System 8813
ManufacturerPolyMorphic Systems
ModelSystem 8813
Released:July 1977
Price:$3,250 (1 drive) - $4,430 (3 drives)
CPU:Intel 8080A @ 1.84MHz
Memory:16K - 56K RAM
Display:64x16 text composite video, 128x48 pixels
Ports:Optional printer, cassette
Storage:Up to three internal 5-1/4 inch floppy drives
OS:"Exec": machine language, BASIC


The System 8813 is PolyMorphic's first diskette-based computer system. It was introduced in 1977, about a year after their earlier cassette-based Poly-88 computer, although for $1,450 an "upgrade kit" would convert your existing Poly-88 to the new System 8813.

The 8813 uses the same CPU card, VTI (video terminal interface), and RAM cards as the Poly-88, but in a larger chassis with ten S-100 slots instead of just five. 16K of RAM was initially included, but later systems came with 32K standard. The 8813 also includes a disk controller card to interface with the built-in minifloppy drives.

Included software is comprised of a disk operating system "Exec", an 8080 macro assembler, Disk BASIC interpreter for program development, and "WordMaster" text editor.

The 8813 consisted of a large chassis holding one, two, or three 5 1/4-inch single-sided single-density (SSSD) hard-sectored minifloppy disk drives from Shugart Associates, with each minifloppy disk holding 89,600 bytes of information. Later, a Z80-based disk controller supported double sided double-density (DSDD) to store 358,400 bytes on a single minifloppy. This more advanced controller also supported full-size external 8-inch floppy drives.

Like the Northstar Horizon computer, the PolyMorphic System 8813 is of the few computers with an actual wooden cover, and the 8813 is possibly the only consumer computer with three identical stock floppy drives. Why three? Because there is room for three, but each drive added $600 to the price of the system.

System 8813 with 1 floppy= $3,250, with 2 floppies= $3,840, with 3 floppies= $4,430, but these prices include a CRT monitor and keyboard.

Space is provided on the rear panel for mounting two optional minicards - an audio cassette interface and a serial printer interface. Each of these cards plug into the CPU card via a ribbon cable, without using up positions on the S-100 backplane.

The 8813 contains a boot ROM with a boot loader program, which allows the system to automatically boot directly from a floppy disk in drive 1 (leftmost). Additionally, a ROM based "Front Panel Mode" or "monitor" allows the user to access basic system functions. To access it, type "ENABLE" <ENTER>, then press <Ctrl><Z>. Type "G" <ENTER> to exit from "Front Panel Mode".

The popular CP/M operating system was not available for the 8813 due to memory and minidisk contraints, but in 1980 a $200 upgrade was released by PolyMorphic Systems to convert the 8813 to run CP/M software.

The beautiful wooden cabinet over the chassis is waxed, not varnished. To maintain its luster, occasionally wax it with a little high-quality furniture wax and a soft, clean cloth.


PolyMorphic Systems warned that the CPU card must always be installed in the second or third slot from the front of the card cage in order for the system to operate reliably, but in my system the CPU card must be in slot 8, otherwise the system will not even boot correctly.

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