Eagle Computer
Eagle Computer, Inc., was an early American computer company based in Los Gatos, California. Spun off from Audio-Visual Laboratories, it first sold a line of popular CP/M computers which were highly praised in the computer magazines of the day. After the IBM PC was launched, Eagle produced the Eagle 1600 series, which ran MS-DOS but were not true clones. When it became evident that the buying public wanted actual clones of the IBM PC, even if a non-clone had better features, Eagle responded with a line of clones, including a portable. The Eagle PCs were always rated highly in computer magazines.
CP/M models
Multi-image 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 SCSI/SASI hard-disk boxes called the File 10 and the File 40.The first Eagle computers were produced by Audio Visual Labs, a company founded by Gary Kappenman in New Jersey in the early 1970s to produce proprietary large-format multi-image equipment. Kappenman introduced the world's first microprocessor-controlled multi-image programming computers, the ShowPro III and V, which were dedicated controllers. In 1980, AVL introduced the first non-dedicated controller, the Eagle. This first Eagle computer used a 16 kHz processor and had a 5-inch disk drive for online storage.
The Eagle ran PROCALL software for writing cues to control up to 30 Ektagraphic projectors, five 16 mm film projectors and 20 auxiliary control points. Digital control data was sourced via an RCA or XLR-type audio connector at the rear of the unit. AVL's proprietary "ClockTrak" was sourced from the control channel of a multitrack analog audio tape deck. The timed list of events in the Eagle was synchronized to the ClockTrak. Later versions of PROCALL included the option of using SMPTE timecode.
Most programmers abandoned ClockTrak for SMPTE, as more multi-image programs began to incorporate video.
Two separate digital data streams were output from the Eagle via RCA or XLR-type audio connectors. These two telemetry streams, called "PosiTrak", each controlled up to five external slide projector control devices manufactured by AVL, known as "Doves". The Dove units received biphase data from the Eagle via audio cables and interpreted the Eagle's data streams to control as many as three and two dry-closure contacts per Dove unit. So then, on its own, the AVL Eagle can drive a multi-image slideshow of up to 30 projectors. AVL also made the Raven, a device similar to the Dove, for comprehensive control of a single 16 mm film projector and numerous other external control devices for lighting, sound, video projectors, and sources, etc.
When properly set up and powered, AVL Eagles and associated products were extremely reliable. During the 1970s through the early 1990s, when its competitors' products were not as reliable nor readily available, AVL became the industry standard for multi-image control equipment. However, the development of large-screen electronic media and HDTV ushered out the era of film-based multi-image productions.
Basic design
All CP/M Eagles had the same basic design, except for the storage devices. The exception was a portable model, in which the keyboard formed a removable lid that could be snapped to the main unit for traveling. An attractive off-white case held the entire computer. The top section had a green monochrome monitor on the left and one or two full-height storage devices stacked 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 was shut by a black plastic bezel. This bezel snapped into place. The back of this section held a fan behind the drive enclosure and a silver label behind the monitor with the company logo, address, model number, serial number, voltage, frequency, and current.The bottom section projected forward and had the keyboard and the system logo on its top. Inside this "clamshell" was the main circuit board, connected to the monitor, drives, keyboard, and ports by cables. A Xebec hard-disk controller card was underneath the main board and connected to it by cables. 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, uncommon 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.
The CPU of the whole line was a 4 MHz Zilog Z80A, 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
| Model | 5.25" Floppy-disk drives | Hard disk | Additional | Price in 1982 |
| I | 1 SSQD 382K | - | - | $1000 |
| II | 2 SSQD 382K | - | - | $1200 |
| III | 2 DSQD 784K | - | - | $1600 |
| IV | 1 DSQD 784K | 10 MB | SASI board, second power supply | $2600 |
| V | 1 DSQD 784K | 32 MB | SASI board, second power supply | $3000 |
Also available were 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. 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.
To upgrade an Eagle III, for instance, the user 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.
Upgrades and modifications
Hardware changes
The original AVL Eagle was an S-100 8080 computer with separate boards for the AVL multi-image interface, the Intel 8080 CPU, floppy drive interface and 16Kb memory cards of which the standard machines only had one. Extra 16Kb memory boards were available if a user could afford one. The boot floppy did not offer to run anything other than Procall unless a user paid for one to run the Electric Pencil word processor.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. 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 and drew less power. The Eagle BIOS 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.
Just to see whether it would work, Eagle Computer Users Group members 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 waste of resources; the Eagle SASI card was the rarest and hardest-to-find part in 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 no longer in 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 had been replaced 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.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. NZ-COM from Alpha Systems Corporation allowed the hard disk of the Eagle IV to run more 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:| Disk label | Contents | On booting, displays |
| System | CP/M, Eagle utilities, CBASIC | A:> prompt |
| Spellbinder | wordprocessor | Menu |
| Ultracalc | spreadsheet | Menu |
For customers who bought an Eagle IV, Eagle V, File 10, or File 40, all of the software was already installed.
CP/M operating system
BIOS: CP/M consisted of three parts, two of which were machine independent and were copyrighted by Digital Research. The third part, the BIOS, was the interface between the operating system and the hardware, and varied between the systems of different computer manufacturers, and sometimes between different models from the same company. The BIOS was written by the manufacturer and copyrighted by that company. 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 and V.
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 whole first side just like the single-sided format, then continued on the second side. This was not as efficient as first writing one track to one side of the disk, and then one track to the other, before moving the drive head to the next track, 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 did not 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 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.
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:
| Model | Floppy-disk drives | Hard-disk partitions |
| I | Top: A | - |
| II | Top: A Bottom: B | - |
| III | Top: A, I Bottom: B, J | - |
| IV | Top: E, I Bottom: F, J | A, B |
| V | Top: E, I Bottom: F, J | A, B, C, and D |
If an Eagle booted from a File 10, File 40, or "File 20", 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.