Brachman Associates Serial Box Print Buffer for VIC-20

I don't know too much about this company. R. J. Brachman Associates, Inc. (RJB) of Havertown, Pennsylvania provided consulting services in the field of warfare concepts - namely: weapons, fire control and support concepts. MICROSPORT provided computer controlled electronic units for use in connection with sporting and athletic events - namely: signal generators, timers, and display generators. This included a MMC/02A Microsport CMOS microcomputer used in a blood pressure monitoring device, as well as single-board computer kits leveraging the CSG/MOS 6500 microprocessor family.

This Serial Box 64K Buffer is a transparent print buffer for the IEC bus. This device buffers data in RAM and then spools the data to the printer as it will accept it, allowing the computer to be freed more quickly. (By default a Commodore VIC-20 will be tied up until the printer has accepted all of the data for printing on the IEC bus.) LEDs on the top of the unit alert when it is running, paused, or when the 64K buffer is full. A brief push and a button would pause the printing or reset the unit.

This device connects inline between the computer and IEC printer using permanently cabled male and female 6-pin DIN connectors. It derives its power from the computer’s cassette port or user port (+5v DC), like many printer interfaces. The Serial Box uses a 65C02 microprocessor with a 2732 EPROM for its firmware. The manual identifies it as version 6.06. Eight 64Kx1 DRAMs hold the buffer. It contains no I/O device such as a 6522 VIA, and instead uses only 74xx series devices to control the IEC ports.

You can right-click and download the manual here. It was not available anywhere else online before now, so it has also been sent to http://www.bombjack.org/commodore for safe keeping.