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8-bit Storage Relief

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Great Hierophant

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For those of us with 16-bit slot computers, adding a large amount of storage space is as easy as finding a finding a small hard drive and a 16-bit IDE interface card. Sound cards often came with IDE interfaces. But what about 8-bit computers? 8-bit computers seem to be stuck with slow MFM or RLL controllers, small-sized but heavy and less reliable hard drives, not to mention that they are noisy as hell. I think that implementing an 8-bit IDE interface would be relatively simple, using only TTL logic and relying on the drive to supply a BIOS. But they seem to be rare and expensive. What kind of relief/alternatives can be offered?
 
Hi,

I think you have two options for an IDE HD interface on an 8 bit CPU

1. GIDE, which is an excellent low part count design but uses custom programmable GALs. The KC computer club sells these kits and unless you can program your own GALs, I recommend going with the KC club solution.

http://www.gaby.de/gide/

2. Other IDE circuits which use more chips (about 10 total) but are commonly available 74LSxxx or 74HCTxxx parts such as

http://www.hanssummers.com/computers/cpcng/ide/index.htm

and related but different

http://www.retroleum.co.uk/z80-ideinterface.html

I recently built an IDE interface for my Test Prototype homebuilt computer. It has all the schematics, test software, and an all 8080 instructions CP/M 2.2 CBIOS already written for it.

The circuit is very simple in principle. Basically it is two latches which simulate a 16 bit interface on an 8 bit databus with glue logic to fill in the timing requirements. It is really no problem to build your own.

I attached a picture of my Test Prototype so you can see what I am referring to. The IDE interface is on the second card. It shares a 100x130 mm protoboard with a FDC circuit I am presently building so you can see it is not a big circuit board space wise.

Best of luck with your project! Thanks!

Andrew Lynch
 
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Great Hierophant said:
I need something that will work in an 8088-based PC, not a z80 machine.
Click to expand...

The GIDE probably is not going to work for you but the other circuits definitely will. Unfortunately, it most likely means you will need to write the drivers though unless someone has done them already. I have seen XT IDE adaptor plans so it is possible they are out there.

You would need to do some research to find them. I know that the 8-bit to IDE circuits have been made to work on 65xx, 68xx, 8080/8085, Z80 and other 8 bit CPUs but the 8088 I am not sure about.

Best of luck with your project!

Andrew Lynch
 
Great Hierophant said:
I need something that will work in an 8088-based PC, not a z80 machine.
Click to expand...

Wow. I thought that Andrew provided a wealth of information there, more than enough probably to get started building such an interface for an XT. Yes, you'd have to do a BIOS ROM or a software device driver, but more than enough information.

What are you looking for - part numbers of something you can buy? I actually appreciated the more detailed information. You apparently did not.


Mike
 
Great Hierophant said:
I need something that will work in an 8088-based PC, not a z80 machine.
Click to expand...

I knew I'd seen something like what you are asking about and here it is:

http://www.mylinuxisp.com/~jdbaker/oldsite/SmallSys/8bitIDE.html#XTIDE

Most likely though, unless someone has another idea, this solution is going to require making the interface yourself from parts. Fortunately, you are in luck since XT class prototype boards are commonly available and there is demonstration software available making the project a whole lot easier.

Best of luck with your project. I am willing to help to the extent I can but building on the 8088 is outside of my experience.

Thanks!

Andrew Lynch
 
Great Hierophant said:
I need something that will work in an 8088-based PC, not a z80 machine.
Click to expand...

Why not just get a SCSI card made for an XT? Very easy to run something like a 1Gb drive. With most of the XT IDE adapters you would probably have the 512Mb barrier.
 
I'm sorry, I didn't mean to be short with lynchaj, and his last link is almost just what I need. The only concern is whether it will work with DOS and Windows, because the driver is designed for Linux. But I think IBMMuseum may have the best suggestion, find an 8-bit SCSI combo instead of an IDE combo.
 
Great Hierophant said:
8-bit computers seem to be stuck with slow MFM or RLL controllers, small-sized but heavy and less reliable hard drives, not to mention that they are noisy as hell. I think that implementing an 8-bit IDE interface would be relatively simple, using only TTL logic and relying on the drive to supply a BIOS. But they seem to be rare and expensive. What kind of relief/alternatives can be offered?
Click to expand...

I use a Silicon Valley ADP-50; it's an IDE adapter that takes drives up to 500MB. I've got a Maxtor 340MB real IDE drive as master and an IBM CompactFlash II 340MB flash card connected to a CF-to-IDE adapter as the slave.

Alternatives?

  • 8-bit SCSI card, preferably with boot BIOS. Can go up to 2G without much trouble; higher with small trouble :)
  • Hardcards (like Plus HardCard 20 or 40) (although these are no faster than MFM, just more convenient)
  • 8-bit IDE/custom/soundcard CDROM interface and CDROM drive, if all you want to do is have a large stash of read-only data available (like games)
 
Great Hierophant said:
But I think IBMMuseum may have the best suggestion, find an 8-bit SCSI combo instead of an IDE combo.
Click to expand...

Although I already have an 8-bit IDE adapter, I too am (still) looking for an 8-bit SCSI adapter with a boot BIOS, as I am very curious to see just how fast I can stream data from the hard disk. Currently my maximum speed is 300KB/s, but mbbrutman has done faster with SCSI because it's memory-mapped.
 
