• Please review our updated Terms and Rules here

Altos ACS8000

A

ArchaicAmusements

Member
Joined
Dec 22, 2010
Messages
25
Location
United Kingdom
I recently got an Altos ACS8000 with "Simpelec" branding. It has dual SA800 (one is a SA801 configured as an 800) floppy drives and the Altos 8200 motherboard (with DMA controller). I've been playing around with it over the weekend and I've got it booting to the monitor (v2.01). The monitor merely states "ALTOS COMPUTER SYSTEMS, Monitor ROM v2.01, Insert disk in drive 0 for autoload". Now I've checked all the PSU rails and everything is spot on, the machine has a full 208K of ram (or so I gather) and has all 3 SI0 chips so other than the FPP (optional) it's "maxed out". When it boots, Drive 0's activity led goes red constantly (empty drive) and it just sits there (no further console out) is this to be expected? (I'm sure the cables are ok - it reminds me of when you wire a floppy drive cable upside down :( ). Basically I would like some disks for this system (physical or images). The system is badged on the back as an 8000-7E but I also have the delivery receipt that says 8000-6 and also 8000-5+HD controller so I don't know what model it actually is. The SA800 drives appear to both be SSDD but I have no way to test them for now. I've looked around on the internet but I can only find images for later models (the -14). Any information would be great and disk wise anything that will run on it would be greatly appreciated. I've never used a machine with 8" drives before and I'm wondering if I can write my DSDD (Imation/3M - if it matters) media in these SSDD drives? I should also say this is a 230v 50Hz system and I don't know anything about its history. Thanks for your time.
 
Check the +24 power supply for the drives. Since the spindle motor is AC line powered, the fact that the disk is spinning means nothing. You should hear a solid "clunk" when the drive accessed as the heads load. If you don't, suspect the +24 supply.

Also note that the ACS8000, IIRC, has the drives inverted, so you insert your floppies "upside down".
 
Chuck(G) said:
Check the +24 power supply for the drives. Since the spindle motor is AC line powered, the fact that the disk is spinning means nothing. You should hear a solid "clunk" when the drive accessed as the heads load. If you don't, suspect the +24 supply.

Also note that the ACS8000, IIRC, has the drives inverted, so you insert your floppies "upside down".
Click to expand...

I have checked the 24v and it was spot on, I haven't actually put disks (nor do I have any system disks) in it yet. I have tried moving actuator motor manually to see if it would try to seek track 0 and move the head back but it just sits there. It seems strange to me that the activity light is solidly lit (it isn't if I disconnect the control cable so something must be going on). I've checked the data bus on the mainboard with my oscilloscope and the cpu is executing something (polling the dma controller perhaps?). Other than the spindle motors running and the activity light I get nothing else from the drives. How does the SA800 know a disk is inserted could I rig it to get it to attempt to read? I really wanted to know how the altos should behave while it waits for the disk. The monitor ROM goes no further than I said and my willem programmer doesn't do 2708s so I can't try and piece it together.
 
The SA800 won't do anything until a disk is inserted--it looks at the index pulse and derives a "drive ready" (pin 22, active low) signal, which gives the go ahead for the heads to load. The select line should be tied to the LED, so the stalling, waiting for a disk is understandable.

There's a good OEM manual for the SA800 on bitsavers.
 
Last edited:
The LED being on, sounds normal to me when it's looking for a disk.

Does your Altos have a metal front plate or a plastic one?

Their model numbering seems to have been changed as they went along - I think the early ones were the ones with the metal plate, and the weird model numbers.

I've got an Altos 8200-1 but you won't find that model number anywhere in their documentation.
It's got a metal front plate, is a multi-user system with the 8200 board, and needs/uses the DMA version of the software, on SSDD disks, and the disks go in upside down (ie: label down).
IIRC the A drive is on the right, and the B is on the left.

My other Altos is an 8000-1, has the plastic front plate, and the disks go in right side up (ie: label up).
This, I believe was a later version, when they'd gotten their model numbering sorted out, and they also relocated the A drive to be on the left, and the B drive on the right.

