Kimtron ABM 85

Kimtron ABM 85
Manufacturer	Kimtron
Model	ABM 85
Lifetime
Introduced	May, 1982
Introductory Price	$995
Communication
Interface	RS-232C
Baud Rates	75, 110, 150, 300, 600, 1200, 2400, 4800, 9600 19200
Display
Phosphor	P31
Character Modes
Resolution	80x24
Status Line	Yes

The Kimtron ABM 85 terminal was introduced in May, 1982 at a price of $995. In March, 1983 the ABM 85H was introduced as an improvement.^[1]^[2]^[3] ^[4]

Hardware

Logic Board

The Kimtron ABM 85, as the name suggests, used the 8085 microprocessor.

For video, it used the Intel 8275 and accompanying font ROM (2716), notably the system does not include a DMA controller often paired with the 8275.

RAM consists of up to ten Intel 2114 static RAM chips for a total of 5k, basic configurations only consisted of six RAM chips for a total of 3k.

ROM consists of two 2732 (4k) chips and a third unpopulated socket.

Three Intel 8251 UART chips provide communication with the keyboard, main serial port and auxiliary serial port. The line drivers and line receivers used are the TI MC1489 and MC1489.

Power Supply

The Kimtron ABM 85 has a very simple linear power supply. It provides the system with +5v, +12v and -12v. The power supply provides no protection other than what the linear regulators may have built-in.

Observed Hardware Failures

The 8275 CRT controller chips appear to be prone to failure.
Ageing capacitors in one system have failed damaging the vertical deflection circuitry

Firmware

Two versions of the firmware are known to exist.

SP15-00 & SP15-01
SP13-00 & SP13-01

The only observed difference is that SP15 will show a test pattern on the screen in case of a memory error. While SP13 will just show a cursor in the upper left corner.