Trixter said:
Although I already have an 8-bit IDE adapter, I too am (still) looking for an 8-bit SCSI adapter with a boot BIOS, as I am very curious to see just how fast I can stream data from the hard disk. Currently my maximum speed is 300KB/s, but mbbrutman has done faster with SCSI because it's memory-mapped.
Click to expand...
my max speed is 554 Kilobyte per sec
using 64M CF card on silicon ADP-50 8 bit IDE card (measured by norton SI)

the most advantage of IDE/CF system is noiseless.
a voiceless system could be builded if the XT power is also swaped with a DC-DC converter (the ones using in carPC).

--------
Lee
 
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I have a similar but differnt quesiton. Is there a way to interface an IDE drive to an MFM controller via some kind of adapter or bridge?
I have a 1985 Amiga MFM controller which I don't want to scrap since it's so rare, but I want the reliability of a 20-40MB CF card.
 
FastRobPlus said:
I have a similar but differnt quesiton. Is there a way to interface an IDE drive to an MFM controller via some kind of adapter or bridge?
I have a 1985 Amiga MFM controller which I don't want to scrap since it's so rare, but I want the reliability of a 20-40MB CF card.
Click to expand...
Not that I know of. Picture it like this, the MFM drives have controllers designed specifically for them. IDE drives have their own controllers on their circuitry. (like how CF cards do too)

If it is done, it's "probably" done by.........i honestly have no clue..
 
Why not just get a SCSI card made for an XT? Very easy to run something like a 1Gb drive. With most of the XT IDE adapters you would probably have the 512Mb barrier.
Click to expand...

I am an idiot and apologize for being so, I may have had the answer under my nose all the time (at least since the beginning of this post) and just didn't know it. I am the proud owner, at no small cost, of a Media Vision Pro Audio Spectrum. I bought this 8-bit sound card because it used a dual OPL2 configuration used by some games, but forgot that it had a 50-pin SCSI controller on it, using an NCR/Zilog 5380 SCSI controller. While obviously this drive was designed for CD-ROMs, could it be used to boot or at least access a SCSI hard drive? I guess it may not be able to boot, because it does not contain a boot rom, but should be recognizable after loading DOS from disk.

While I like the idea about using a CD-ROM, I see two difficulties. First, you have to obtain a SCSI or Panasonic (if I am going to use my Sound Blaster Pro 2) CD-ROM. Second, what if the game wants to write to the disk? I would have to copy the game to a floppy, of course, assuming it will fit onto the floppy.
 
On the subject of high capacity on an XT class (8-bit bus) machine, there are a handful of choices.

In my own XT machine I use an AIC (Advanced Information Concepts) SCSI controller with an old seagate ST-227N 60MB drive, and I still have not topped off that hard disk yet, even after throwing literally TONS of stuff on the hard disk. I also have a 2.1 GB and an 8GB Hard Disk as spares (now THAT is a lot of space for an XT!!).

Other solutions I considered were finding an 8-bit ISA Controller with a BIOS, or going back to my old dual RLL or a dual MFM Setup like I had in the clone before this machine (MFM and RLL came in as high capacities as 160 MB), or go with the short lived ESDI. But all those are a pain to get my hands on.

With the SCSI, I've been reading up on the Uncreative Labs forum lateley and there has been discussion of going "solid state" on XT's (using flash memory stuff). If I could learn enough about the internals, I'd love to learn to make a Solid State SCSI storage device, particularly clever would be making an "expandable" ojne (empty chip slots).

Not to veer off subject too much, but the Idea of a DIY IDE controller for a Tandy 1000 EX is another thing I've toyed with, using laptop hard disk drives so it all fits inside the Tandy itself. If I could only find a pinout of the bus on that thing.
 
Mad-Mike said:
Not to veer off subject too much, but the Idea of a DIY IDE controller for a Tandy 1000 EX is another thing I've toyed with, using laptop hard disk drives so it all fits inside the Tandy itself. If I could only find a pinout of the bus on that thing.
Click to expand...
The 1000ex bus is pin for pin compatible with the ISA 8 bit bus, minus a few signals.

Try downloading the EX tech reference from: http://www.oldskool.org/guides/tvdog/documents.html

I've built simple EX to IBM style adapters using headers, ribbon cable and female cardedge connectors.
 
@Mad-Mike

While I haven't seriously looked into designing my own SCSI to CF adapter, something is telling me that it's probably more trouble than it's worth. The CF cards seem to be tied to the IDE interface somehow, as the IDE to CF adapters have no support chips on them at all...it's just the wires directly from the IDE cable to the CF card (with the expception of external power). I am guessing in order to get the CF to work on SCSI would require some kind of custom IC, and probably be very similar to the SCSI to IDE bridge adapters sold by companies like ACARD. The acard adapters are something like $80 new, and $40 used. I've been waiting for quite some time for somebody to make a cheaper one, but it just doesn't seem like it's going to happen. I just went ahead and bought the damn ACARD bridge adapter. It may not be cheap, but in my mind it's worth it

You can find them on ebay by searching for ACARD or AEC-2270U.
 
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