OIS Peripherals

Many peripheral devices were produced to connect to OIS systems, including printers, workstations, telecommunications/network controllers, and a ton of obscure things like cash registers and EPROM programmers. All peripherals, except disk drives, are connected to the OIS Master processor through a serial data link called a '928' It is a 4.5Mb/Sec. interface implemented in a dual-coaxial cable connection. Each side of the dual-coaxial cable is one half of a differential data link - one +5v and one -5v. It is a sync interface, the Master sends a command to a slave device, and the slave responds. Slaves cannot initiate commands and drive the interface directly. One slave device is connected to each port on the Master.

Many OIS peripherals ('Slaves') do not have any firmware or PROMS in them at all. For the ones that do have firmware, it is used for diagnostics only. OIS slaves are 'dumb' and don't know how to do anything until loaded with a program from the Master.

Workstations

There were many workstations made for the OIS. Some of them are identical to VS workstations. These are workstations that I have or have had at one time:

5536	One-piece workstation. Similar to the VS 2256.
4230	Three-piece workstation.
AWS	Archiver. 5536-like terminal connected to box with 8" floppy drive.
Wang PC	Sort-of IBM-PC compatible computer. Can have a coaxial interface installed into it.

Some add-on cards were available for workstations. I have a RS-232 serial interface card, it uses the Intel 8251 chip and has a maximum speed of 9600 baud. It is used in the 5536 workstations.

Printers

Many printers were available for the OIS. Some were standard printers with a coaxial interface card adapted to them. I do not have any OIS printers, so I cannot catalog them here. I do have a LDP8-SYS, which allowed you to hook a HP LaserJet printer to the OIS. It is a 64k Z80 board with the coaxial interface and a standard parallel port. Unfortunately, I have no software for it, so I will have to write my own.

Other Peripherals

There are several telecommunications controllers for the OIS. The earliest ones used Intel 8080 microprocessors and 8251 UARTs. These were housed in a 'black box' that was about 12" wide, 10" tall, and 16" long. They were heavy and had a transformer in them (linear PS). These were connected to OCR equipment too. The newer ones are contained on an OIS-140 style board, and are Z80-based with the Z80 SIO. These are capable of higher speeds than the 'black box' interface. These boards are still used on VS systems.

Data Link commands

There are few commands you can send to a Slave through the Data Link:

Status	Obtain device status
Restart	Resets CPU in slave to location 'x0000'
1Read	Read one byte from slave memory
1Write	Write one byte to slave memory
256Read	Read 256 bytes (one page) from slave memory
256Write	Write 256 bytes (one page) to slave memory

So, to 'cold-start' a slave, one could do the following:

Write three bytes starting at x'0000' - x'c3' x'00' x'00' (jp 0000)
Send Restart command
Write program data to the slave device
Change the data at x'0000' and restart the slave again (jp instruction to start of program)

You set aside memory in the slave to communicate with the master. It polls this area for requests, reads/writes data, and posts the results in this area.

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