asm@utcsri.UUCP (Anees Munshi) (03/02/87)
[]
Hi all.
For my thesis I needed to use the ST's
cartridge port for output as well as input. So I designed an interface
which uses 2 latches and one PAL (16L8) which fits on a tiny cart
plugged into the cartridge port and converts the cartridge port from a
128Kbyte read only port to a 64Kbyte read/write port. The writing
process is a two step process (it involves two reads), and allows you
to write 16bit data through the cartridge port.
I have written software to read and write bytes and words
through this port (in assembler) and have been using this adapter for
nearly 6 months without any problems. (If you are interested in the
design mail me and I'll try to send you the relevent parts of the
documentation of my thesis which I am in the process of writing.)
Since I didn't need too much speed on this port, I never really
benchmarked it until I read those postings about the hardware
ram-disk. Just to see if it would be feasible to use this port to
connect to some memory and make a ramdisk, I decided to benchmark it.
The speed I obtained is about 75978 bytes/second for writes and more
than twice as much for reads. Although this is slower than the DMA
port, given that I don't know of any piece of documentation that
describes the DMA port properly, it might be worth putting a RAM-disk
on the cart. port. In fact, it should be pretty easy to put 2K of
battery-backed CMOS ram, some N meg of dynamic ram, and perhaps a
clock-calendar IC. By using a segmentation register, you could access
the DRAM in 48K chunks or so (leaving some addressable space for things you
might think of later).
So, does anyone have a well commented ramdisk program that I
can modify easily to serve as a driver for the external ram disk?
I would prefer a program in C which I can modify quickly and tune
for efficiency later.
-anees
--
Anees Munshi @ University of Toronto Engineering.
ARPA asm%csri.toronto.edu@csnet-relay.arpa
BitNet asm@utcsri.UTORONTO
CSNet asm@csri.toronto.edu
UUCP {allegra,ihnp4,decvax,pyramid}!utzoo!utcsri!asm
Reality is so much better!stone@calgary.UUCP (Glen Stone) (07/24/87)
Okay, time to clear up some concepts of the external ram disk:
-It will operate exactly as if it was a hard disk, except
it will be faster. The advantages should be clear:
o If your system crashes your ram disk is still intact
o no matter what "meg" machine you have, you don't
have to use up valuable "core." This is important
to all us multi-tasking freaks.
o Proper use of the thing dictates that you store
non-volatile files (compilers, editors) and temp
files on it.
o no mechanical wear, ie use it for development work,
extend the life of your floppy or hard drives.
o gives you the ability to do serious development with out
a hard drive (the idea of this thing is it should cost less
than a hard drive)
o there's probably some other advantages.
Yes I'm designing the thing to be as flexible as possible.
The concept of battery back is interesting. It is easy to provide the
logic, but consider this:
o How long should the batteries last, depending
on size of memory and time required you may
want a portable generator.
o Memory chips have an interesting spec, the average
time between a bit hit form the sun or where ever.
I belive you can expect on a 1 meg. chip a bit hit
every seven days.
I strongly reccomend that the use of this ram disk does not get
distorted. The reason I've decided to make is to speed up my
software development cycle....READ TEMPORARY FILES.
I intend also in making a full SCSI ram disk too.
I see no reason that our friends in Europe can't get a hold of
it.
People seemed to like all methods of availability.
(Yes I'll supply just docs for thos who them)
edrury@percival.UUCP (Ed Drury) (07/26/87)
In article <1035@vaxb.calgary.UUCP> stone@calgary.UUCP (Glen Stone) writes: >Yes I'm designing the thing to be as flexible as possible. >The concept of battery back is interesting. It is easy to provide the >logic, but consider this: > > > o How long should the batteries last, depending > on size of memory and time required you may > want a portable generator. The batteries should be able to give you about 8 hours. That would get you through most outages. The product that comes to my mind instantly is Semi disk. It had a BBU that is perfectly wonderful! >I strongly reccomend that the use of this ram disk does not get >distorted. The reason I've decided to make is to speed up my >software development cycle....READ TEMPORARY FILES. I see it has a great way to speed up disk intensive applications like DMS and ah yes BBS programs. With a reasonable Battery backup unit it would be perfect for shuch applications. ..Remember, if some weirdo in a blue suit offers you some DOS, just say no ...!{ucbvax,ihnp4,seismo}!tektronix!reed!percival!edrury
terrell@laidbak.UUCP (Eric R. Terrell) (07/28/87)
Has anyone used "polydisk st" from alpha systems? It is a 512K external ramdisk that fits in the cartridge port. I am very interested in the product, but am reluctant to buy it without a recommendation. Eric Terrell
Sheldon_Hijacker_Chang@cup.portal.com (08/05/87)
Gee Erik, why don't you just get an Memory upgrade??
crash@calgary.UUCP (Glen ) (01/31/88)
Hi, Well the external ram disk project is moving ahead very well. I expect chips back from fab at the begining of March. If it works, Then the chip and a pc board will be for sale initially. I haven't got any time for marketing and such until I finally get school finnished! Thus, only people who can work a solder iron will want the Ram Disk. When I do get time, I figure out how to sell them as packaged units. As I keep promising... I'll put up some info about the chip, kit etc. soon (that is, soon as I type it !) If your interested in one of the chip and board versions send me mail. If you already have then I've still got it. i don't know how many working chips I'll have, but I'm told at least 20. Requests will be handled first come first serve. Glen P.S. I'd be interested in just selling the chips to someone and they could market packaged units or something like that.
crash@calgary.UUCP (Glen ) (02/10/88)
Hi,
This is for all those asking for more info: (in rough form)
2.1 Definition of Project
The project consists of the construction of an external
ram disk that interfaces to the ATARI ST computer family.
