8155 2048-Bit Static MOS RAM with I/O Ports and Timer PDIP-40
The 8155 2048-Bit Static MOS RAM with I/O Ports and Timer PDIP-40 is a multifunction peripheral device combining 256×8bits of static RAM with three programmable I/O ports (two 8-bit ports and one 6-bit port) and a 14-bit programmable binary counter/timer, designed for direct interfacing to multiplexed microprocessor buses. The device operates from a single +5VDC supply, provides a multiplexed address/data bus for economical pin usage, and is offered in standard PDIP-40 packaging to facilitate prototyping and retrofit applications.
Features
- 2048-bit static MOS RAM organized as 256×8 for program/work RAM and data buffering.
- Three programmable I/O ports (two 8-bit ports + one 6-bit port) for general-purpose digital interfacing.
- Integrated 14-bit programmable binary counter/timer with multiple operating modes for event timing and pulse generation.
- Multiplexed address/data bus with ALE support for simple microprocessor interfacing.
- Single +5VDC supply operation and TTL-compatible control signals for legacy 8-bit systems.
- Standard PDIP-40 package for breadboarding and through-hole assembly.
PINOUT
| No. | Symbol | Function |
|---|---|---|
| 1, 2, 5, 37–39 | PC0–PC5 | 6-bit I/O port or control lines. |
| 3 | TIMER IN | Timer clock input. |
| 4 | RESET | Reset input. |
| 6 | TIMER OUT | Timer counter output. |
| 7 | I/O / M | I/O or memory select input. |
| 8 | CE / CE | Chip enable input. |
| 9 | RD | Read strobe input. |
| 10 | WR | Write strobe input. |
| 11 | ALE | Address low enable input. |
| 12–19 | AD0–AD7 | Low address / data bus I/O. |
| 20 | VSS | Ground. |
| 21–28 | PA0–PA7 | 8-bit I/O port A. |
| 29–36 | PB0–PB7 | 8-bit I/O port B. |
| 40 | VCC | +5 V power supply. |
Specifications
| Parameter | Value |
|---|---|
| Memory Organization | 256×8 |
| Total Memory | 2048bits |
| I/O Ports | 2×8bit + 1×6bit |
| Timer | 14-bit programmable binary counter/timer |
| Supply Voltage | 5VDC |
| Interface | Multiplexed address/data bus with ALE |
| Logic Compatibility | TTL-level control signals |
| Access Time | ≈200–330ns |
| Package | PDIP-40 |
| Operating Temperature | −40°Cto+85°C |
Note: for full specifications, check any of the datasheets at the bottom of the page.
Applications
- External RAM and port expansion for legacy 8-bit microprocessor systems.
- I/O aggregation for control panels, data-acquisition front ends, and instrumentation.
- Timer/counter functions for event counting, PWM generation, and timed control tasks.
- Prototyping, education, and repair of vintage microcomputer and embedded systems.
Package Contents
- 1x 8155 2048-Bit Static MOS RAM with I/O Ports and Timer PDIP-40.
Documents
| Datasheet 1 | M5L8155P |
| Datasheet 2 | D8155HC-2 |
| Datasheet 3 | TMP8155P-2 |
Note: different datasheets are for different manufacturers, yet they are all compatible.
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