Looking inside a 1970s PROM chip that stores data in microscopic fuses by @kenshirriff #VintageComputing #RetroComputing #EE

Ken Shirriff posts an in-depth article about 1970s programmable read-only memory chips (PROMs).

The MMI 5300 was a memory chip from the early 1970s, storing 1024 bits in tiny fuses.1 Unlike regular RAM chips, this was a PROM (Programmable Read-Only Memory); you programmed it once by blowing fuses and then it held that data permanently. The chip I examined originally cost $70 and was built by MMI (Monolithic Memories Incorporated), a leading PROM manufacturer at the time.

The MMI 5300 and 6300 PROM chips are in ceramic packages. The chips have 1974 and 1973 date codes.

The highly magnified photo below shows the chip’s silicon die. The metal layer on top of the silicon is most visible in this photo; the transistors and resistors fabricated from silicon are underneath. The wires around the edges are the 16 bond wires between the silicon die and the external pins. In the upper left, the 1024 bits of data are stored in a 33×33 array of diodes and fuses… This chip is built from NPN transistors, unlike the MOS transistors used in most modern chips.

Die of the MMI 5300 PROM chip, holding 1024 bits of information. Click image for a larger version.

See all the details in Ken’s post here.

Ken also states on Twitter: Now, a reusable flash drive costs less with a billion times the storage.

Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 35,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/

CircuitPython – The easiest way to program microcontrollers – CircuitPython.org

Maker Business — Moving manufacturing out of China

Wearables — Take control of your LED sequins

Electronics — Current limiting!

Python for Microcontrollers — Python on Microcontrollers Newsletter: ESP32 Web Workflow for CircuitPython, CircuitPython Day 2022 and more! #CircuitPython @micropython @ThePSF @Raspberry_Pi

Adafruit IoT Monthly — Detect Radiation, ML Baby Monitor, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — JP’s Product Pick of the Week 8/10/22 Motorized Slide Potentiometer @adafruit @johnedgarpark #adafruit #newproductpick

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !

No Comments

No comments yet.

Sorry, the comment form is closed at this time.