3. More HardwareHere are some more pieces of the hardware jigsaw, that you should have. Remember the get a three button mouse, it makes a huge difference. |
You want an EIDE - ATAPI CDROM, because that's the easiest, cheapest, common and fast.
However you might choose to buy something else, or find yourself with a different type of drive and interface. Whatever type of CDROM you get, you must understand what TYPE it is, and how to configure it.
Different CDROMS have different interface cards and cables.
SCSI CDROM's are driven by a SCSI card. Normally you buy that separately, and need a specific driver for the card, but the CDROM drive should be standard. Some bundled interface cards are brain-damaged, and only drive a CDROM, or a particular device. Most good ones are very portable. External SCSI drives may have problems with cables. i.e. external SCSI cables can only have 2 devices and need proper termination. Theoretically you can have more, but in practice ...
Internal SCSI CDROM's are good, just slightly more expensive. You configure them as /dev/sdc and symb link that to /dev/cdrom, unless it has several platters, such as an auto-changer with each on a separate LUN address. Proper jukeboxes don't do 'virtual' emulation of all the disk being online, but those that do, work with no code!
CDROM's first became popular thanks to sound card's having a special CDROM interface on them. What interface you have depends on what model you have. Some cards have a switchable "triple" interface (either sound cards or non-sound cards).
That interface circuitry is totally independent of the sound card, simply in the same package. Music from the CD into the sound channel went through an analogue wire and socket, like the microphone, only a different plug, and inside the case not outside.
The CDROM manufacturers created a half a dozen different interface specifications, and the sound card's would support one or three of them. The manufacturers also produced a really cheap interface card, for people without sound cards.
On my old machine, I have an old dual speed CR-562 on it's own interface card. On raven I have an EIDE quad speed.
The CR-562 uses a Panasonic interface, that appeared
on original sound cards (hence the misnomer
sbpcd). Also known as a Matsushita interface.
That means that I configure my old CDROM as /dev/sbpcd at IO=0x320 (a really strange address for a Panasonic/Matsushita, but that is the card I have). It needs the sbpcd driver compiled into the kernel (or available as a module). EIDE CDROMS do not use sbpcd.
External SCSI CDROM's may require high quality cables and limit the number of drives that can be cascaded (2). This is a generic problem with external SCSI and is often helped by good termination (active).
EIGHT-speed and TWENTY-FOUR-speed IDE CDROMS are now available for a few pounds more. After that check seek/access times and reliability.
SEVEN-DISK auto-changer, is an interesting idea (especially audio), but there would be a 3 second delay when switching between tasks, accessing different disks. The cost including the SCSI controller would buy a few quad-speed always-online CD-ROMS (in a tower case).
TRIPLE-DISK-IDE auto-changers. I saw an advert for these, but I don't know how well they are supported. If you have one of these, check for the eject package, which claims that it can switch CD's, after which it then looks like an ordinary EIDE CDROM. This is a recent release of eject, so don't stop until you find it.
Don't forget to enable IDE-CDROM (or your device type) in the kernel when you compile it. You know it's there, because when the kernel boots, it lists all drives found, and says "CDROM" against one of them. If the messages ran by too fast, run dmesg.
CDR (R=recorder) are coming down in price, mostly because of volume sales and new models forcing down the prices of old models.
A CDR isn't part of the basic Raven spec, but expect to buy one next year. You can get a Ricoh-1640C with an internal 2 MB buffer for £250. Then you will need cdrecord to make it work.
You could also look at one of the packet writable CDROM's, these allow you to write individual files rather than multi-sessions (each session has a substantial overhead), browse the site to see which are supprted.
There are also rewritable CDROMS, which use more expensive (20) media, but can erase and rewrite many times. Even more expensive and to what end?
The next problem is that 645 MB is just not enough! When we have 10 GIG media, things will change dramatically, but that's a couple of years until it gets cheap, and common.
In the mean time, get a 3 GIG disk, create the 10 MB boot partition (see Issue-2-SysBuild), and create lots of 670 MB partitions. You can copy whole CD's onto a free partition, or create your own using mkisofs. Then mount it to see that it is OK. I have a line in /etc/fstab:
/dev/hdc4 /hdc4 iso9660 defaults 2 0Except the
defaults word reads:
defaults,noauto,ro,user,exec,suid
cd-writers have to get the data on-time, first-time. If the program driving the CDROM has to get lots of files from different disks, the throughput may not be sufficient to feed the laser. That's why it's better to build an image (which is sequential blocks on one partition), or possibly a file-image (which is mostly sequential blocks, but might be fragmented).
Multi-session is a good idea. It allows you to write 5 lots of 100 MB, instead of having to collect it all in one image, and it is supported by most CDROM readers.
Some people have reported limited lifespans of the drive and laser, this may be specific to their brands (and basic mechanisms). Look for other docs on the Internet with this info.
Linux will drive a POSTSCRIPT printer or any "common" printer. HP, Epson, 24-bit dot matrix, color-ink-jet, PCL, etc. You can get a second hand 9-pin for £20, but they are slow and noisy.
I don't know anything about laser memory requirements, for complex pages. Especially since ghostscript will be converting to a pixel image.
GDI requires MS-Windows software to drive it. I don't think Linux does this yet. But some GDI printers have an 'upgrade to normal printer add-in'. and can be driven in PCL from DOS.
Printer cables can be quite long, but beware of total length, with switch-boxes. The printer will go quiet if the total footage is excessive (40 ft). If you are lucky, you can avoid buying an expensive, bulky and messy printer, and use the printer at College, or work.
Don't bother. Get a second disk, and keep YOUR files on floppies. Label the floppies 9601-Jan, and keep backups of them on an ext2 disk. Take TAPE backups of that ext2 disk.
