es2a+@andrew.cmu.edu (Eric Stuyvesant) (06/05/91)
I've been considering building some sort of RAM disk for my 4 Mb
1040STE, and was wondering if anyone else out there would be similarly
interested...
Necessary components of said RAM disk:
* use of SIMMs
* support of at least 2 Mb in a minimum construction
* support for different sized SIMMs (256K, 1Meg, 4Meg)
* as cheap as possible
I have considered several different lines of attack, including the following:
* Cartridge port interface, similar to the Alpha Systems RAMdisk. This
has the disadvantage of being slow, and very non-portable to non-ST
systems.
* Serial interface, possibly with a native CPU. This would definitely
be slow, even at 19200, but would be supremely portable to non-ST
systems.
* SCSI interface, possibly with a native CPU. I imagine that this
would be rather expensive to build, due to the cost of SCSI chipsets and
an ACSI->SCSI converter board. It would, however, be useful on non-ST
systems. Throughput would probably be not bad.
* ACSI interface, possibly with a native CPU. This would probably be
easier and cheaper to build than the SCSI version, but would be much
less useful on non-STs.
* CPU replacement board. Basically, replace the CPU with a CPU+memory
daughterboard. Fast, but again, not useful on non-STs.
I'd like to look at these possibilities in more detail, and try to
get at the relative costs and strengths of each of these, then build
something. Is there anyone else out there who would be interested in
working on this? I'm sort of surprised that there are no commercial
SCSI RAMdisks on the market. Or am I missing them? Any comments are
welcome, as right now I don't have the hardware knowledge to build one
of these or the software knowledge to write the drivers.
-Eric Stuyvesant
es2a+@andrew.cmu.edu || es2a%andrew@CMCCVB || JNET%"es2a%andrew@CMCCVB"
al782@cleveland.Freenet.Edu || {uunet,harvard}!andrew.cmu.edu!es2a
"To hate is to study, to study is to understand, to understand is to
appreciate, to appreciate is to love." -John A. Wheeler
Go MEMS!mbaker@ucs.adelaide.edu.au (Matthew Baker) (06/05/91)
(I'm posting rather than mailing because I think this has potential to be an ST topic) From article <QcGzpBG00UgI9Yw5kd@andrew.cmu.edu>, by es2a+@andrew.cmu.edu (Eric Stuyvesant): > > I've been considering building some sort of RAM disk for my 4 Mb > 1040STE, and was wondering if anyone else out there would be similarly > interested... If it works, I might build one (huge :) > Necessary components of said RAM disk: > > * use of SIMMs - SIPs would result in a slightly cheaper device. Use machine pin socket strip instead of $IMM $ocket$ > * support of at least 2 Mb in a minimum construction > * support for different sized SIMMs (256K, 1Meg, 4Meg) > * as cheap as possible -A major hassle with _anything_ using DRAMS is the refresh timing. The TI 746301 is the only DRAM controller I have had much experience with, and that was extremely frustrating. Hence I use SRAMS in all my projects. :) > > * Cartridge port interface, similar to the Alpha Systems RAMdisk. This > has the disadvantage of being slow, and very non-portable to non-ST > systems. Not necessarily slow, but inconvenient. Means a large box stuck to the side of the machine. > > * Serial interface, possibly with a native CPU. This would definitely > be slow, even at 19200, but would be supremely portable to non-ST > systems. Considered building a similar system using an 8086/1772 to use my old ss floppy drive - problems were with the speed as you suggest. Lousy thruput. > * SCSI interface, possibly with a native CPU. I imagine that this > would be rather expensive to build, due to the cost of SCSI chipsets and > an ACSI->SCSI converter board. It would, however, be useful on non-ST > systems. Throughput would probably be not bad. Native CPU more or less essential, (68000 series (eg 010, 070) weould be good) The NCR 5380 - SCSI chip, is not very expensive. Easy to talk to as well. > > * ACSI interface, possibly with a native CPU. This would probably be > easier and cheaper to build than the SCSI version, but would be much > less useful on non-STs. True, less useful. Easier to talk, can do it all without an ACSI chip really (my developmental network