An AVL Eagle II Computer shows its elegant styling.
Click on the picture to enlarge it.

CP/M models

The AVL Eagle I and II had audio-visual connectors on the back.  As a separate company, Eagle sold the Eagle I, II, III, IV, and V computer models, and external SASI hard-disk boxes called the File 10 and the File 40.

Contents

• Basic design
• Storage options
• Upgrades and modifications
  • Hardware changes
  • Software changes
• Software
  • CP/M operating system
    • Disk formats
    • Drive letters
    • Utilities
  • Eagle utilities
  • Spellbinder
  • Accounting Plus or Ultracalc
• Manuals
• IIE or not IIE
• Old Eagles today

Basic design

Front and rear views of an Eagle II computer.
Click on either picture to enlarge it.

All CP/M Eagles had the same basic design, different only in their storage devices.  An attractive off-white case held the entire computer.  The top section held a green monochrome monitor on the left, and one or two full-height storage devices, stacked one above the other, on the right.  An anti-glare screen was held in place against the front of the monitor, and the front of the top section shut, by a black plastic bezel.  This bezel snapped into place.  The top rear of this section had a screened air vent, a fan was located right behind the drive enclosure, and a silver label behind the monitor gave the company logo and address, the model number, serial number, voltage, frequency, and current.

Ports of an Eagle computer.

Rear of an AVL Eagle.  Note the A-V ports between the reset button and the serial ports.

The bottom section projected forward and had the keyboard in its top, and the system logo.  Inside this "clamshell" was the main circuit board, connected to the monitor, drives, keyboard and ports by cables.  Underneath the main board and connected to it by cables was a Xebec hard-disk controller board.  On the back of the clamshell was the reset button, two RS-232 serial ports labeled "Serial A" and "Serial B", a Centronics parallel port labeled "Parallel A", a SASI port labeled "Parallel B", the brightness knob for the monitor, and the on/off switch.

The keyboard was well designed.  The keys were black with white lettering.  Besides a full typewriter keyboard, there was a complete ten-key number pad on the right, by no means common at that time.  Labels on the front of the number keys of the typewriter keyboard, and all the keys of the number pad, denoted what function those keys performed in the command mode of the bundled Spellbinder software.

Close-up of the Eagle keyboard.
Click on the picture to enlarge it.

The CPU of the whole line was a 4-MHz Zilog Z-80A, the standard microprocessor of the day.  Memory was 64K, which was all the RAM that the standard CP/M 2.2 operating system could address with an 8-bit chip.

Storage options

An Eagle IV or V had its main board raised off the bottom of the clamshell with stand-offs, and the SASI board and Xebec controller boards were underneath the main board.  The second power supply, needed for the heavy power draw of the hard disk starting up, was mounted on the inside of the top of the computer, next to the air vents and above everything else it would otherwise heat up.

Eagle also sold external hard-disk units called the File 10 and File 40.  These were metal Corvus boxes with a fan and power switch on the back.  The only difference was the Eagle label instead of the Corvus label.  Inside a File 10 was the same hard disk as an Eagle IV had, the same Eagle SASI card, and a power supply.  The File 40 had the same 32-Mb hard disk as an Eagle V.

An Eagle III owner could buy a File 40, connect it to the "Parallel B" port on the back of the Eagle with the ribbon cable that came with it, turn on the File 40, and turn on the Eagle.  If a File 10 or File 40 was attached and turned on when an Eagle I, II, or III was turned on, the computer booted from the hard disk in the external box, even if a bootable floppy disk was in a floppy-disk drive.

An Eagle III with a File 10 attached had the same hard-disk storage as an Eagle IV, but two floppy-disk drives instead of one.  Similarly, with a File 40 attached, it was functionally the same as an Eagle V with an extra floppy-disk drive.

All drives were full-height, 5¼-inch form factor.  This means floppy-disk drives and hard disks both.

Upgrades and modifications

Hardware changes

An Eagle I computer had only one drive.
Click on the picture to enlarge it.

Eagles were easy to open and easy to upgrade.  The only difference between an Eagle I and an Eagle II, for instance, was the number of floppy-disk drives.  Remove the plastic cover on the front of the lower half of the drive enclosure, attach a second single-sided 96-tpi drive to the drive and power cables, make sure that its jumper is set correctly, and the I is now a II.  Add two double-sided quad-density drives to a I or a II, and it's now identical to a III just as it came from the store.  (An Eagle with only one double-sided drive was sometimes called, in jest, a "2 and a half" or a "III minus".)  By adding the right drives, and a hard disk, SASI card, and extra power supply, a I could be upgraded to a II, III, IV, or V; a III could become a IV or V; a IV could become a V.

