CADO Computer Corporation

CADO Computer Corporation

CADO Systems was one of the first manufacturors of (Intel) microcomputer based business system with disk drives, application software, a compiler for the proprietary (BASIC-like) interpreted language "CADOL". The first prototype used an 8008 and sprang to life in 1973. By 1975 CADO was shipping priduction systems.

The first systems built were the 8085 "/1" systems with 4K of main memory and an 8 inch floppy drive. They could handle 1 serial port connected to one CRT based termial with keyboard - one user.

By the late seventies these had grown into the /4 systems with 16, 32 and later 48K of memory. These multitasked by using a hardware tick to XOR the base address of where the native ("CADOL" a basic like-) interpreter took instructions from. These also used 8085 processors. The memory switching trick was done with proprietary hardware. The "/4" system had 4 serial ports, therefore 4 terminals, therefore 4 users. The could also be connected to modems instead and spoke various protocols such as X.25.

The /8 was two /4's sharing a common (hard) disk drive. It was effectivly an 8 user system built out of two 8085s.

Around the time of the /8 development the CADO CAT computer came into being. It looked like a fruit flavoured iMac, but it was 20 years earlier. It had an integrated CRT and disk drives, which by this time (1981) had been shrunk to a mere 5" wide and could fit inside the CRT enclosure. Earlier CADO computers used external hard drive, all of which were quite large.

The CAT product line consisted of:


The CAT III was a three-user system. The primary user sat at the CAT III system console, which contained the CPU, floppy drive, and hard disk. Other users connected to the system by way of serial terminals. By the end of the CAT series over 25,000 systems and 200,000 terminals were manufactured. If the CAT had had a bitmapped display it would have seemed like the first Apple macintosh without the Xerox GUI.

The terminals were proprietary also: they were similar to standard [[VT100|VT terminals]], but with custom firmware programming to support input commands (protected fields).

All CADO systems up to this point had the system and CADOL interpreter reside in EPROM, so as soon as power was applied it read track 0 sector 0 of the diskette and began executing CADOL code. The IL codes for the interpreter written by Jim Ferguson looked similar to Tannenbaums optimized IL codes from his empirical study. The laguage was extended by Richard Sexton who added Pascal/C like syntax and 65K instead of 256 byte program overlay sizes. Previous to this CADOL worked in programs no longer than 256 bytes of IL code long and when the programmer had code that hit about the 200 byte mark they would have to issue a LOAD statement to load the next 256 bytes of CADOL IL codes. At some point when a fair number of applications had been written the loading of overlays was made transparent by Sexton's modifications to the interpreter up to an apparant program of 65K. Dan Lanham rewrote the compiler. This was all done in Intel 8085 assembly.

After the /8, The technical staff wanted to gang more of these machines together, but the marketing department demanded 16-bit systems. The Motorola 68000 was the preferred choice of software people, but Bob Thorne, VP of hardware delivered the bad news Motorola only had a great cpu while intel had a cpu and chipset family of CTCs, interrupt controllers, serial ports, DMA controllers and x86 became the rule much to the shock and horror of the software staff who thought Bob should just build all those bits he didn't have. But Bob was instead working on two disk controllers as these were not off the shelf chips quite yet. One design, not used was based on 8x300 bitslice parts but it never saw the light of day.

The 16-bit 8086 tiger systems began development in intel development sytems as there were no working commercial 8086 based computers at the time.

The Tiger was radically different. All previous CADO computers had been single board systems that would probably be familiar to anybody who has ever seen a modern motherboard, the parts were just bigger, and there were less of them.

But the Tiger looked more like a DEC computer - it had a (Multibus) backplane that would hold up to 10 plug in cards into this mainframe, and was one of if not the first multi-microprocessor based mainframe systems.

There were three plug in cards, the "terminal" card had an 8086 chip and 16 serial ports, the "cpu" card had the (8086) cpu that ran CADOL III and an optional disk processor used an 8089. You had to have one cpu card, one terminal card although you could have many of these in increments of 16 serial ports, later also in increments of 8 ports.

With the 8086 came the net and around 1984 or 1986 CADO connected to the UUCP based Usenet news and mail networks and finally had a unix system, requisitioned to run mail and news which engineering considered vital while the rest of the company had no idea what it was.

Before the first Tiger was sold though, George Ryan, the founder of the company left and the IBM PC came out. And this was in many ways the end of CADO. At one time one of the fastest growing companies in California, CADO was now sold to/merged with Contel.

rjs - 28-nov-08