has the missing WD controller chip.

 

David

Edited February 5, 2018 by DavidMil

[flashjazzcat]

Deleted.

Edited February 5, 2018 by flashjazzcat