When half-height floppy-disk drives and hard disks became available, Eagle drives that had worn out could be replaced with ones that took up less space, drew less power, and weighed less.  The Eagle BIOSes supported up to two double-sided floppy-disk drives and up to four 8-Mb hard-disk partitions.  Systems could be built with two half-height floppies and a 10-, 20-, or 32-Mb hard disk.  (A system with two floppies and a 10-Mb hard disk was jokingly called a "IV plus", while one with a 20-Mb hard disk was called a "4 and a half" however many floppies it had.)

Just to see whether it would work, Jerry Davis and I mounted two half-height 10-Mb hard disks in an Eagle, each attached to its own SASI card, both cards connected to the same Xebec controller.  This "IV by two" worked perfectly, but it was a big waste of resources; the Eagle SASI card was the rarest and hardest-to-find part of the computer, since only Eagle made them and not all Eagles had them to begin with.

Software changes

Computer hobbyists continued to improve CP/M in various ways even after Digital Research was out of business.  A computer was said to be running The Z-System, rather than CP/M, if the CP/M CCP had been replaced by ZCPR or a similar command processor, the BDOS by ZRDOS or Z3DOS, or both.  This could be done manually, if the source code for the BIOS were available, or automatically with various packages such as Joe Wright's NZ-COM.

One long-term concern with Eagles was how loud the hard disks were, and how they seemed to hunt over and over whenever reading or writing data.  Bob Vinisky bought NZ-COM from Alpha Systems Corporation, and was amazed and gratified that the hard disk of his Eagle IV now ran quickly and quietly.  This observation was confirmed whenever an Eagle had The Z-System installed.

Software

The software for the CP/M Eagles came on 5.25" floppy disks:

If you bought an Eagle IV, Eagle V, File 10, or File 40, all the software was already installed.

CP/M operating system

BIOS: CP/M consisted of three parts, two of which never changed and were copyrighted by Digital Research.  The third part, the BIOS, was the interface between the operating system and the hardware, which was very different between one company's computers and another's, and sometimes between different models from the same company.  The BIOS was written and copyrighted by the manufacturer.  There were three Eagle BIOSes:

• The Eagle II BIOS supported 2 single-sided floppy-disk drives.  It was used by the Eagle I and II.
• The Eagle III BIOS supported 2 double-sided floppy-disk drives.  It was used by the Eagle III.
• The Eagle V BIOS supported 2 double-sided floppy-disk drives and 4 hard-disk partitions.  It was used by the Eagle IV, Eagle V, File 10 and File 40.

Disk formats: The format for floppy disks and hard disks is defined in the BIOS, and every manufacturer of a CP/M computer had its own.  Eagle kept it simple.

There was a single-sided floppy-disk format, and a double-sided one.  Furthermore, they were identical on one side.  The double-sided format filled up the first side just like the single-sided format, then continued on the second side.  This wasn't as efficient as writing first one side of the disk, and then the other, before moving the drive head, but it was done deliberately to make the two formats as alike as possible.  A customer who upgraded from a I or II to a III, IV, or V didn't need to copy his old disks to the format of his new machine.

There was only one hard-disk format.  The format program required a hard disk with the right number of heads, platters, and cylinders.  There were numerous makes and models of 10-, 20-, and 32-Mb hard disks that met that requirement.  The program formatted the hard disk 8 megabytes at a time (CP/M's limit for a logical disk drive) until it had successfully finished four partitions and quit, or suddenly ran out of hard disk.  Thus a 10-Mb hard disk had an 8-Mb partition and a 2-Mb partition; a 20-Mb hard disk had two 8-Mb partitions and one 4-Mb partition; and a 32-Mb hard disk had four 8-Mb partitions.  (The "IV by 2" mentioned above, with two 10-Mb hard disks inside it, had four partitions: 8 Mb, 2 Mb, 8 Mb, and 2 Mb.)

Drive letters: In CP/M, the drive booted from is drive A, whether it's a floppy disk or a hard disk.  In addition, double-sided Eagles addressed single-sided floppies as drive I or J.  Which drive letter applied to which device did not change on a given system, but modifying systems could be confusing:

If an Eagle booted from a File 10, File 40, or "File 20" (a File 10 or File 40 box with a 20-Mb hard disk inside), the drive-letter assignments of the hard-disk BIOS prevailed.  The external hard disk's partitions would be A and B for a File 10; A, B, and C for a "File 20", and A, B, C, and D for a File 40.  The top floppy would be E and I and the bottom one F and J, unless they were single-sided floppies, which could only be I and J.