This consists of a custom chip that implements directly the
communication with the ATARI ST over the hard disk
interface. It will implement the hardware handshaking of the
hardisk interface and will interpet the low level commands
required for data transfer. The chip will also directly
control and access the ram disk memory. Two types of memory
chips can be controlled, 256K chips and 1meg chips. The maximum
memory for the ram disk is 2meg or 8meg. The two types of
memory cannot be intermixed.
The project must also allow hard disks that normally use
this interface to continue doing so. This invloves buffering
of the hardware interface with TTL drivers. Other inclusions
that should be consisdered are:
o software driver resident in the ATARI ST
o memory test (hardware or via the driver)
o battery backup of memory <- not viable
o the ram disk has it's own power source
A pcb is being made that supports the 256K chips. Initial
versions of the ram disk will be offered in kit form (chip
and pcb).
No pricing yet, sorry.hase@netmbx.UUCP (Hartmut Semken) (02/17/88)
In article <1341@vaxb.calgary.UUCP> crash@calgary.UUCP (Glen ) writes: >A pcb is being made that supports the 256K chips. Initial >versions of the ram disk will be offered in kit form (chip >and pcb). > >No pricing yet, sorry. Hmm, sounds fine but... No pricing? Why? I've got a memory upgrade from a German company called rhotron. They made a computer called mc68000 in the early days of 68k with 8 slots for expansion. When Atari came up with the ST, they made a backplane with the slots and a little logic to interface it to the ST. I am using this bus system and a 2 Meg DRam-Board for 1 1/2 year now; I'm really happy having 1 Meg of RAM, 2 Meg RAMDisk (reset resident and booteble) and still 7 slots left. Pricing yet: BUS about 400 Deutsche Mark (1$ = 1.7 DM) 2 Meg about 800 Deutsche Mark. hase -- Hartmut Semken, Berlin (West) (*east of West-Germany :-) hase@netmbx.UUCP answer: 42 question: under development. Stay tuned.
crash@calgary.UUCP (Glen ) (02/19/88)
In article <1375@netmbx.UUCP>, hase@netmbx.UUCP (Hartmut Semken) writes: > > Hmm, sounds fine but... > No pricing? Why? > The reason is simple, the solution complex. I have to figure out how many ram disk chips would sell. I have to be accurate as the number is important to re-coupe developement costs of the custom chip. About the hard disk accerlerator. I believe an external ram disk is still the way to go. The accelerator will only help a tight grouping of disk accessing like compiles and still not as fast as a ram disk. But for just loading a program, ie emacs, the accelerator will be of no help. It can't be much help on temporary files (can it?). Any comments??? The pricing structure will go like this. Estimate total sales of the chip. Divide by development costs. Sell chips at some price, thus the first twenty chips will be the same price as all the rest. My problem is I don't know anything about marketing! Glen PS. still some confusion...the ram disk does not increase core. If you have a 520 and a program needs 1 meg to run the ram disk will not help (unless you have virtual memory op. system). for those who then say "Well, what good is it?"- Never mind.
stone@amc-vlsi.UUCP (Glen Stone) (04/19/88)
Hi: Well the external ram disk chip is back from fab and is talking to the atari! All I have to do is write a driver now. I ran it with 2 meg (64 256K chips) and average current is only 1/2 amp. Peak is way up there... 3~4 amps. But no cooling fan is required, yippee. I still have to due extensive testing, including reliability testing. Sure wish ram prices would come down. Glen Stone P.S. Sorry to the people who send me mail, wanting a reply and not getting it. I try, but can't seem to get through on some paths.
stone@amc-vlsi.UUCP (Glen Stone) (04/22/88)
Hi, Well, I'm peeing myself constantly. The external ram disk will run from any hard disk driver as I had hoped (expected). Thus if you have a hard disk then the software that it comes with (ie. Atari, Supra) will run it. You can even boot from it. Hell, you can even "park the head." I'll still supply a driver though, as people with just floppies will need it. Currently I'm running a 2 meg ram disk using 256K chips and a SH204 hard disk. Things are working great. I've loaded my bin, lib, and include to the ram disk (as well as temp). Running from a shell my response time has improved. I compiled a program consisting of 4 c files and 3 s files from hard disk and from ram disk, the times are: Ram Disk: 177 sec Hard Disk: 241 sec I'm using Alcy(holic) 4.14 and the Bammi cc program. Oh yes, using MadMac and Aln. For those interested, you maybe should phone. Mail doesn't always make it here. Glen Stone (403) 277-9171 night (403) 289-2043 day