Vintage Computer Festival
Last updated: 19 Jun 2010 - 18:21
The UK's first vintage computer festival was held at Bletchley park over the weekend. It's an excellent venue and there were a huge number of people there. A spectacular array of vintage computer hardware was on display in addition to the contents of the National Museum of Computing and there was an excellent market for retro parts and spares, I picked up a couple of bits for my Spectrum and some manuals for the BBC Master.
Nathan's Z80 Project Mark 2: An actual Z80!!
Last updated: 06 Dec 2009 - 18:20
At long last I've fitted a Z80 into the Z80 computer. I know shocking isn't it. After months of tinkering with it and fiddling with things using the on-board PIC I finally got the boot code sorted out and the clock generation (in the new file called boot.asm). After some serious head scratching about why id didn't work, I got it all running smoothly and counting on the debug port LEDs.
New Code I've added the boot.asm file which contains the code to copy the top 8K of flash from the PIC into the system memory starting at address 0. This, along with the rest of the boot setup happens faster than you can see so it looks like the system is booting straight from ROM. The clock generation is also in the new code, I've used one of the PWM peripherals in the PIC to generate a 50% duty ratio square wave at a software selectable rate. At the moment it's hard coded into the PIC assembly code, and it's only running at 250kHz because my scope is pretty slow and I was hav
Developing an Architecture
Last updated: 08 May 2007 - 21:09
It's been a while since I thought up this project now, and it's heading for a shelf as fast as it's vestigial legs will carry it. I blame this rapid attempt at mothballing on a lack of practical progress while I'm at Uni with no Z80 chips in sight. I have however been thinking about the project a bit and come up with some basic ideas for the architecture.
Firstly, I've decided that instead of the normal idea of holding the operating system on a ROM chip that's used in most Z80 systems, I want to set it up something more like a conventional PC with a boot ROM containing the system BIOS (Basic Input-Output System) which causes the processor to boot from the IDE bus. In my design this is going to be a small compact flash card.
One advantage of this is that it should allow advanced functionality such as being able to edit a version of the operating system kernel on the device itself, reboot, test the new kernel by selecting it from a boot loader menu, if it fails, go back to the f