Callan Multibus 68k CPU board - Introduction

• Original Callan brochure (PDF, 2 pages)

As an aside from the brochure, they say that the machine can accomodate up to 4 additional users! It just goes to show what people expected from machines back then as compared to what they expect these days. (It also shows the imagination of marketing people).

Callan used this board along with their own floppy, "winchester" and other controller boards to put together a desktop computer. The date codes on the chips are 1982, making this a 40 year old piece of computing hardware. Maybe this is my entry into "retro-computing"

As an interesting comparison, the first IBM PC was introduced in August of 1981 with a 4.77 Mhz 8088 processor (8/16 bit). It had floppy disks. This board, introduced at more or less the same time had an 8.0 Mhz 68000 that was 16/32 bit. It had a 21M hard drive.
At the time it was an impressive piece of hardware to have in your office.

The board now has a 64 pin MC68000L10 processor. The crystal is 16 Mhz, so it is going to run at 8 Mhz.

The board has 256M of dram (using an array of 64k by 1 bit chips),] with parity. It even has an MMU implemented with static ram and some TTL logic. At one time it ran Unix edition 7.

Other than TTL, the only other large chips on the board are a NEC 7201 dual channel UART and an AMD 9513 timer chip.

The NEC 7201 is identical to the Intel 8274.

There are 4 rom sockets (28 pin) U101 to U104. More about these on another page.