GSAS 85A Microprocessor Trainer

The GSAS 8085 Trainer Kit is the foundation-level microprocessor training platform used across Indian engineering colleges for introductory courses in microprocessor architecture and assembly language programming. Built around the Intel 8085A processor, this trainer provides a complete standalone learning environment with a hex keypad for program entry, LED/7-segment display for output, built-in monitor ROM for program execution and debugging, and an expansion bus interface for connecting GSAS Peripheral IC Study Cards.

The built-in monitor program stored in EPROM provides essential development functions, memory examine and modify, register display, single-step execution, breakpoint setting, and program run/halt control, all operated through the hex keypad without requiring a PC connection. This self-contained approach teaches students the fundamentals of machine code entry, memory organisation, and manual debugging, building a deep understanding of how processors execute instructions at the hardware level. For more advanced usage, the trainer supports USB and RS232 (optional) serial communication with a PC for cross-assembler workflows. On-board peripheral ICs include the 8253, 8251, 8259, 8255, and 8279, and the board features a parallel printer port with active high/active low stepper motor interface and DC motor control.

The expansion bus connector is a key feature that extends the trainer’s capability by accepting GSAS Peripheral IC Study Cards (8251/8253, 8255, 8259, 8279). Each study card plugs directly into the trainer bus and provides a dedicated interfacing platform for one peripheral IC, allowing students to progressively learn peripheral programming as the course advances. With 32 KB of RAM and 16 KB of EPROM, the trainer provides ample memory for student programs and monitor firmware.

System Specifications

Parameter	Value
Processor	Intel 8085A, 3/5 MHz
RAM	32 KB (expandable)
EPROM	16 KB with monitor program
Keypad	24-key hex keypad
Display	6-digit 7-segment LED
Serial	USB, RS232 (Optional)
Expansion Bus	50-pin bus for peripheral study cards
Power Supply	Requires external power supply (Supply rails: +5V @ 3A, +12V @ 250mA, -12V @ 250mA, +30V @ 100mA)
Onboard Peripherals	8253, 8251, 8259, 8255, 8279
Parallel Printer Port	Active high, active low stepper motor interface, DC motor

Lab Experiment Coverage

Experiment Category	Topics
Data Transfer	MOV, MVI, LDA, STA, LDAX, STAX operations
Arithmetic	8/16-bit addition, subtraction, multiplication, division
Logical Operations	AND, OR, XOR, complement, rotate, compare
Branching	Conditional/unconditional jumps, subroutines, CALL/RET
Stack Operations	PUSH, POP, stack pointer manipulation
Interrupts	RST, TRAP, hardware interrupt handling
Peripheral Interfacing	Via expansion study cards (8255, 8253, 8259, 8279)
Serial Communication	UART programming, PC data exchange

Why GSAS

GSAS has manufactured the 8085 Trainer Kit for decades, making it one of the longest-running and most widely deployed microprocessor training platforms in Indian engineering education. The trainer’s expansion bus interface creates a modular learning path, start with the base trainer for 8085 fundamentals, then add Peripheral IC Study Cards as the course progresses through interfacing topics. Colleges benefit from volume pricing for complete lab setups (trainer plus study card sets), structured lab manuals, and direct support from the GSAS education products team.

Products are available for immediate purchase through the GSAS online store (“Buy on Store”) or through direct engagement for institutional and volume orders (“Request Volume Pricing”).