Author: shelldozer

Hollywood or Dust: Episode 2 – Zarking Genius

[Repairing the PSU from an SGI Iris Indigo R3000] More Investigation In the last episode, I managed to extract one of the boards from the PSU and found it to be in superb condition. But what about the other, larger PCB? Although I could see parts of it "in-chassis", I really needed to remove it … Continue reading Hollywood or Dust: Episode 2 – Zarking Genius

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Hollywood or Dust – Episode 1: Down the Rabbit-Hole

[Repairing the PSU from an SGI Iris Indigo R3000] Oops, Retrochallenge 2017/10 has been running for a week already - better pull myself together and make an actual start on my project! Peculiarly Special The Iris Indigo has a slightly complex PSU history and situation. The original Indigo, based on the MIPS R3000 CPU, uses … Continue reading Hollywood or Dust – Episode 1: Down the Rabbit-Hole

Hollywood or Dust

As is often the case with hardware this old, my 1991 SGI IRIS Indigo R3000 will not start. Well, that's not quite completely true... Symptomania: When pressing the power-switch, the fan did not spin, neither of the two SCSI disk drives spun up, the screen remained resolutely blank, and the cute Indigo power-on tune did … Continue reading Hollywood or Dust

The Return of The Thin

I have recently acquired an old HP T5510 32/128 "thin client" device - a dedicated remote-graphical-terminal, manufactured in 2004 (not my pictures, I'll get those up in due course): With the addition of a VGA monitor, USB keyboard and mouse, and an Ethernet cable, this device can connect to remote RDP and Citrix services. Well, … Continue reading The Return of The Thin

Cherryside Addendum #1 – Others Bodges

Although Retrochallenge 04/2017 finished a few weeks ago, I have carried on with my project, making some improvements to my PS/2 keyboard interface for the 68HC11 microcontroller. Expanded-Mode Compatible In particular, I now have the hardware interface working using only PORTA (pins 3 and 7, using the pulse-accumulator for the input-clock and the bidirectional-capable pin PA3 for … Continue reading Cherryside Addendum #1 – Others Bodges

With a Cherry on the Side – Lessons Learned (Dijkstra be Damned)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller]This RetroChallenge project reached its' target - decoding, reading, and reporting PS/2 keyboard scancodes with a 68HC11 microcontroller using only internal resources (no external memory, no external I/O device controllers, no external logic, etc). I had picked a rather minimal project because I knew April would … Continue reading With a Cherry on the Side – Lessons Learned (Dijkstra be Damned)

With a Cherry On The Side – Episode Nine (Squinting Backwards)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] The Starting Situation By the previous episode, I was getting the right number of clock-pulses per PS/2 key event, but not all the scancodes received seemed correct, eg: Key Detected Scancode Expected Scancode Comment Q 0xA8 0x15 wrong W 0xB8 0x1D wrong E 0x24 … Continue reading With a Cherry On The Side – Episode Nine (Squinting Backwards)

With a Cherry On The Side – Episode Eight (Meet the Cherries)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Disaster Strikes Well, wouldn't you know it? What a day for my 17-year-old Omnibook laptop to decide that it doesn't want to work anymore! The darned thing will charge the (brand new) laptop battery happily, but refuses to recognise that it is holding any … Continue reading With a Cherry On The Side – Episode Eight (Meet the Cherries)

With a Cherry On The Side – Episode Seven (All the Way to Eleven)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Low-Level Interface Due to the slightly odd (not to mention a little inconvenient) low-level PS/2 keyboard hardware-interface, a little bit of ingenuity may be required: R1 and R2 are the pull-up resistors for the open-drain unidirectional CLK and bidirectional DATA signals. R3 and R4 … Continue reading With a Cherry On The Side – Episode Seven (All the Way to Eleven)

With a Cherry On The Side – Episode Six (the input-capture interrupt fires)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Captures but No Interrupt After the tribulations of the last few days, I decided to change the program to display the value in the IC3 captured-value register (TIC3) - the last value of the free-running 16-bit hardware cycle-counter when the most recent IC3 pin-event … Continue reading With a Cherry On The Side – Episode Six (the input-capture interrupt fires)