adapter uses ACSI for speed - MIDI is way too slow.) > > * CPU replacement board. Basically, replace the CPU with a CPU+memory > daughterboard. Fast, but again, not useful on non-STs. Not worth the effort. Way too complicated, and not much room in an ST. > I'd like to look at these possibilities in more detail, and try to > get at the relative costs and strengths of each of these, then build > something. Is there anyone else out there who would be interested in > working on this? I'm sort of surprised that there are no commercial > SCSI RAMdisks on the market. Or am I missing them? Any comments are > welcome, as right now I don't have the hardware knowledge to build one > of these or the software knowledge to write the drivers. Software is not too difficult... hardware, well, if you're not into hardware, I don't wish to be a downer, but build something simpler first :) It's a _very_ nice idea. Would make a _fantastic_ /tmp device. SCSI sounds good. More comments? > -Eric Stuyvesant Matthew
wallace@ynotme.enet.dec.com (Ray Wallace) (06/06/91)
In article <QcGzpBG00UgI9Yw5kd@andrew.cmu.edu>, es2a+@andrew.cmu.edu (Eric Stuyvesant) writes... > I've been considering building some sort of RAM disk for my 4 Mb >1040STE, and was wondering if anyone else out there would be similarly >interested... Sounds like a fun and usefull project. I think using the DMA port is the way to go. I wonder what it would take to make it be either ACSI or SCSI depending on how you populate the board. Then you could build it to connect right to the DMA port but if you ever wanted to switch to a different computer you could just change a few components and voila. >welcome, as right now I don't have the hardware knowledge to build one >of these or the software knowledge to write the drivers. Hummm... You don't have any software/hardware design experience? Or just not in these areas? If it's the former then I agree with Mathew that you may want to start with a few (a bunch) of simpler projects. --- Ray Wallace (INTERNET,UUCP) wallace@oldtmr.enet.dec.com (UUCP) ...!decwrl!oldtmr.enet!wallace (INTERNET) wallace%oldtmr.enet@decwrl.dec.com ---
jmack@b11.ingr.com (Cery McCormick) (06/07/91)
Eric, I've built a cartridge port RAM disk. It's about par with a fast hard drive when it comes to speed. You are welcome to my schematics if you want them. I have software too. As far as a SCSI ram drive, I have seen an 80MB drive. I can't remember the manufacturer, but I remember that it was very expensive, as in more than $2K. If you decide to go the RS-232 route, I'd be interested in what you have. Cary
es2a+@andrew.cmu.edu (Eric Stuyvesant) (06/07/91)
Well, the reason I wanted to go with SIMMs was that the 256K ones
are getting to be next to (if not) free, and the 1 Meg ones are going to
get to be that way as 4 Meg SIMMs fall even more in price. Yes, SIPPs
would be a *lot* cheaper to mount than SIMMs, but I doubt they are as
easy to find/cheap as used SIMMs. Besides, I *already* have 4 Mb. worth
of 256K SIMMs just waiting to find a home...
This sounds to me like a project eminently worth doing, if I can get
some good books to help my knowledge of digital electronics.
-Eric Stuyvesant
es2a+@andrew.cmu.edu || es2a%andrew@CMCCVB || JNET%"es2a%andrew@CMCCVB"
al782@cleveland.Freenet.Edu || {uunet,harvard}!andrew.cmu.edu!es2a
"To hate is to study, to study is to understand, to understand is to
appreciate, to appreciate is to love." -John A. Wheeler
Go MEMS!avgroeni@cs.ruu.nl (Annius Groenink) (06/07/91)
In <3563@sirius.ucs.adelaide.edu.au> mbaker@ucs.adelaide.edu.au (Matthew Baker) writes: >> Necessary components of said RAM disk: >> >> * use of SIMMs >- SIPs would result in a slightly cheaper device. Use machine pin socket strip >instead of $IMM $ocket$ >> * support of at least 2 Mb in a minimum construction >> * support for different sized SIMMs (256K, 1Meg, 4Meg) I don't know how they've done it, but ATARI has a 26Meg extension for the TT. If that one's a (relatively :) cheap solution, it would be worth using the $IMM$. -- ________________________________________________________ Annius Groenink|undergraduate student Laan van Borgele 24|maths/computer science at the 7415 DJ Deventer|University of Utrecht, Holland.