It's gets confusing - I only want one machine out at a time, and need my cheat (memory) sheet to make sure I've got everything right before I use one of them.

If you need some disks, I have both the DMA and the non-DMA versions.

Send me a PM , and we'll figure out what you need.
 
Yes it's the metal front panel model. Only the motherboard is badged as the 8200 which I got after looking at the user guide on bitsavers. It is the drive on the right that has the LED lit, I'm glad that sounds normal. The machine as I said earlier has SSDD drives (as far as I can tell at least) and the DMA controller is installed. I read about the upside down drives in the manual to and mine is one of those. The delivery receipt says it arrived in late 1981 so its a relatively early product (first few years). I have no idea what the Simplec branding is about and I can't find anything about it on the web. I've attached a picture of the machine as I got it, I've cleaned it up since then.

altos.JPG

EDIT:
I think I've got the DSDD disks to "read". I had to move the index hole sensor as these disks don't have the hole in the center. Now I get the headload solenoid going on and the actuator moving to track 0 so it seems to be attempting to read. Shortly after (5 seconds) the headload solenoid disengages. The disks I'm using are blank I'm just waiting on an FDADAP so I can write the images Lorne has given me.
 
Last edited:
I've got my FDADAP now and I'm using it with a pentium II machine with a 440bx chipset and some ITE super I/O chip. It supports 5.25" 1.2mb disks which is what I need? The disks I have are DSDD and the drive is a SA800 (single sided), I did move the index hole detector initially but now I've cut a new index hole in my disk (protected magnetic inner with paper and cut a rectangular hole out. The hope is that I can put the diagnostic image on one side and CP/M on the other (I have teledisk images as earlier mentioned. The computer is running DOS 5 on a IDE drive and is connected to the ALTOS's A: with B: disconnected. When I have the disk out I get a not ready error as I'd expect but with the disk in I get track 0 unusable/invalid media error. This happens when I try to format and when I try to write in teledisk. These are brand new disks but I have nothing I can test them in, I don't fancy paying to ship some proper SSDD disks from America as 8" disks are hard to come by here. When I try to write in teledisk the head loads and the FDADAP says it's on track 0 and then I get the error. When it boots it does try to scan the disk and runs through quickly (I can hear the heads moving) but I also get read errors in DOS when I try to dump the disk it's almost as though the computer isn't listening to the data coming from the disk. Any ideas? I don't know what to try next.
 
All 8" disks are high-density. If you're going to mimic the operation of an 8" drive with a 5.25', you'll need high-density media, regardless of the capacity or sided-ness of the original 8" media.
 
Okay, I think I understand.

Exactly what error does Teledisk give you? It's pretty specific. And (I'd have to check my collection) doesn't the ACS8000 use an FM (single-density, if you will) boot track? If my memory's not failing me, your floppy controller must be able to handle FM--not all do, but fortunately, there are simple tests to run.
 
Attempting to format in DOS gives me "Invalid media or Track 0 bad -disk unusable" and Teledisk gives me "Error reading A: - Sector not found Cyl 0, Side 0 Sect 1". If I take the disk out I get a drive not ready error. Like I said I'm using double sided media (soft sectored) with a new index hole cut out and I've lined up the photosensor by eye so it shouldn't be that. My ACS8000 has the 8200 board which is apparently the MFM one, the SA800 is a double density drive? The index hole I cut was rectangular and not circular, will this matter? I know it lines up fine with the detector in the drive. Thanks.
 
Drives are neither single- nor double-density (not to be confused with high density, which is something different). The difference between single- and double-density lies in the controller and is merely a different modulation method.

However, it sounds as if your controller is not single-density capable. If you have a 3.5" 1.44M drive, you can use this to see if your controller can handle FM.

Teledisk is saying that it sees the drive ready, but that 2 index holes have gone by without seeing the header for the indicated sector. Clearly, if your non-FM capable controller is spewing garbage instead of properly-encoded data that will be a problem.

