Wednesday, March 31, 2010

HFE: Sacramento Area Electronics Parts Source

There's a neat little place in Sacramento--next door to North Highlands--that sells lots of electronics supplies and surplus stuff, as well as some consignments. It's called HFE Electronics. It's at the prior location of HSC (Halted Specialties Corp., better known as HSC Electronic Supply.) HSC decided to consolidate, pulling out of the Sacramento location after over 25 years and focusing their attention on their Bay Area store and online sales.


HFE fills the gap that would have been left with the loss of HSC in this area. Not only that, but they've picked up for the Popkey Electronics store that recently closed here. They bought out Popkey's stock and are integrating it into their inventory now.

HFE is a fun place to poke around, ask questions of the staff (or, in my case, I more often get involved in helping the staff answer questions from other customers) and otherwise pick up all sorts of fun bits of electronics. They have everything from discrete components to ICs to equipment. There's new retail stuff as well as heaps of surplus and used stuff. There's lots of bits and bobs for those of us who like playing with microcontrollers, those of us who like building up analog circuits from scratch, amateur radio people, digital electronics types, tinkerers with pre-existing equipment, repairers of the $100 item with a broken ten cent part, and so on. Count me in all the above categories. I seldom get out the door without being about $100 lighter. :)

Among the things I noticed my last time in (no guarantees this will all be there when you walk in, especially if I beat you there) are:
  • An Odyssey 2 game console from the 70s (based on the 8048 CPU, with lots of room inside the case for mods!

  • Some Tek scopes and modules

  • An old Mac SE/30 unit (sans keyboard and mouse.)

  • Lots of interesting rocker switches

  • A bunch of LCD displays with 44780 controllers and similar

  • Oodles of LEDs and displays (I've picked up a bunch of dual digit 14 segment displays, among others.)

  • Prototyping boards, tools, wire jumpers for solderless breadboards, and other proto stuff.

  • Interconnects and sockets of all sorts of varieties.

This barely scratches the surface, and while some things are one-offs (like the Mac and Odyssey 2), much else is regular stock stuff. So if you're ticked about the fact that "Chicken Shack" doesn't have your favorite digital latch any more, take a stop by HFE Electronics.

Monday, March 29, 2010

8085 Project Schematic Posted

I've posted a schematic for my 8085 based single board computer, the MAG-85, on my web site. The schematic covers the entire main board, previously I had only posted schematics of parts of the system in the assembly instructions.

Click the image to go there. The schematic is linked under "References" at the bottom of the page.



I'm presently completing the parts of the schematic that cover the front panel components as well as the bill of materials. This will all be posted as a PDF once it is complete.

In hardware, I have finished the keyboard and am assembling the front panel and the enclosure. This is all turning out very nicely, I'll be posting pictures soon. I'm especially happy with how the keyboard turned out. It looks really spiffy, even though it was created using very low-tech methods (I'm working to keep the whole project at a garage and desktop tech level for construction.)

Thursday, March 18, 2010

8085 Microprocessor Project: MAG-85

Here's a picture of the completed hand-wired circuit board for the MAG-85 (Micro Applications Gadget) 8085-based microcomputer system:
MAG-85, 8085 CPU computer with 8K RAM, 4x5 matrix keypad, LCD display,and 16 additional digital I/Os.

More info on this project at saundby.com.

I'm presently working on both a permanent front panel/enclosure and the permanent software. I'll be writing a machine language monitor program that will provide a number of utility routines for using the system's I/O.

The system has a 4x5 keypad,and an LCD display (16x2 is used here, I'll write the software to allow any two-line display from 16x2 to 40x2.) It also has 16 extra digital inputs and outputs. In the image eight of each are in use to read the state of a bank of DIP switches and display that on the 8 LEDs. The system can be expanded off-board with up to an additional 40 additional I/Os with the present I/O decoders.

The 8085's interrupt inputs are available as well, above I have switches on TRAP (the 8085's non-maskable interrupt) and RST7.5. RST6.5 is used by the keyboard, and RST5.5 will also be available on the front panel as a user program vector switch.

Everything's coming together nicely on this project now. I have detailed instructions on constructing the circuit on the project web page, with detailed instructions for a hand-wired board like the one above soon to come.

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