t68@nikhefh.nikhef.nl (Jos Vermaseren) (06/07/91)
When I was visiting the US in februari I saw an advertisement in some computer journal (maybe the computer buyer) in which a box was offered that acted to the outside as a SCSI device, but the drive was some cards with standard SIMMs. One could plug in a few hundred megabytes when working with 16 Mbytes SIMs. It wasn't very cheap though. The question I have with respect to the Atari is whether it would be needed to write an entirely different driver, because I remember seeing delayloops in one of the older versions of AHDI. Maybe I am mistaken here. For those interested to look up the add: I only looked in one of these telephonebook like buyers guides of feb and the MacUser of feb and march. Maybe other people have seen these adds. Jos Vermaseren
hyc@hanauma.jpl.nasa.gov (Howard Chu) (06/14/91)
In article <676362150.57@egsgate.FidoNet.Org> Matthew.Baker@f98.n250.z1.FidoNet.Org (Matthew Baker) writes: >From article <QcGzpBG00UgI9Yw5kd@andrew.cmu.edu>, by es2a+@andrew.cmu.edu >(Eric Stuyvesant): >> I've been considering building some sort of RAM disk for my 4 Mb >> 1040STE, and was wondering if anyone else out there would be similarly >> interested... >If it works, I might build one (huge :) Well, since I already have a 4MB cartridge port drive from Alpha Systems, yeah, it has to be much larger to be interesting... >> Necessary components of said RAM disk: >> * use of SIMMs >- SIPs would result in a slightly cheaper device. Use machine pin socket >strip >instead of $IMM $ocket$ >> * support of at least 2 Mb in a minimum construction >> * support for different sized SIMMs (256K, 1Meg, 4Meg) >> * as cheap as possible Reasonable... >-A major hassle with _anything_ using DRAMS is the refresh timing. The >TI 746301 is the only DRAM controller I have had much experience with, and >that was extremely frustrating. Hence I use SRAMS in all my projects. :) Sounds nice, but that increases the base cost quite a bit, eh? >> * Cartridge port interface, similar to the Alpha Systems RAMdisk. This >> has the disadvantage of being slow, and very non-portable to non-ST >> systems. >Not necessarily slow, but inconvenient. Means a large box stuck to the side >of >the machine. Yeah, that has certain drawbacks, particularly when working with limited physical desktop space... But now I've got it all hidden inside a tower case, standing next to the desk... >> * Serial interface, possibly with a native CPU. This would definitely >> be slow, even at 19200, but would be supremely portable to non-ST >> systems. Why bother building a solid-state disk only to slow it down behind a silly *serial* interface? Remember 8-bit Ataris? 5-1/4" floppy drives using SIO at a blazing 19200bps?? If you want to drop to that speed, just get some Old Old Old hard drives, you don't need to waste bucks on DRAMs... You could consider the parallel port; it's bidirectional, and most new PC clones also have bidirectional ports now. (If portability is a big issue...) Not sure what the top speed is for that though, I think it's only around 1000cps, which is only slightly faster than a 9600bps serial port... >> * SCSI interface, possibly with a native CPU. I imagine that this >> would be rather expensive to build, due to the cost of SCSI chipsets and >> an ACSI->SCSI converter board. It would, however, be useful on non-ST >> systems. Throughput would probably be not bad. >Native CPU more or less essential, (68000 series (eg 010, 070) weould be >good) >The NCR 5380 - SCSI chip, is not very expensive. Easy to talk to as well. Wanna be even *more* clever... Use SRAM, as suggested, mounted on a removable carrier. Battery on-board the cartridge, of course. That would be really slick... -- -- Howard Chu @ Jet Propulsion Laboratory, Pasadena, CA Disclaimer: How would I know, I just got here!
mbaker@ucs.adelaide.edu.au (Matthew Baker) (06/14/91)
> Wanna be even *more* clever... Use SRAM, as suggested, mounted on a removable > carrier. Battery on-board the cartridge, of course. That would be really > slick... > -- > -- Howard Chu @ Jet Propulsion Laboratory, Pasadena, CA > Disclaimer: How would I know, I just got here! Looking in my Radiospares (yes, we have them here too) catalogue, I find catalogue number 657-246 : a 512Kx8 battery backed memory card, physical dimensions 86x54x3.4mm. Turning to my pricelist, I find the one-off price to be A$1161.80 Immediately I look at the smaller components :) The 32Kx8 card is still A$252.76. Somehow I feel I will let someone with some more money than me play with these. Matthew