One last thing--apologies for being obvious--are you using soft-sectored 8" media? Hard-sectored media has 33 index holes punched in it; soft-sectored has only one.
 
I'm using soft sectored media, the images I want to write are double density: I got from bitsavers. So it shouldn't matter if my controller can't do single density? What exactly do you mean by header? I was told to set my bios to 5.25" high density to use 8" double density disks, is this correct? My SA800 is the LSI version and the manual I have for it isn't clear about jumper settings. I'm pretty sure my Altos is an MFM version as the manual says the 8200 board is double density capable.
 
Capable, yes, but it's not uncommon for an 8" DD disk to have a single-density boot track with the remainder of the disk double. This allows the system to tell you that if you have a single-density controller, that you've got the wrong configuration.

I assume that you're getting your images from Herb Johnson's Retroarchive. Which file are you trying to work with? I'll download it and check it out.
 
I'm trying the diagnostics disk first " A8DIADMA.TD0" as I linked to bitsavers. Should I be able to format the drive in DOS? I've had the drive running on other machines and they would attempt to format it etc. I have a feeling its something to do with the jumper settings on my drive as the other drive - an SA801 behaves differently and only says "Drive not ready". The Pentium II machine I'm using has this motherboard. Lorne assures me those images are fine and the ones I need. The main thing I want to know is if my hand cut index hole window will work fine as the double sided disks had the window in a different place. How hard is it to align the heads on these drives I do have a scope?
 
Last edited:
I just looked at those images. It seems to me that we've had a similar question in the last week or so on cctalk--and the answer stays the same.

The ACS8000 double density disks use 128-byte MFM sectors--48 of them per tracks. Almost all PC floppy controllers choke on this--the only floppy controllers that can handle this oddball format are those which employ the National Semi DP8473 chip. You'll almost never encounter this chip on a motherboard, but it's present on several combo SCSI/MFM/ESDI hard disk "combo" controllers.

I sold Lorne an UltraStor 14N, which has this controller, but if you have, say, an Adaptec AHA1452B SCSI controller, that will also work, as will some Future Domain and DTC controllers.

The other alternative for you is to format your floppies in single-density to get things going. Herb's Retroarchive has the diagnostic in single-density here, but your floppy controller must be capable of single-density operation.

Hope this clears things up.
 
Chuck(G) said:
I just looked at those images. It seems to me that we've had a similar question in the last week or so on cctalk--and the answer stays the same.

The ACS8000 double density disks use 128-byte MFM sectors--48 of them per tracks. Almost all PC floppy controllers choke on this--the only floppy controllers that can handle this oddball format are those which employ the National Semi DP8473 chip. You'll almost never encounter this chip on a motherboard, but it's present on several combo SCSI/MFM/ESDI hard disk "combo" controllers.

I sold Lorne an UltraStor 14N, which has this controller, but if you have, say, an Adaptec AHA1452B SCSI controller, that will also work, as will some Future Domain and DTC controllers.

The other alternative for you is to format your floppies in single-density to get things going. Herb's Retroarchive has the diagnostic in single-density here, but your floppy controller must be capable of single-density operation.

Hope this clears things up.
Click to expand...

I still don't think that the disk format is the problem. I've tried testfdc that comes with image disk and I get NoAdrMark errors. The drive does respond to imagedisk and the actuator moves in both single and double steps. I'm wondering if the drive is out of alignment?
 
Chuck(G) said:
the only floppy controllers that can handle this oddball format are those which employ the National Semi DP8473 chip. You'll almost never encounter this chip on a motherboard, but it's present on several combo SCSI/MFM/ESDI hard disk "combo" controllers.
Click to expand...

Just adding that the Adaptec 1522 has a DP8473V chip and the 1522A has a DS8473AV. Dave Dunfield's site has a document pcfdc.txt that lists many floppy controllers (including motherboards) that have been tested and shows what formats they can handle. The Adaptec 1522A is one of the best at handling different formats.

http://www.classiccmp.org/dunfield/img63549/pcfdc.txt
 
Last edited:
You must log in or register to reply here.
Back
Top