Since the hard-disk BIOS only addressed four hard-disk partitions, an Eagle IV with a File 10 attached would address the two partitions of the File 10 as A and B, and the two in the Eagle as C and D.  With a "File 20" attached, the external partitions would be A, B, and C, the 8-Mb internal partition would be D, and the other internal partition couldn't be used at all.  Similarly, with a File 40 attached, no partitions of a hard disk in the Eagle could be read from or written to, because all available hard-disk partitions were assigned to the File 40.

Utilities: All the standard CP/M utilities were included: PIP to copy files, etc.  DRI's sophisticated compiled BASIC programming language, CBASIC, was also included.

Eagle utilities

Every CP/M computer manufacturer supplied additional software utilities, in much the same way that Linux distributions add their own installer, etc. to the standard kernel and libraries.  On Eagles, they were:

• HELLO: In CP/M there is a certain address which holds 8 bytes, normally blank.  If this location is patched with a word like "HELLO", then the operating system on booting will look for a HELLO.COM or HELLO.BAT, and if it finds one, will run it.  All the Eagle software disks except the system disk, and all Eagle hard-disk systems, ran a menu program on booting.  The bundled software appears on this menu, so the user doesn't have to type the names of the programs at all, just type a number from the menu.  A utilities sub-menu even includes things like "Copy from the top floppy to the bottom floppy" and "Turn off the computer safely" so that the customer doesn't have to learn PIP or remember to park the hard disk.  More experienced users could exit from the menu program, rename HELLO.COM to something else to prevent it from being started, or even patch CP/M to remove the "HELLO" entry.
• FORMAT and HDFORMAT: These are the floppy-disk and hard-disk formatting programs, described above under the CP/M BIOS.
• BACKUP: This program let the user specify what files he wanted to back up from a hard disk and save on floppies; and he could save the specification list in a file.  Note that with a floppy-disk format of about 3/4 of a megabyte, it only took 12 or 13 floppies to back up an Eagle IV, even if the hard disk was completely full.  When the user ran BACKUP, it asked for a name for the set and a comment to identify it; this information was stored on each floppy disk of the set.  It didn't matter what size the files were because of BACKUP's intelligent design.  If it ran out of disk space in the middle of a file, BACKUP asked its owner to insert the next disk, and continued backing up the file onto the next disk.
• RESTORE: Like BACKUP, RESTORE allowed an Eagle user to specify the file(s) to work on, in an input file.  If a file to be restored had been divided across two or more disks, RESTORE would ask for disks as it needed them, and tell its user if he put in the wrong disk.  Of course, if a file weren't divided, and the user knew what disk it was on, he could also restore it with PIP or some regular copy program.
• PWRDWN: When Eagles were made, hard-disk read/write heads would come down on the platter when turned off, and data could be lost unless they were first moved to a special location.  The PWRDWN command parked the head so an Eagle with a hard disk could be turned off safely.

Spellbinder word processor

Spellbinder, from Lexisoft, was a powerful word processor which was highly configurable and even had a built-in programming language for automating tasks.  Eagle computers came with a version of Spellbinder already configured, with many functions already assigned to keys (the keys had labels on their fronts to show their Spellbinder functions).  The only configuration needed, then, was to set it up for a given printer; and for most printers, that just meant choosing the printer off a list.

The combination of Spellbinder software, the Eagle keyboard, and the large storage capacity of Eagle floppies made a word-processing machine so powerful for its day that many Eagle owners never realized how much more their computers were capable of.

Accounting Plus or Ultracalc

Eagles were marketed as business machines, so financial software had to be part of the package.  Originally this was Accounting Plus, a professional bookkeeping system so large that it took six Eagle double-sided 784K floppy disks to hold it all, and required constant disk swapping on an Eagle without a hard disk.

Constant protests, questions, and requests for customer support led Eagle to stop bundling Accounting Plus with its computers.  Most users simply didn't need all that.  Ultracalc, a spreadsheet program from Sorcim, was substituted on later machines.

Manuals

An AVL Eagle and its documentation.
Click on the picture to enlarge it.

Eagles early enough to come with Accounting Plus, whether made by AVL or Eagle, had two black binders of documentation.  One, labeled "Accounting", was the Accounting Plus manual.  The binder labeled "Users Guide" contained everything else.  The picture above also shows an AVL binder for ProCall.  ProCall was a program for dialing up bulletin boards or exchanging files with other computers remotely.  Either some salesman went the extra mile to prepare a ProCall binder just like the standard ones, or this was an option if you bought a modem with your computer.