The system is HUGE, but can be deleted and re-loaded from CDROM (as you shall see ...). Reloading the system from scratch is difficult to get right without forgetting SOMETHING, but each time, make a note to improve next time's installation procedure.
Collect all the ftp files you found. Put the ones you have installed on a backup archive. If the machine needs to be rebuilt, you have them.
For site backups use an external CD-writer. This won't backup working PC's, but you prepare a 660+ MB image using mkisofs, and borrow the CD-Writer for an hour (or so). Sites with incremental backups merge departments, each 'posts' 50M to a weekly backup (N-copies takes N-hour's raw cost £7 each :-). How do you dispose of CD's?
Some tape drives are very noisy, and can't be active in the same room as a human being. DAT tapes (quiet) have a high capacity, but cost a lot, and do wear-out after 2 years of daily use.
I have an old Syquest SCSI 80 MB cartridge, which works very well. There are newer 1 Gig drives, and these should work well, (using standard SCSI interfaces). You might be looking at the 1 GB Jazz drivers or similar.
I did have problems with DOS requiring a reboot on every change, but this is NOT a problem with Linux, it accepts the SCSI media change signal, and rereads the fdisk info. I simply do:
umount /syq # remove media insert new media mount /syq
They are more expensive, and slower than fixed disks, but may be more suitable for sending through the post to get CDROM's cut, or more convenient for archives, or moving between machines.
The parallel interfaces, will be much slower than internal SCSI cards, and you should check whether they are supported or not, and the convenience looks very tempting. However it is another box, power cable and interface cable. Portable users would probably swear by them. http://www.torque.net/linux-pp.html
If you don't want to switch disks very often, you might consider an exchangable SCSI or EIDE frame. But do remember, that an exchangeable frame will eventually wear out the electrical connections.
I don't have one, though I have seen one at £20 (second hand). I did have one a long time ago, but I was disappointed by the amount of HISS and general sound quality. I lent it to a friend, who has moved.
System upgrades are easier if you can boot two independent systems (as well as DOS). IE: the old-system and the new-system. If you plan to do that you must reserve the disk now, possibly leaving you with only 2 of 4 disks (+new system, +cdrom). If you plan for that second disk now, but intend to buy it later, it will make more sense when it arrives.
During the migration, you might do a lot of deleting. Be lucky.
If you are lucky, you can share /usr/andrew, eg as /hdc2/andrew (that's the AUIS word processor). With other apps, beware of different library file versions, but see /etc/ld.so.conf. (or is that now in the process of being depracated?).
Put the second IDE on either the first or second EIDE cable and controller.
With both disks on the same cable, one must wait whilst the other uses the IDE cable. You will need a second ide cable (the first one is always included with the controller card), and scrounge a few jumpers. Check that you have enough PSU cables (or a splitter).
DOS used to halve the data path width of a hard drive ON THE SAME CONTROLLER as the IDE CD. Linux does not have this problem. DOS may be fixed with a driver, especially under windows.
Splitting data across two disks can boost performance, for a number of reasons. If you are hardly using the DOS partition, but have a swap space on that disk, every time the system wishes to read or write a swap-page (4K block), it can do so without moving the disk head of the other disk, and conversely. That makes it worth running FIPS on a DOS partition, just to create a 32 MB swap space. You might also try a swap file.
My very old serial logitech mouse accidently got trodden on, and I looked at several on display for £30, and didn't like any of them. Then I resigned myself to the cheapest I could find, without even looking at it. You decide whether you want an Taiwanese mouse in the current political climate.
It is a Genius Easy Mouse, and it is brilliant!
It is a serial mouse, so set /dev/mouse -> /dev/ttyS0, and it is configured as Protocol "MouseSystems" in /etc/XF86Config and in /etc/rc.d.rc.serial it is gpm -t msc.
Mine goes crazy if I configure ClearDTR into /etc/XF86Config, you might need to do that to switch the emulation mode out of Microsoft 2-button mode (there is also a 3-button MS mode). Check your configurations, and try pressing the middle button at power-up boot-time, or when the driver starts.
Don't come home without them!
A null modem cable, allows you two PC's together using the serial port instead of ethernet cards.
It also allows you to connect a VT100 dumb terminal to your Linux box, or let your Linux machine act as a terminal on another machine.
If you buy one or build one, make sure that it matches the following internal wiring diagram. Most do.
Same Null Modem Cable
================================================
SG [7] <----------------------> [7] SG
TD [2] -->-------\/-------<-- [2] TD
RD [3] <----------/\----------> [3] RD
RTS [4] -->-------\/-------<-- [4] RTS
CTS [5] <----------/\----------> [5] CTS
DTR [20] -->-------\/-------<-- [20] DTR
DSR [6] <-----+----/\-----+----> [6] DSR
DCD [8] <-----+ +----> [8] DCD
See the ETHERNET HOWTO for more information about cards. An ISA NE2000 clone, is fast enough to run the wire at full speed, but it probably has a high 'cost' on CPU overhead, hence is 'slower'.
I used jumpered IO_ADDR + IRQ, so that I don't have to run a DOS utility to program the card.
This is rumoured to make all parallel and serial connected devices obsolete. All USB devices will be easier to connect and disconnect, and quite fast enough for most needs.
You do not absolutely need it just yet, but it will be very nice when it it commonplace.
Shops often put out adverts of complete machines at low low prices. These are not fakes, but checking the specification, you may notice only 8Mb RAM, 14" monitor or whatever. Take the specification home and price it on an item-by-item basis. Then go back to the shop with a proposal for an upgraded machine, they'll probably snatch it out of your hand. Remember that their prices depend on sustained turnover, and your thousand will enable them to get newer stock.