A computer kit from the '70s: Ithaca Audio Z80 CPU card for the S100 bus

Haven't had much time to write on my blog lately (lately being the last 5 months or so), mostly because of my job, but also because I spend most of my time doing things and saying "oh, it would be cool to blog about this once I'm done!". Then I'm done, and immediately find something else to do before I find the time to sit down and write about the last thing I did. That's how I am.

Anyway, I REALLY wanted to blog about this little project I spent a few evenings on, so here I am.
But first, a little background: do you, Reader, know about the S-100 computers? If yes, skip on, if not, I'll try to be quick and painless, leaving in-depth history and tech to specialized websites like this one.

Altair 8800 + 8" floppy disk system.
Image courtesy of Wikipedia

Building the GBA1000: Part 0x02

Ok, good news and bad news.
Bad first: I found out that the SRAM chips I got together (CY7C1049CV33-15VXC) with the GBA1000 mobo are not rated for 5v, but for 3.3v. I did not bother to check because the two got sold together as a kit... Lesson learned: ALWAYS DOUBLE CHECK THE DATASHEET!!!

Building the GBA1000: Part 0x01

Finally finished installing the 16 main RAM chips. This was probably one of the hardest SMD components to solder with a standard soldering iron (being of the SOJ type). The next hard one will be the 29F800 flash chip, which has a thin leg pitch.

Next step: make a detailed inventory of what I need and what I'm missing to continue the build...

Building the GBA1000: Part 0x00

The GBA1000 is a replacement motherboard developed by the uber amiga-expert Georg Braun for the A1000 computer by Commodore. The idea is to keep the same form factor of the original motherboard, but reworking the components and the circuit to obtain one of the most powerful ECS-based Amiga available: Motorola 68030 50Mhz processor (vs the 68000 7Mhz of the original A1000), 2Mb Chip RAM + 8Mb Fast RAM (vs 256Kb), onboard IDE (vs nothing), Zorro II expansion slot... etc etc etc.

The (almost) bare GBA1000 PCB

Exhuming an old project: Building the XT-IDE. Part 2

Between all the small packages the postman left at my door today, I got one with a few 74F573 logic ICs inside: just what my XT-IDE was missing to get basic functionality (to get the serial port working I still need the proper oscillator)!

XT-IDE being tested with a Disk-On-Module

Exhuming an old project: Building the XT-IDE. Part 1

I finally received the correct Xilinx CLPD part and the missing 74LVC1G14 for my XT-CF v1 card, so I could complete the build.

Soldering the CLPD avoiding shorts was a bit of a challenge, but a good measure of flux helped immensely. Now the board is ready to be flashed with the correct programming through JTAG. I'm waiting for a BUS PIRATE to accomplish the job.

First prototype of the AKAB (Amiga Keyboard Adapter Board)

I've finally received the printed boards for my prototype of the AKAB: the Amiga Keyboard Adapter Board I designed!
The purpose of this device is connecting a cheap & common PS/2 compatible keyboard to Amiga big-box (like the A1000, A2000 etc.) and Amiga 500 computers. The design is pretty simple, and involves a single active component (an Atmega 328P microcontroller) and a few passive ones. Everything is through-hole, so it's pretty easy to build.

Here is the first built proto:

First AKAB prototype

Exhuming an old project: Building the XT-IDE. Part 0

While cleaning up my closets (a task I make sure to accomplish at least once every ten years) I dug up two bare circuit boards from a project I undertook one or two years ago, and never completed: fitting my old XT computers with a decent and relatively new storage system.
Fitting IDE disks in such old computers can be a daunting task, if one decides to stick with then-contemporary technology the only decent solution would probably require finding an 8bit SCSI controller (with autobooting: hard!).
Lucky me, I did not want to limit myself to old tech and decided to check some homebrew options: the XT-IDE and XT-CF boards:

The two boards, both almost completed...

Both cards allow a modern IDE/CF