Eagle documentation and some extras.
Click on the picture to enlarge it.

The spine of the Eagle binder.

Later Eagles had a single white binder with the Eagle logo across the top of the spine and "Eagle Software Manual" down along it.  This contained a manual, written by Eagle, which told how to use the computer, including Spellbinder and Ultracalc, without distinguishing Eagle's software from Lexisoft's or Sorcim's.  Mentors at Eagle Computer User Group meetings would often have to explain, in fact, that there were separate programs on the computer, written by separate companies; between the manual and the menu system, it looked like one big program to the new computer user.

The documentation binder also contained a thin spiral-bound book called "CP/M Primer," which gave a very superficial idea of what an operating system was, why you had to format disks before using them, and so forth.  Eagle owners could also buy the hardware manual from Eagle, that included the schematics of the main board; the regular Spellbinder manual and Spellbinder MPL (Macro Programming Language) manual from Lexisoft; and the manuals for the Digital Research products bundled with their computer, as well as other products that were not.  But none of this was part of the standard Eagle documentation.

IIE or not IIE

A confusing marketing move that Eagle made, at about the same time it introduced its first "16-bit" computers, was to rename its CP/M line.  Before, the logo on the keyboard announced the computer's model: Eagle I, II, III, IV, or V.

Now Eagle renamed the entire line the Eagle IIE series, perhaps in an attempt to confuse buyers with the popular Apple IIe computer (but note IIe for the Apple and IIE for the Eagle).  Now every 8-bit Eagle computer had a keyboard label that looked like this:

Confusion was not total, however.  If the prospective buyer looked at the silver label on the back of the machine, he would find the model described as IIE-1, IIE-2, IIE-3, IIE-4, or IIE-5, corresponding to the I, II, III, IV, and V.

Old Eagles Today

Floppy-disk drive trying to read a floppy

A computer collector or hobbyist who finds an computer in storage since the 1980's should not get his hopes up until he sees whether the computer runs when it's turned on, whether the software is also present, and whether the monitor works.

Make sure the computer is dry before trying to turn it on.  If it's been stored in a damp or even just a cold place, put it in a warm spot and let it dry for a day before plugging it in and turning it on.  Open it up with a screwdriver and (without touching anything) look for obvious signs of damage, such as rat toothmarks on the main board or a corroded hole, surrounded by yellow crystals, where cat urine has eaten through vital components (I'm not kidding, folks).  Dampness and light mold can be wiped away with a dry cloth, but ground yourself first.  A thick layer of dust should be blown away with compressed air, rather than wiped; wear a mask over your nose and mouth while you do this.

Before turning the machine on, open the floppy-disk drives.  If you're lucky, whoever stored the machine put a floppy disk in the drive before closing them, to cushion the drive spindles and keep them from sticking together over time.  The drives should always be open, or have a floppy disk in them, when the machine is running.

Some causes of failure may be expected in any computer built the same way.  If chips are attached to the boards in sockets, rather than soldered on, they may be loose because they expanded from heat whenever the computer was on for a long time, then contracted whenever the computer was turned off.  A computer that was used a great deal, and for a long time, may require a new owner to open it up and gently press the chips down before it will run.  My first Eagle IV developed this problem, and I saw it in other old machines at user-group meetings.

Another problem sometimes found in old Eagles with hard disks is stiction.  Hard disk read/write heads from that era rested on the platter when turned off, and may adhere to where they've been sitting with greater force than the drive motor can exert on starting.  An experienced technician may be able to coax the head free without destroying the hard disk or losing data; I've seen Jerry Davis do this.

This message means that you didn't put a floppy disk in the drive, or you put it in the bottom drive instead of the top, or it doesn't have CP/M on its system tracks.  But hey, at least you can read it!  So your character chip is still working.  Now turn down the brightness on your screen.

The most common problem peculiar to CP/M Eagles, in particular, involves the character generator chip on the main board.  This tends to fail with age, so that a line of text will have the dots of its letters scattered unreadably all over the screen.  By the time this problem became apparent, the chip was no longer made, but they were still readily available in parts warehouses.  Today a collector's only hope is that the previous owner stored spare character-generator chips or spare main boards with the Eagle.

Copyright © 2006-2007 by Green Sky Press.  All rights reserved.  Backgrounds and images are copyright by their respective authors, who retain all rights.

This page has been validated against XHTML Strict and viewed under Konqueror, Firefox, Opera, and Internet Explorer at a screen resolution of 1024 × 768.  If you find any bugs, please contact me at the e-mail address on the home page.